20201350326Effect of Guide Vane Pitch Circle Diameter on Pressure Fluctuation in Vaneless Zone of Francis Turbine22In a Francis turbine, the guide vanes are arranged in the direction of flow behind the stay vanes. And as it is generally believed that the outlet angle of water after it flows through the spiral case and stay vanes is fixed, the flow and flow circulation are altered by changing the opening of the guide vanes so as to change the output of the turbine. The rotor–stator interaction effect induced by the interaction between the guide vanes and the runner of the Francis turbine was one of the main causes of the pressure fluctuation. The effect of guide vanes placement on pressure fluctuation in vaneless zone of Francis turbine was studied. In this study, the commercial software ANSYS CFX16.0 was used for the three-dimensional numerical simulation of the whole flow passage of a Francis turbine model in a power station. The turbulence model used in the calculation was the shear stress transport (SST) model. The independence between the total number of computational meshes and the timestep was verified to ensure the reliability of the calculation results. Five schemes with different diameters of the guide vanes distribution circle were proposed including D0/D1 (guide vane pitch circle diameter /diameter of runner inlet) equaling to 1.119, 1.128, 1.138, 1.144, and 1.15. The steady calculation results showed that, when the turbine was operating under the design condition, D0/D1 increased from 1.119 to 1.15, and the turbine efficiency and output showed a monotonically increasing trend, with the efficiency increased by 0.17 percentage point and output increased by 3.91kw. Twenty monitoring points were set up in the vaneless zone between the guide vanes and the runner to collect pressure fluctuation signals in the vaneless zone. By analyzing the characteristics of unsteady pressure fluctuations in the vaneless zone under design conditions of the five schemes, the optimal position of the guide vanes was determined. The numerical results showed that the pressure fluctuation amplitude at monitoring points in the same axial direction increased gradually from the top cover to the bottom ring. When the unit operated under the design conditions, by increasing the guide vane pitch circle diameter, the rotor–stator interaction between the guide vanes and the runner domain was weakened, and the pressure fluctuation amplitude in the vaneless zone between the guide vanes and the runner was reduced, thereby the stability of unit operation was improved. 13491369Z. J. WuInstitute of Water Resources and Hydro-electric Engineering, Xi’an University of Technology, Xi 'an 710048, ChinaInstitute of Water Resources and Hydro-electric Engineering, Xi’an University of Technology, Xi 'an 710048, Chinapayswuzijuan.xa@qq.comW. K. LiangInstitute of Water Resources and Hydro-electric Engineering, Xi’an University of Technology, Xi 'an 710048, ChinaInstitute of Water Resources and Hydro-electric Engineering, Xi’an University of Technology, Xi 'an 710048, Chinapaysliangwuke@vip.163.comW.DongCollege of Water Resources and Architectural Engineering, Northwest A&F University, Yangling, Shaanxi 712100, ChinaCollege of Water Resources and Architectural Engineering, Northwest A&F University, Yangling, Shaanxi 712100, Chinapaysdongw@nwafu.edu.cnFrancis turbine Guide vane Pitch circle diameter Vaneless zone Pressure fluctuation.[Anup, K. C., B. Thapa and Y. H. Lee (2014). Transient numerical analysis of rotor-stator interaction in a Francis turbine. Renewable Energy 65, 227-235.##
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]Numerical Study on the Anti-Snow Performance of Deflectors on a High-Speed Train Bogie Frame22In this paper, a new installation of flat plate deflector which attached on the bottom of the bogie frame is proposed and its anti-snow accumulation performance with different attack angles is numerically studied. The wind-snow two-phase flow in the bogie region is simulated based on the Reynolds Averaged Navier-Stokes (RANS) equations combined with the Realizable "k-ε" turbulence model and the Lagrangian particle phase method. The adopted numerical simulation methodology is verified and validated by comparing with previous wind tunnel tests. In this paper, three typical attack angles (30°, 60°, 90°) for deflector are studied. The results show that: the 30° case has a medium influence on the flow field and reduces snow accumulation by 35.14%; the 60° case guides the high-speed airflow downward and has the best effect with 62.46% reduction in snow accumulation; the 90° case has the smallest reduction with 20.30% in the mass. Overall, all deflectors with three different installation angles can reduce the mass of snow accumulated on the bogie surface.13771389G.GaoKey Laboratory of Traffic Safety on Track of Ministry of Education, School of Traffic & Transportation Engineering, Central South University, Changsha, Hunan, 410075, ChinaKey Laboratory of Traffic Safety on Track of Ministry of Education, School of Traffic & Transportation Engineering, Central South University, Changsha, Hunan, 410075, Chinapaysgjgao@csu.edu.cnQ.ChenKey Laboratory of Traffic Safety on Track of Ministry of Education, School of Traffic & Transportation Engineering, Central South University, Changsha, Hunan, 410075, ChinaKey Laboratory of Traffic Safety on Track of Ministry of Education, School of Traffic & Transportation Engineering, Central South University, Changsha, Hunan, 410075, Chinapays1256468831@qq.comJ.ZhangKey Laboratory of Traffic Safety on Track of Ministry of Education, School of Traffic & Transportation Engineering, Central South University, Changsha, Hunan, 410075, ChinaKey Laboratory of Traffic Safety on Track of Ministry of Education, School of Traffic & Transportation Engineering, Central South University, Changsha, Hunan, 410075, Chinapaysjie_csu@csu.edu.cnY.ZhangKey Laboratory of Traffic Safety on Track of Ministry of Education, School of Traffic & Transportation Engineering, Central South University, Changsha, Hunan, 410075, ChinaKey Laboratory of Traffic Safety on Track of Ministry of Education, School of Traffic & Transportation Engineering, Central South University, Changsha, Hunan, 410075, Chinapays1062426943@qq.comZ.TianKey Laboratory of Traffic Safety on Track of Ministry of Education, School of Traffic & Transportation Engineering, Central South University, Changsha, Hunan, 410075, ChinaKey Laboratory of Traffic Safety on Track of Ministry of Education, School of Traffic & Transportation Engineering, Central South University, Changsha, Hunan, 410075, Chinapays1114012873@qq.comC.JiangKey Laboratory of Traffic Safety on Track of Ministry of Education, School of Traffic & Transportation Engineering, Central South University, Changsha, Hunan, 410075, ChinaKey Laboratory of Traffic Safety on Track of Ministry of Education, School of Traffic & Transportation Engineering, Central South University, Changsha, Hunan, 410075, Chinapaysjiangchen2007@hotmail.comSnow accumulation Lagrangian particle phase Wind-snow two-phase flow High-speed train bogie.[Bettez, M. (2011). Winter technologies for high speed rail. Norwegian University of Science and Technology, Trondheim, Norway.##
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]Sloshing Analysis of a Heterogeneous Viscous Liquid in Immovable Tank under Pitching Excitation22The effects of the heterogeneity of liquid on the tank sloshing under pitching excitation are analyzed and discussed. The time history of the free surface elevation for tank containing a homogeneous – heterogeneous liquid are recorded and discussed. Numerical simulations are performed for various functions of density using the finite-element method. A theoretical model in the case of heterogeneous viscous liquid are developed using the variation formulation based on the Navier-Stokes equations. The effect of viscosity on the responses is also discussed for each case. In each case, the time history plots for the vertical fluid displacement at a select node, and the pressure in selected elements are presented to illustrate the results of numerical simulations. The effect of heterogeneity parameter of the amplitude of liquid sloshing in a two dimensional partially filled rectangular tank under pitch excitation is conducted to investigate the effects of excitation variable density on the liquid sloshing by a series of numerical experiments. The results are compared with existing theoretical study and the comparison shows fair agreement.13911405J.El BahaouiAbdelmalek Essadi University, Faculty of sciences, Department of Physics, Laboratory M2SM, Tetuan, MoroccoAbdelmalek Essadi University, Faculty of sciences, Department of Physics, Laboratory M2SM, Tetuan, Moroccopaysjelbahaoui@yahoo.comH.EssaouiniAbdelmalek Essadi University, Faculty of sciences, Department of Physics, Laboratory M2SM, Tetuan, MoroccoAbdelmalek Essadi University, Faculty of sciences, Department of Physics, Laboratory M2SM, Tetuan, Moroccopaysjalalpc2@yahoo.frL.El BakkaliAbdelmalek Essadi University, Faculty of sciences, Department of Physics, Laboratory M2SM, Tetuan, MoroccoAbdelmalek Essadi University, Faculty of sciences, Department of Physics, Laboratory M2SM, Tetuan, Moroccopaysjalal_190@hotmail.comHeterogeneous and viscous Liquid Numerical simulation Variational method Sloshing analysis Pitching excitation.[Akyildiz, H. (2012), A numerical study of the effects of the vertical baffle on liquid sloshing in two-dimensional rectangular tank. Journal of Sound and Vibration 331, 41–52##
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]Numerical Investigation of the Effects of Leakage Flow From Guide Vanes of Francis Turbines using Alternative Clearance Gap Method22Flow around the Guide vanes (GV) in Francis turbine differs with the shape of hydrofoils. The difference in the pressure of fluid travelling to pressure side and suction side of GV contributes to flow behavior. This study presents the numerical technique using alternative clearance gap method to predict the flow around GV and its consequent effect on turbine performance. GV profile has a significant effect on the performance of the turbine with sediment contained fluid flow. In this paper, symmetrical NACA 0012 and cambered NACA 2412, NACA 4412 hydrofoils are studied introducing 0 mm, 2 mm, and 4 mm clearance gaps. Vortex filament can be seen when fluid leaves the clearance gap due to the leakage flow occurring through the gap. The intensity of vortex leaving clearance gap rises with an increase in the size of the clearance gap. However, in the case of asymmetrical GV profile, the velocity of fluid travelling along the vortex compared to that of symmetrical hydrofoil is lower. In case of low specific speed Francis turbines, this vortex is found to be a major reason to erode the runner surface due to high velocity of a sand particle travelling with them. With the alternative clearance gap approach, this paper compares the pressure pulsation downstream of GVs contributed by leakage flow for three NACA profiles, whose frequency is half of blade passing frequency. 14071419S.GautamTurbine Testing Lab, Kathmandu University, Dhulikhel, 45210, NepalTurbine Testing Lab, Kathmandu University, Dhulikhel, 45210, Nepalpayssaroj.gautam2019@hotmail.comH. P.NeopaneTurbine Testing Lab, Kathmandu University, Dhulikhel, 45210, NepalTurbine Testing Lab, Kathmandu University, Dhulikhel, 45210, Nepalpayshari@ku.edu.npB. S.ThapaTurbine Testing Lab, Kathmandu University, Dhulikhel, 45210, NepalTurbine Testing Lab, Kathmandu University, Dhulikhel, 45210, Nepalpaysbst@ku.edu.npS.ChitrakarTurbine Testing Lab, Kathmandu University, Dhulikhel, 45210, NepalTurbine Testing Lab, Kathmandu University, Dhulikhel, 45210, Nepalpayssailesh@ku.edu.npB.ZhuDepartment of Energy and Power Engineering, Tsinghua University, Beijing, 10084, ChinaDepartment of Energy and Power Engineering, Tsinghua University, Beijing, 10084, Chinapaysbszhu@mail.tsinghua.edu.cnFrancis turbine Sediment erosion Leakage flow Vortex Efficiency RSI Blade passing frequency.[Acharya, N., C. Trivedi, N. M. Wahl, S. Gautam, S. Chitrakar and O. G. Dahlhaug (2019). “Numerical study of sediment erosion in guide vanes of a high head Francis turbine”, IOP Conf. Series: Journal of Physics: Conf. Series, No. 1266:12004.##
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]Kelvin Waves Structure Analysis of a Horizontal Axis Wind Turbine Tip Vortices22The optimization of the wind energy conversion is one of the most important domains which was widely interested researchers. The instabilities in the wind turbine wake are one of the sources of energy loss which strongly influenced the helical tube vortex structure and are generally difficult to be quantified using experimental facilities. This paper presents a numerical investigation on the wake downstream of a horizontal axis wind turbine (HAWT) model using the Fluent software. Results were validated using experimental measurements conducted in the CRTEn wind tunnel. The Kelvin wave’s theory was, also, used to analyze the deformations acting on the tip vortices. The cartography of the velocity gradient tensor components of the first tip vortex and the different families of Kelvin wave’s were studied and classified according to the azimuth wavenumber. The obtained results confirm that the tip vortices meandering correspond to the helical mode of Kelvin wave’s and the stretching-compression phenomenon is the most important deformation acting on the tip vortex tubes during the development of HAWT wake.14211435M. M.OueslatiLaboratory of Wind Energy Management and Waste Energy Recovery, Research and Technologies Center of Energy, Ecoparck of Borj-Cedria, BP 95 Hammam lif, 2050, TunisiaLaboratory of Wind Energy Management and Waste Energy Recovery, Research and Technologies Center of Energy, Ecoparck of Borj-Cedria, BP 95 Hammam lif, 2050, Tunisiapaysmehdi.oueslati@crten.rnrt.tnA. W.DahmouniLaboratory of Wind Energy Management and Waste Energy Recovery, Research and Technologies Center of Energy, Ecoparck of Borj-Cedria, BP 95 Hammam lif, 2050, TunisiaLaboratory of Wind Energy Management and Waste Energy Recovery, Research and Technologies Center of Energy, Ecoparck of Borj-Cedria, BP 95 Hammam lif, 2050, Tunisiapaysdahmouni_anouar_wajdi@yahoo.frS.Ben NasrallahLaboratory of Thermal and Energy Systems Studies National Engineering School of Monastir, Street Ibn El Jazzar, Monastir, 5000, TunisiaLaboratory of Thermal and Energy Systems Studies National Engineering School of Monastir, Street Ibn El Jazzar, Monastir, 5000, Tunisiapayssassi.bennasrallah@yahoo.frHorizontal axis wind turbine Three-dimensional wake Kelvin waves velocity gradient tensor Flow separation Stretching-compression. [AbdelSalam, A. M. and V. Ramalingam (2014). Wake prediction of horizontal-axis wind turbine using full-rotor modeling. Journal of Wind Engineering and Industrial Aerodynamics 124, 7-19.##
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]Design of Crescent Splitting Electrodes in EWOD Device22High control voltage and low success rate limit the application of droplet cutting on digital microfluidic chip, hence, the traditional square electrode was designed to crescent electrode to solve these problems in this paper. First, the relationship between the EWOD tension of micro-droplet and the chord length of effective Triple Contact Line (TCL) was analyzed based on the theory of electrowetting-on-dielectric. Then, the droplet cutting processes of different electrodes were numerically simulated and the results were analyzed. Finally, the effect of droplet cutting on four kinds of chips were tested. The results revel that the crescent electrode can decrease the applied voltage for droplet cutting and the minimum voltage required for cutting on crescent electrode (A=1.41) was at least 13.9% lower than that of square electrode. In addition, the success rates of droplet cutting on crescent electrode at different channel heights are higher than that of square electrode. 14371442Z.WangRobotics & Microsystem Center & Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University Suzhou 215123, ChinaRobotics & Microsystem Center & Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University Suzhou 215123, Chinapayszlwang23@stu.suda.edu.cnL.ChenRobotics & Microsystem Center & Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University Suzhou 215123, ChinaRobotics & Microsystem Center & Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University Suzhou 215123, Chinapays1749611351@qq.comX.BianRobotics & Microsystem Center & Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University Suzhou 215123, ChinaRobotics & Microsystem Center & Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University Suzhou 215123, Chinapays349323895@qq.comElectrowetting-on-dielectric Digital microfluidics Crescent electrode Splitting voltage.[Choi, K., A. H. C. Ng, R. Fobel and A. R. Wheeler (2012). Digital microfluidics. Annual Review of Analytical Chemistry 5, 413-440.##
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]Numerical Simulation of Aerodynamics of Train with Broken Windows22Window glass of the train was broken several times when running in the strong wind/sandy areas, causing safety risks to passengers and serious problems to the operation of the train. The aerodynamic performances of the train with broken windows in strong wind condition are uncertain. These problems remain the challenging research issues. To study these issues, the influence of the broken windows on the aerodynamic performances of the train model was analyzed using three-dimensional numerical simulation methods. The results showed that the aerodynamic forces on the second passenger car first decreased and then increased within a very short period when the two middle windows on the windward side had been broken. However, the side force and the overturning moment increased sharply when the wind angle was increasing. In addition, the number of broken window glass has significant effects on train aerodynamics when running in cross wind area, and the absolute value of the side force and of the overturning moment increased significantly with the increase in the number of broken windows on windward side.14431452J.DuKey Laboratory of Traffic Safety on Track of Ministry of Education, Central South University, Changsha, Hunan 410075, ChinaKey Laboratory of Traffic Safety on Track of Ministry of Education, Central South University, Changsha, Hunan 410075, Chinapaysenglishtvcom@126.comM.YangKey Laboratory of Traffic Safety on Track of Ministry of Education, Central South University, Changsha, Hunan 410075, ChinaKey Laboratory of Traffic Safety on Track of Ministry of Education, Central South University, Changsha, Hunan 410075, Chinapaysgszxymz@126.comL.ZhangKey Laboratory of Traffic Safety on Track of Ministry of Education, Central South University, Changsha, Hunan 410075, ChinaKey Laboratory of Traffic Safety on Track of Ministry of Education, Central South University, Changsha, Hunan 410075, Chinapaysgszxzhanglei@126.comF.WuKey Laboratory of Traffic Safety on Track of Ministry of Education, Central South University, Changsha, Hunan 410075, ChinaKey Laboratory of Traffic Safety on Track of Ministry of Education, Central South University, Changsha, Hunan 410075, Chinapaysgszxcfd_wf@csu.edu.cnW.HuangKey Laboratory of Traffic Safety on Track of Ministry of Education, Central South University, Changsha, Hunan 410075, ChinaKey Laboratory of Traffic Safety on Track of Ministry of Education, Central South University, Changsha, Hunan 410075, Chinapaysgszx@126.comNumerical simulation Train window glass Strong wind Side force Overturning moment.[Baker, C. J. (1986). Train aerodynamic forces and moments from moving model experiments. Journal of Wind Engineering and Industrial Aerodynamics 24, 227–251.##
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]An OpenFOAM-Based Evaluation of PANS Methodology in Conjunction with Non-Linear Eddy Viscosity: Flow Past a Heated Cylinder22We evaluate the partially-averaged Navier-Stokes (PANS) methodology of turbulence computations by including non-linear eddy viscosity based closures for both turbulent stresses and thermal flux. We extract the filtered PANS version of the Shih’s quadratic model (originally proposed for the Reynolds averaged Navier-Stokes (RANS) paradigm) for arriving at a PANS closure model for the turbulent stress tensor. The unclosed thermal flux process is modeled using the gradient diffusion hypothesis, wherein we sensitize the coefficient of diffusion to the presence of non-linear stresses in the formulation. The resulting methodology is evaluated by simulating flow past a heated square cylinder. Evaluations are performed in terms of both hydrodynamic variables and heat transfer characteristics. We find that the non-linear PANS methodology shows improved results in terms of hydrodynamic quantities (coefficient of drag, pressure, velocity profiles, and high-order statistics). While the predictions of the heat transfer rate on the front face of the cylinder are similar in the linear and the non-linear PANS methodologies, in the wake region and parts of the lateral wall where shear layer detachment takes place, the non-linear PANS methodology shows improved results.14531469S.SarohaApplied Mechanics Department, IIT Delhi, 110016, IndiaApplied Mechanics Department, IIT Delhi, 110016, Indiapayssagarsaroha18@gmail.comK.ChakrabortyApplied Mechanics Department, IIT Delhi, 110016, IndiaApplied Mechanics Department, IIT Delhi, 110016, Indiapayskrishnendu.bukai@gmail.comS. S.SinhaApplied Mechanics Department, IIT Delhi, 110016, IndiaApplied Mechanics Department, IIT Delhi, 110016, Indiapayssawan@am.iitd.ac.inS.LakshmipathyGexcon AS, Bergen, 5072, NorwayGexcon AS, Bergen, 5072, Norwaypaysl.sunil@gmail.comNon-linear eddy viscosity closure Scale resolving simulations Turbulent heat transfer Separated flows PANS.[Abdol-Hamid, K. S. and S. S. Girimaji (2004). A two-stage procedure toward the efficient implementation of pans and other hybrid turbulence models. NASA Technical Memorandum 213260.##
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]Large Eddy Simulation of a Turbulent Flow over Circular and Mixed Staggered Tubes’ Cluster22A large eddy simulation study was conducted to investigate the turbulent dynamic structure of a fluid flow in two staggered tube configurations, one is composed of all circular cylinders and the second is composed of circular and square cylinders. The present LES, based on the wall-adapting local eddy viscosity model, has been conducted for ReD = 12,858, which match available experiments. The appropriate grid has been selected using the grid convergence index method so that the wall-normal coordinate value is relevant for walls. Streamlines, turbulence kinetic energy contours, instantaneous vorticity contours computed indicate that wake patterns are more chaotic. In addition, flow coherent eddies within both configurations are identified via the -criterion. Based on the obtained findings, it can be stated that the model considered, in addition to being physically sound, demonstrated to be suitable for simulating the turbulent flow over circular and mixed staggered tube bundles with higher resolution.14711486M.BedrouniUniversity of Chlef, Laboratory of control, Testing, Measurement and Mechanical Simulation, B. P. 151, 2000 Chlef, AlgeriaUniversity of Chlef, Laboratory of control, Testing, Measurement and Mechanical Simulation, B. P. 151, 2000 Chlef, Algeriapaysmed.bedrouni@gmail.comA.KhelilUniversity of Chlef, Laboratory of control, Testing, Measurement and Mechanical Simulation, B. P. 151, 2000 Chlef, AlgeriaUniversity of Chlef, Laboratory of control, Testing, Measurement and Mechanical Simulation, B. P. 151, 2000 Chlef, Algeriapaysa.khelil@univ-chlef.dzM.BraikiaUniversity of Chlef, Laboratory of control, Testing, Measurement and Mechanical Simulation, B. P. 151, 2000 Chlef, AlgeriaUniversity of Chlef, Laboratory of control, Testing, Measurement and Mechanical Simulation, B. P. 151, 2000 Chlef, Algeriapaysbraikia_m@yahoo.frH.NajiUniversity of Artois, University of Lille, IMT Lille-Douai & Yncréa Hauts de France, (LGCgE-ULR 4515), F-62400 Béthune, FranceUniversity of Artois, University of Lille, IMT Lille-Douai & Yncréa Hauts de France, (LGCgE-ULR 4515), F-62400 Béthune, Francepayshassane.naji@univ-artois.frTube bundles Large eddy simulation Turbulent flow WALE model GCI method Q-criterion.[ANSYS Fluent Theory Guide - Fluent 18.1 (2017).##
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]A 2D Image-Based Approach for CFD Validation of Liquid Mixing in a Free-Surface Condition22This study proposes an image-based approach to evaluate the validity of numerical results for cases where the setup can be assumed to be two-dimensional (2D) and mixing between liquids of different densities occurs under a free-surface condition. The proposed methodology is based on the estimation of the relative errors of the model through density matrices generated from images of the experimental and numerical results (i.e., post-processing snapshots of the density field). To demonstrate the use of the methodology, experimental tests and numerical simulations were performed for a double-dam-break problem with two miscible liquids. For the experiments, a high-speed camera was employed to capture details of the fluid interactions after the dam breaking. For the numerical simulations, an OpenFOAM® multiphase solver was employed to reproduce the benchmarking tests. Three turbulence approaches were tested: a zero-equation RANS model, a two-equation (k-epsilon) RANS model, and a Large-Eddy Simulation (LES) model. The experimental results compared favorably against the numerical results, with averaged relative errors of ~17 and ~19 % for the zero-equation and the two-equation turbulence models, respectively, and ~14 % for the LES model. From the results obtained, it can be inferred that the two-equation (k-epsilon) model had limitations in reproducing the mixing between the liquid phases in terms of relative errors. The LES model reproduces the mixing between phases more accurately than zero and two-equation RANS models, which were seen to be more suitable for capturing the formation of large eddies in the initial phase of the experiment. The present methodology can be improved and extended for different multiphase flow configurations.14871500P. E.Rodríguez-OcampoInstitute of Engineering, National Autonomous University of Mexico (II-UNAM), Mexico City,04510, MexicoInstitute of Engineering, National Autonomous University of Mexico (II-UNAM), Mexico City,04510, Mexicopayselipao29@hotmail.comM.RingInstitute of Engineering, National Autonomous University of Mexico (II-UNAM), Mexico City,04510, MexicoInstitute of Engineering, National Autonomous University of Mexico (II-UNAM), Mexico City,04510, Mexicopaysmring@iingen.unam.mxJ. V.Hernández-FontesInstitute of Engineering, National Autonomous University of Mexico (II-UNAM), Mexico City,04510, MexicoInstitute of Engineering, National Autonomous University of Mexico (II-UNAM), Mexico City,04510, Mexicopaysjassiel.hernandez@gmail.comJ. C.Alcerreca-HuertaDepartment of Systematics and Aquatic Ecology, National Council of Science and Technology-The Southern Border College (CONACYT-ECOSUR), Chetumal, 77014, MexicoDepartment of Systematics and Aquatic Ecology, National Council of Science and Technology-The Southern Border College (CONACYT-ECOSUR), Chetumal, 77014, Mexicopaysjcalcerreca@conacyt.mxE.MendozaInstitute of Engineering, National Autonomous University of Mexico (II-UNAM), Mexico City,04510, MexicoInstitute of Engineering, National Autonomous University of Mexico (II-UNAM), Mexico City,04510, Mexicopaysemendozab@iingen.unam.mxG.Gallegos-Diez-BarrosoCoastal Processes and Physical Oceanography Laboratory, Department of Marine Resources, Center for Research and Advanced Studies of the National Polytechnic Institute (CINVESTAV), Merida, 97310, MexicoCoastal Processes and Physical Oceanography Laboratory, Department of Marine Resources, Center for Research and Advanced Studies of the National Polytechnic Institute (CINVESTAV), Merida, 97310, Mexicopaysmalhaya@gmail.comR.SilvaInstitute of Engineering, National Autonomous University of Mexico (II-UNAM), Mexico City,04510, MexicoInstitute of Engineering, National Autonomous University of Mexico (II-UNAM), Mexico City,04510, Mexicopaysrsilvac@iingen.unam.mxNumerical modelling Multiphase flow Liquid-liquid-gas interface flows Turbulence models Validation Dam-break experiments.[Afrasiabi, M., M. Roethlin and K. Wegener (2018). Thermal simulation in multiphase incompressible flows using coupled meshfree and particle level set methods. Comput. Methods Applied Mechanical Engineering 336, 667–694. ##
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]Enhancement of Liquid-Solid Two-Phase Flow Through a Vertical Swirling Pipe22In order to improve the transportation efficiency and safety of the vertical hydraulic transport pipe, a new type of pipeline transport system with helical blade is proposed in this paper. Based on CFD-DEM coupling method, the liquid-solid two-phase flow characteristics are analyzed for the swirling pipes and no blade pipe. The study focuses on the effect of the different helix angles of helical blade pipes in terms of the distributions of fluid velocity, the fluid vorticity, the total pressure, the particle’s local concentration, the drag force and kinetic energy of particles. Subsequently, the transport efficiency is measured based on the starting speed of particles and the particle concentration, and the safety of the particle transportation is evaluated based on the flow structure and the kinetic energy of particles. It is found that the tangential velocities of the swirling pipes are clearly larger than that of the case of no blade pipe, and the swirling number decreases as the increasing of helix angle of helical blades within swirling pipe. As the decreasing of helix angle, the vorticity magnitude increases sequentially, and the vortex core structure of the flow field is gradually enriched. Meanwhile, the total pressures for the swirling pipes decrease rapidly after the fluid enters the helical blades region, reflecting the difference energy efficiency of the swirling pipes. Furthermore, the swirling pipe accelerates the starting speed of the particle, and then increases the particle concentration in the pipe while making the particle spatial flow structure better and the particle kinetic energy larger. In general, the swirling pipe makes the particle transportation more efficient and safe.15011513J.YinSchool of Mechanical Engineering, Jiangsu University of Science and Technology, Zhenjiang 212000, ChinaSchool of Mechanical Engineering, Jiangsu University of Science and Technology, Zhenjiang 212000, Chinapaysyinjie@stu.just.edu.cnQ. Y.ChenDepartment of Metallurgy and Automotive Engineering, Shandong Vocational College of Industry, Zibo 256414, ChinaDepartment of Metallurgy and Automotive Engineering, Shandong Vocational College of Industry, Zibo 256414, Chinapaysqunyanc@163.comR.ZhuSchool of Environmental and Chemical Engineering, Jiangsu University of Science and Technology, Zhenjiang 212000, ChinaSchool of Environmental and Chemical Engineering, Jiangsu University of Science and Technology, Zhenjiang 212000, Chinapayszhurui@just.edu.cnW. X.TangSchool of Mechanical Engineering, Jiangsu University of Science and Technology, Zhenjiang 212000, ChinaSchool of Mechanical Engineering, Jiangsu University of Science and Technology, Zhenjiang 212000, Chinapayswenxiant@163.comS. J.SuSchool of Mechanical Engineering, Jiangsu University of Science and Technology, Zhenjiang 212000, ChinaSchool of Mechanical Engineering, Jiangsu University of Science and Technology, Zhenjiang 212000, Chinapayssushijie@just.edu.cnF.YanSchool of Mechanical Engineering, Jiangsu University of Science and Technology, Zhenjiang 212000, ChinaSchool of Mechanical Engineering, Jiangsu University of Science and Technology, Zhenjiang 212000, Chinapaysfyan716@163.comL. H.WangSchool of Mechanical Engineering, Jiangsu University of Science and Technology, Zhenjiang 212000, ChinaSchool of Mechanical Engineering, Jiangsu University of Science and Technology, Zhenjiang 212000, Chinapayswanglihui@just.edu.cnLiquid-solid two-phase Kinetic energy Swirling ﬂow CFD-DEM Vorticity.[Algifri, A. H., R. Bhardwaj and Y. V. N. Rao (1987). Prediction of the decay process in turbulent swirl flow. Proceedings of the Institution of Mechanical Engineers. Part C: Journal of Mechanical Engineering Science 201,279-283.##
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]Axial Gap Studies on the Flow Behavior and Performance of a Counter Rotating Turbine22A Counter Rotating Turbine (CRT) is an axial flow turbine with a nozzle followed by two rotors that rotate in the opposite direction of each other. Axial gap is an important parameter that affects the performance of turbine stage. Current work contains computationally analyzing the flow physics and performance of CRT with the axial gaps of 15, 30, 50 and 70% of the mean axial chord. Turbine components nozzle and the two rotors are modeled for all the axial gaps of CRT. At nozzle inlet, total pressure is taken as boundary condition and at rotor 2 outlet, mass flow rate is specified. Total pressure, entropy and TKE contours plotted at the inlet and outlet of the blade rows are utilized to analyze the effect of axial gap. Mass flow average distributions of entropy, TKE and relative stagnation pressure loss drawn at rotor 1 and rotor 2 outlets estimate the changes in flow losses with respect to axial gap. The intermediate axial gap of x/a = 0.3 is found to be beneficial for CRT for most of the flow rates. Also, it is found that the smallest and the largest gap cases are showing comparable performance. Thus, results confirm the influence of axial gap on the flow behavior and performance of CRT. 15151525R.SubbaraoDepartment of Mechanical Engineering, Indian Institute of Technology Madras, Chennai, 600036, IndiaDepartment of Mechanical Engineering, Indian Institute of Technology Madras, Chennai, 600036, Indiapaysrsubbarao@hotmail.comM.GovardhanDepartment of Mechanical Engineering, Indian Institute of Technology Madras, Chennai, 600036, IndiaDepartment of Mechanical Engineering, Indian Institute of Technology Madras, Chennai, 600036, Indiapaysgova@iitm.ac.inCounter rotating turbine (CRT) Axial gap Total pressure Entropy TKE Performance.[Dring, R. P., H. D. Joslyn and M. F. Blair (1987). The effect of inlet turbulence and rotor/stator interactions on the aerodynamics and heat transfer of large scale rotating turbine model. NASA Report, CR 179469. ##
Gaetani, P., G. Persico, V. Dossena and C. Osnaghi (2006). Investigation of the flow field in a hp turbine stage for two stator-rotor axial gaps, Part I-3D time-averaged flow field. ASME Turbo Expo 2006: Power for Land, Sea, and Air, Spain. ASME paper, GT 2006-90553, 659-668.##
Ji, L. C., X. B. Quan, L. Wel and J. Z. Xu (2001). A vaneless counter rotating turbine design towards limit of specific work ratio. ISABE paper 2001-1062. ##
Kikuchi, M., K. Funazaki, K. Yamada and H. Sato (2008). Detailed studies on aerodynamic performance and unsteady flow behaviors of a single turbine stage with variable rotor-stator axial gap. International Journal of Gas Turbine, Propulsion and Power Systems, 2(1), 30-37.##
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Yamada, K., K. Funazaki, M. Kikuchi and H. Sato (2009). Influences of axial gap between blade rows on secondary flows and aerodynamic performance in a turbine stage. ASME Turbo Expo 2009: Power for Land, Sea, and Air, Florida. ASME paper, GT 2009-59855, 1039-1049.##]Flow of a Thixotropic Bingham Fluid over a Cylinder in Stationary and Non-Stationary Regimes22Flow of a thixotropic Bingham liquid over a cylinder is investigated in this work. Thixotropy is a rheological characteristic associated with the microstructure of the material, which can be broken and recovered during a flowing process. Various flow characteristics such as the flow morphology, the unyielded/yielded zones, the microstructural state, and the hydrodynamic forces acting on the cylinder are analyzed at Re = 20–100 and Bn = 0.5–10. Comparison with Newtonian and non-thixotropic Bingham fluids are also carried out and discussed. Results show that, within these conditions, the flow spans from a stationary regime with or without separation to a non-stationary laminar one with von-Karman-type vortex shedding. In addition, no near-field unyielded zones are observed at Re = 100 and Bn = 0.5 and 1, probably due to the unsteady nature of the flow. At conditions where static unyielded zones exist, the wall shear stress normalized by the yield stress is minimum within these structures.15271538C. M.BuiFaculty of Engineering, Vietnamese-German University Le Lai Street, Hoa Phu Ward, Thu Dau Mot City, Binh Duong Province, VietnamFaculty of Engineering, Vietnamese-German University Le Lai Street, Hoa Phu Ward, Thu Dau Mot City, Binh Duong Province, Vietnampaysce2016_cuong.bm@student.vgu.edu.vnT. X.HoFaculty of Engineering, Vietnamese-German University Le Lai Street, Hoa Phu Ward, Thu Dau Mot City, Binh Duong Province, VietnamFaculty of Engineering, Vietnamese-German University Le Lai Street, Hoa Phu Ward, Thu Dau Mot City, Binh Duong Province, Vietnampaysthinh.hx@vgu.edu.vnBingham Thixotropy Computational fluid dynamics.[Barnes, H. A. (1997). Thixotropy—a review. Journal of Non-Newtonian Fluid Mechanics 70, 1–33.##
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Bui, C. M. and T. X. Ho (2019). Numerical study of an unsteady flow of thixotropic liquids past a cylinder. AIP Advances 9(11), 115002.##
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Mewis, J. and N. Wagner (2009). Thixotropy. Advances in Colloid and Interface Science 147, 214–227.##
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]Nanofluid Flow Comprising Gyrotactic Microorganisms through a Porous Medium22Researchers have significantly contributed to heat transfer field and always made out much effort to find new solutions of heat transfer augmentation. Among numerous methods which have been employed to reinforce the thermal efficiency of energy systems, one is the dispersal of gyrotactic microorganisms in commonly used nanofluids. Another way to improve the thermal efficiency is the utilization of the porous media. The present work deals with the study of nanofluid flow comprising gyrotactic microorganisms with allowance for chemical reaction through a porous medium past a stretching sheet. The nonlinear coupled ODEs are obtained after applying the persuasive tool of similarity transformation on governing model PDEs and then undertook numerically by exploiting the SOR (Successive over Relaxation) parameter method. The outcomes of assorted parameters for the flow are surveyed and discussed through graphs and tables. A comparison is correlated with the previously accomplished study and examined to be in an exceptional agreement. The culminations designate that the bioconvection Peclet number and the microorganisms concentration enhance the density of the motile microorganisms. The chemical reaction phenomenon downturns the concentration and enhances the mass transfer rate on sheet surface. The insertion of the gyrotactic microorganisms in the suspensions is widely used in the bio-microsystems. Examples include biotechnology (in order to enhance the transport phenomenon of heat and mass), enzyme biosensor and microfluidics devices like microvolumes and bacteria powered micromixers. The gyrotactic microorganisms also improve nanofluid stability. Microbial-enhanced oil recovery is also application of bioconvection phenomena where nutrients and microorganisms are inserted in oil bearing layer to maintain the variation in permeability. Our results may also be beneficial in improving the proficiency of microbial fuel cells and heat transfer devices.15391549S.AhmadCentre for Advanced Studies in Pure and Applied Mathematics, Bahauddin Zakariya University, Multan 60800, PakistanCentre for Advanced Studies in Pure and Applied Mathematics, Bahauddin Zakariya University, Multan 60800, Pakistanpayssohailkhan1058@yahoo.comM.AshrafCentre for Advanced Studies in Pure and Applied Mathematics, Bahauddin Zakariya University, Multan 60800, PakistanCentre for Advanced Studies in Pure and Applied Mathematics, Bahauddin Zakariya University, Multan 60800, Pakistanpaysmuhammadashraf@bzu.edu.comK.AliDepartment of Basic Sciences and Humanities, Muhammad Nawaz Sharif University of Engineering and Technology, Multan 60000, PakistanDepartment of Basic Sciences and Humanities, Muhammad Nawaz Sharif University of Engineering and Technology, Multan 60000, Pakistanpayskashifali_381@yahoo.comNanofluid Gyrotactic microorganisms Chemical reaction Concentration.[Acharya, N., D. Kalidas and P. K. Kundu (2016). Framing the effects of solar radiation on magneto-hydrodynamics bioconvection nanofluid flow in presence of gyrotactic microorganisms. Journal of Molecular Liquids 222, 28–37.##
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15611573W.LiDepartment of Mechanical Engineering, The University of Hong Kong, Hong KongDepartment of Mechanical Engineering, The University of Hong Kong, Hong Kongpaysliwenye@connect.hku.hkC. H.LiuDepartment of Mechanical Engineering, The University of Hong Kong, Hong KongDepartment of Mechanical Engineering, The University of Hong Kong, Hong Kongpayschliu@hku.hkW. C.ChengSchool of Atmospheric Sciences, Sun Yat-sen University, Guangzhou, PR ChinaSchool of Atmospheric Sciences, Sun Yat-sen University, Guangzhou, PR Chinapayszhengwzh7@mail.sysu.edu.cnAtmospheric flows Computational Fluid Dynamics (CFD) Internal Boundary Layer (IBL) Natural topography Surface-roughness change Turbulence characteristics.[Abkar, M. and F. Porté-Agel (2012). A new boundary condition for large-eddy simulation of boundary-layer flow over surface roughness transitions. J. Turbul., 13, N23.##
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Yoon, H. S., O. A. El-Samni, A. T. Huynh, H. H. Chun, H. J. Kim, A. H. Pham and I. R. Park (2009). Effect of wave amplitude on turbulent flow in a wavy channel by direct numerical simulation. Ocean Engineering 36(9-10), 697-707.##]Numerical Study of the Hydrodynamic Pressure Field Generated due to Ship Motion at Different Speeds22Ship movement in the shallow seas creates a significant hydrodynamic pressure field about the ship that has effect on the environmental structures such as waterway beds, stationary or moving neighbored vessels, and can also affect marine life. Therefore, the study of this phenomenon is very important in many applications. The present study investigated the hydrodynamic pressure field caused by an oil tanker with 247 m long, 53 m wide and 17 m draft moving at different speeds of 10, 15 and 20 knots on a sea level with a depth of 80 m. The fluid flow governing equations including the continuity equation, the momentum equations, and the K-ε turbulence model are solved numerically and the SIMPLE algorithm is used to correlate the pressure and velocity fields. An accurate Trimmer's structured mesh has been utilized to discrete the studied domain around the ship. To validate the methodology, the obtained dimensionless velocity field is compared with those presented by other works a good consistency is observed. As expected, the magnitude of the hydrodynamic pressure field varied as a function of the distance to the body of the vessel, ship's traveling velocity and magnitude of the draft. In this study, the minimum effects of the pressure were for the case of 10 knots (the minimum working velocity of heavy vessels) and 80 m of depth with a maximum pressure of 980 Pa. The results show that the pressure field dissipation occurs more rapidly in close distances to the vessel, and the pressure field domain decreases with a lower slope in far away from of the body. a hydrodynamic pressure correlation is obtained based on the depth and ship's velocity. Two and three-dimensional hydrodynamic pressure contours are also presented for different depths and velocities. Moreover, he hydrodynamic pressure increments in 12 and 7 m drafts are investigated and that shows after the 3/4 height of the bulbous bow lies below the sea surface, the increase in draft has little effect on the hydrodynamic pressure field.15751586A.NasseroleslamiFaculty of Mechanical Engineering, Shahrood University of Technology, Shahrood, Semnan, IranFaculty of Mechanical Engineering, Shahrood University of Technology, Shahrood, Semnan, Iranpaysamir.eslami@live.comA.SarreshtehdariFaculty of Mechanical Engineering, Shahrood University of Technology, Shahrood, Semnan, IranFaculty of Mechanical Engineering, Shahrood University of Technology, Shahrood, Semnan, Iranpayssarreshtehdari@gmail.comM.SalariDepartment of Mechanical Engineering, Imam Hussein University, Tehran, 1698715461, IranDepartment of Mechanical Engineering, Imam Hussein University, Tehran, 1698715461, Iranpaysm.salari@gmail.comHydrodynamic pressure field Draft Oil tanker CFD.[Begovic, E., C. Bertorello and S. Mancini (2015). Hydrodynamic performances of small size swath craft. Brodogradnja/Shipbuilding 66(4). 1-22.##
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Deng, H., Z. H. Zhang, J. B. Liu, and Ch. Wang (2017). Research on hydrodynamic pressure field causing by ship moving in mixed flow. Ocean Engineering 136, 314-321.##
Deng, H., Z. Zhang, J. Gu and J. Liu (2014). Numerical calculation and analysis of nonlinear pressure field induced by ship motion at subcritical speed in shallow water. Ship Building of China 55(1), 11-18.##
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]Numerical Investigation into the Effects of Tip Clearance on the Performance of a Counter-Rotating Axial Flow Compressor22The impact of varying the tip clearance of each rotor on the performance of a counter-rotating axial compressor has been investigated based on numerical simulations. The main purpose was to investigate the sensitivity to the tip clearance of each of the two individual rotors and the corresponding aerodynamic mechanisms associated with the performance variation in this compressor. The results indicated that both the total pressure ratio and the efficiency decreased as the tip clearance was increased, and the sensitivity curve for peak efficiency for both rotors was found to be an approximately linear negative relationship with increasing tip clearance. The variations of peak efficiency and stability margin of Rotor 2 were more sensitive to changing tip clearance than Rotor 1. An optimum combination of tip gaps existed for this compressor, i.e. 0.5τ for Rotor 1 and 0.25τ for Rotor 2 (where τ represents the nominal tip clearance value). At this optimum configuration, the peak efficiency and stability margin were improved by 0.63% and 29.4%, respectively. The location of the onset of the tip leakage vortex was found to be shifted downstream when the tip clearance increased. The nature of the tip leakage flow for each rotor was found to be influenced by the variation of tip clearance in the other rotor. Rotor 2 showed a more significant impact on Rotor 1. Additionally, varying the combination of tip clearances changed which of the two rotors was the first to stall.15871599T.LiangSchool of Power and Energy, Northwestern Polytechnical University, Xi’an, Shaanxi, 710072, P. R. ChinaSchool of Power and Energy, Northwestern Polytechnical University, Xi’an, Shaanxi, 710072, P. R. Chinapaysseakro@163.comB.LiuSchool of Power and Energy, Northwestern Polytechnical University, Xi’an, Shaanxi, 710072, P. R. ChinaSchool of Power and Energy, Northwestern Polytechnical University, Xi’an, Shaanxi, 710072, P. R. Chinapaysliubo704@nwpu.edu.cnS.SpenceSchool of Mechanical and Aerospace Engineering, Queen’s University Belfast, Belfast, BT9 5AH, UKSchool of Mechanical and Aerospace Engineering, Queen’s University Belfast, Belfast, BT9 5AH, UKpayss.spence@qub.ac.ukX.MaoSchool of Power and Energy, Northwestern Polytechnical University, Xi’an, Shaanxi, 710072, P. R. ChinaSchool of Power and Energy, Northwestern Polytechnical University, Xi’an, Shaanxi, 710072, P. R. Chinapaysmaoxiao_chen@126.comH.ChengSchool of Power and Energy, Northwestern Polytechnical University, Xi’an, Shaanxi, 710072, P. R. ChinaSchool of Power and Energy, Northwestern Polytechnical University, Xi’an, Shaanxi, 710072, P. R. Chinapaysseakro@outlook.comCounter-rotating compressor Tip clearance Efficiency Tip leakage flow Absolute vorticity.[Anson, M. and L. Zhang (1995). On-site graphics for planning and communicating the use of site space. In Y. Loo (Ed.), Proceed¬ings of the Fifth East Asia-Pacific Conference on Structural Engineering and Construction, Gold Coast, Australia, 883-888. Griffith University.##
Berdanier, R. and N. Key (2016). The effects of tip leakage flow on the performance of multistage compressors used in small core engine applications. Journal of Engineering for Gas Turbines and Power 138, 052605.##
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Domercq, O. and J. F. Escuret (2007) Tip clearance effect on high-pressure compressor stage matching, Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 221(6), pp. 759–767.##
Du, H., X. Yu, Z. Zhang and B. Liu (2013). Relationship between the flow blockage of tip leakage vortex and its evolutionary procedures inside the rotor passage of a subsonic axial compressor. Journal of Thermal Science 22: 522–531.##
Gao, L., X. Li, X. Feng and B. Liu (2012). The effect of tip clearance on the performance of contra-rotating compressor. ASME Paper No. GT2012-68801.##
Hoying, D., C. Tan, H. Vo and E. Greitzer (1999). Role of blade passage flow structurs in axial compressor rotating stall inception. Journal of Turbomachinery 121(4), 735-742.##
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Wang, Y., W. Chen, C. Wu and S. Ren (2015). Effects of tip clearance size on the performance and tip leakage vortex in dual-rows counter-rotating compressor. Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering 229(11), 1953–1965.##
Yamada, K., H. Kikuta, M. Furukawa, S. Gunjishima and Y. Hara (2013). Effects of tip clearance on the stall inception process in an axial compressor rotor. ASME Paper No. GT2013-95479.##]Numerical Simulation of Supersonic Flow through Scramjet Intake with Concavity in Cowl Surface22Scramjet intake usually employs shock waves to reduce the flow velocity and increases the static pressure of the flow. However, this causes flow separation and multiple reflections of shock waves, which result in total pressure loss for the flow. This paper discusses the performance enhancement of scramjet intake through the implementation of a concavity along the cowl surface. The baseline intake model used here is the same as that reported in Emami et al. (1995) Two models with the concavities of depth 0.05 and 0.1 inches on cowl inner surface are numerically simulated at Mach number 4.03, and compared with the base model. An improvement in the performance is investigated in terms of total pressure and flow separation. Present study shows that a concavity on cowl surface reduces the flow separation on the ramp wall and increases the total pressure when compared to the base case. This is achieved by expansion fans produced at the beginning of the concavity. These expansion fans weaken the cowl lip shock and suppress the separation size. Further, it turns the shock waves along the flow, decreasing the number of shock wave reflections in the isolator. Thus, increase in total pressure at the exit of the isolator is observed. It is found that there is a marginal increase in Mach number for both the concavity cases without any change in mass flow rate. There was a minor flow distortion observed, which may be corrected by changing the isolator length. This study demonstrates the scope of overall improvement in scramjet engine performance by implementing concavity along the cowl surface.16011610P.SenthilkumarDepartment of Aerospace Engineering, Indian Institute of Technology, Madras – 600036, IndiaDepartment of Aerospace Engineering, Indian Institute of Technology, Madras – 600036, Indiapayssenthilp76@gmail.comT. M.MuruganandamDepartment of Aerospace Engineering, Indian Institute of Technology, Madras – 600036, IndiaDepartment of Aerospace Engineering, Indian Institute of Technology, Madras – 600036, Indiapaysmurgi@ae.iitm.ac.inScramjet intake Concavity Flow distortion Expansion fans Shock wave boundary layer interaction Total pressure recovery.[Creighton, S. and R. Hillier (2007). Experimental and computational study of unsteady hypersonic cavity flows. The Aeronautical Journal 111(1125), 673–688.##
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]A Semi-Coupled Model for Morphological Flow Simulation in River Bend22This paper presents a new efficient and robust numerical model for morphological flow simulation in river bends. The hydrodynamic model is developed by solving the two dimensional (2D) shallow water equations using a total variation diminishing (TVD) MacCormack predictor corrector scheme. The present TVD method is very simple and provides accurate results free from numerical oscillations near sharp gradient. The effective stresses are modeled by using a constant eddy viscosity model. The sediment transport model solves the Exner equation using a simple forward time and central space (FTCS) finite difference algorithm. The sediment transport model incorporates the helical flow and the transverse bed slope effects on the sediment direction computation. These models are coupled using the semicoupled approach. The present semicoupled model is used to replicate two popular experimental test cases of both tight and loose channel bends. The obtained results in terms of bed level variation reveal that the model can accurately simulate several features of the bed changes such as oscillations of the transverse bed profile with the formation of point bars and pools along the banks. The values obtained for three widely used statistical parameters show the applicability of the present model for this type of complex scenarios. 16111622K.BoraDepartment. of Civil Engineering., National Institite of Technology, Meghalaya, Shillong,793003, IndiaDepartment. of Civil Engineering., National Institite of Technology, Meghalaya, Shillong,793003, Indiapayskbora.0757@gmail.comH. M.KalitaDepartment. of Civil Engineering., National Institite of Technology, Meghalaya, Shillong,793003, IndiaDepartment. of Civil Engineering., National Institite of Technology, Meghalaya, Shillong,793003, Indiapayshriday@nitm.ac.inShallow water equations Exner equation TVD MacCormack scheme FTCS scheme Semi-coupled model Sediment transport model. [Abad, J. D., G. C. Buscaglia and M. H. Garcia (2008). 2d stream hydrodynamic, sediment transport and bed morphology model for engineering applications. Hydrological Processes: An International Journal 22(10), 1443–1459.##
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]Comparison Aerodynamic Performance and Power Fluctuation Between Darrieus Straight-Bladed and Gorlov Vertical Axis Wind Turbines22All human actions necessitate energy resources. Currently, a major part of our energy requirements is supplied by fossil fuels, which are faced with uncertainties concerning their availability in the forthcoming decades. However, the combustion of fuels results in adverse environmental aftermaths. Energy of wind falls into one of the clean and renewable energy resources. Wind power is generated using horizontal and vertical axis wind turbines (HAWTs & VAWTs). VAWTs operate appropriately under low wind velocity conditions to generate power in small scales. On the other hand, numerous VAWT designs have been presented to enhance their performance in such circumstances. This study is aimed at developing cost-effective aerodynamic calculations models for both Gorlov and Darrieus straight-bladed VAWT types. Thus, DMST (double multiple stream tube) models, which act on the basis of BEM (blade element momentum) theory, have been designed for Gorlov and Darrieus VAWTs. By comparison of the results obtained with those available in the literature, the models developed are validated. Additionally, the performance of the Darrieus-type straight-bladed VAWTs was compared to that of the Gorlov VAWTs. According to the findings, although the peak power coefficient (C_P) decreased slightly for Gorlov VAWTs in comparison with the Darrieus straight-bladed type, the Gorlov rotor showed improved performance in terms of fluctuation and effectiveness based on the torque coefficient curve of helical blades.16231633M.MoghimiSchool of Mechanical Engineering, Iran University of Science & Technology, Tehran, IranSchool of Mechanical Engineering, Iran University of Science & Technology, Tehran, Iranpaysmoghimi@iust.ac.irH.MotawejSchool of Mechanical Engineering, Iran University of Science & Technology, Tehran, IranSchool of Mechanical Engineering, Iran University of Science & Technology, Tehran, Iranpaysh_motawej@mecheng.iust.ac.irDarrieus VAWT DMST Gorlov power fluctuation Aerodynamic performance.[Abdul Akbar, M. and V. Mustafa (2016). A new approach for optimization of Vertical Axis Wind Turbines. Journal of Wind Engineering and Industrial Aerodynamics 153, 34–45.##
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]A Numerical Approach for Simulating a High-Speed Train Passing through a Tornado-Like Vortex22Tornados are one of the most common natural disasters, but their occurrence can be sudden and unpredictable. For trains operating in the areas where tornadoes frequently happen, the operation safety is challenged. Tornado generator was recently proposed as a method of numerical investigation of tornado-like vortex flows. This paper presents a numerical approach for the simulation of train passing through a tornado-like vortex on realistic scale. It is found that the tornado-like vortex causes appearance of localized regions of a negative pressure on the train and transient variations of the aerodynamic loads acting on the train. As a result, the tornado-like vortex causes swings on the lateral force, and subsequently on the rolling moment, which affect the passenger comfort and operation safety of the train. The method presented herein can be further applied to the study of train behavior and real time response while encountering tornadoes of different types and strength, which is significant for evaluating the operation safety of high-speed trains.16351648R. Z.XuKey Laboratory of Traffic Safety on Track, Ministry of Education, School of Traffic & Transportation Engineering,Central South University, Changsha 410075, Hunan, ChinaKey Laboratory of Traffic Safety on Track, Ministry of Education, School of Traffic & Transportation Engineering,Central South University, Changsha 410075, Hunan, Chinapaysaaa73993.14@163.comF.WuJoint International Research Laboratory of Key Technologies for Rail Traffic Safety, Changsha 410075, Hunan, ChinaJoint International Research Laboratory of Key Technologies for Rail Traffic Safety, Changsha 410075, Hunan, Chinapaysgszxcfd_wf@csu.edu.cnW. H.SuNational & Local Joint Engineering Research Center of Safety Technology for Rail Vehicle, Changsha 410075, Hunan, ChinaNational & Local Joint Engineering Research Center of Safety Technology for Rail Vehicle, Changsha 410075, Hunan, Chinapays184212087@csu.edu.cnJ. F.DingDepartment of Applied Mathematics, University of Waterloo, Ontario N2L3G1, CanadaDepartment of Applied Mathematics, University of Waterloo, Ontario N2L3G1, Canadapaysj35ding@edu.uwaterloo.caD.VainchteinNyheim Plasma Institute, Drexel University, Camden, NJ, USANyheim Plasma Institute, Drexel University, Camden, NJ, USApaysdlvainchtein@gmail.comTornado-like vortex High-speed train Train aerodynamic Fluid-solid interaction Train safety.[Alexander, C. R. and J. Wurman (2004). The 30 may 1998 spencer, south dakota, storm. part i: The structural evolution and environment of the tornadoes. Monthly Weather Review133(133), 72–97.##
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]Non-orthogonal Multiple-Relaxation-Time Lattice Boltzmann Simulation of Mixed Convection in Lid-Driven Porous Cavity with an Isothermally Heated Block22Laminar mixed convection in porous cavity with an isothermally heated block had been investigated numerically by using Non-orthogonal multiple-relaxation time lattice Boltzmann method (MRT-LBM). The effects of six different arrangements of the cold sources on the characteristics of fluid flow and heat transfer had been studied. Another important influencing factor was the direction of lid-driven. We investigated the effects of four different lid-driven directions on fluid flow and heat transfer when the top and bottom walls of the cavity maintained constant cold temperature. The results show that different arrangements of the cold sources produce different numbers of vortices with the Richardson number increases. As for Top-Left, Top-Right and Top-Bottom arrangements, these three arrangements always show high heat teansfer level. Additionally, the right-moving top and bottom walls exhibits best heat transfer characteristic than other three cases when Ri≤1, and the case of top and bottom walls moves in the opposite directions has best heat transfer performance than other three cases when Ri＞1. When the cold sources are arranged on the upper wall of the cavity, it shows better heat transfer performance.16491662Y.ZhangSchool of Mechanical and Electrical Engineering, Nanchang University, Nanchang 330031, ChinaSchool of Mechanical and Electrical Engineering, Nanchang University, Nanchang 330031, Chinapaysyzhan2033@163.comJ.BaoSchool of Mechanical and Electrical Engineering, Nanchang University, Nanchang 330031, ChinaSchool of Mechanical and Electrical Engineering, Nanchang University, Nanchang 330031, Chinapays1569255263@qq.comM.YaoSchool of Mechanical and Electrical Engineering, Nanchang University, Nanchang 330031, ChinaSchool of Mechanical and Electrical Engineering, Nanchang University, Nanchang 330031, Chinapays1528181961@qq.comY.XieSchool of Mechanical and Electrical Engineering, Nanchang University, Nanchang 330031, ChinaSchool of Mechanical and Electrical Engineering, Nanchang University, Nanchang 330031, Chinapays1448522851@qq.comY.HuangSchool of Mechanical and Electrical Engineering, Nanchang University, Nanchang 330031, ChinaSchool of Mechanical and Electrical Engineering, Nanchang University, Nanchang 330031, Chinapays781444545@qq.comP.LiSchool of Mechanical and Electrical Engineering, Nanchang University, Nanchang 330031, ChinaSchool of Mechanical and Electrical Engineering, Nanchang University, Nanchang 330031, Chinapaysncudns1995z@163.comLattice Boltzmann method Mixed convection Lid-driven cavity Porous media Isothermally heated block. [Al-Amiri, A. M. (2000). Analysis of momentum and energy transfer in a lid-driven cavity filled with a porous isothermally heated block. International Journal of Heat and Mass Transfer 43(19),3513-3527.##
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]Concentration Modulation Effect on Weakly Nonlinear Thermal Instability in a Rotating Porous Medium22The present article is to study mass transfer in a rotating porous layer subjected to imposed time-periodic solutal boundaries. A weakly nonlinear analysis is applied to investigate mass transfer in a porous medium. The mass transfer coefficient is calculated by cubic Ginzburg Landau (GLE) amplitude equation. In this article the stationary convection is discussed in the presence of rotating solutal Rayleigh number. The amplitude equation (GLE) is solved numerically to calculate finite temporal convective amplitude. This amplitude is used to find Sherwood number in terms of the various system parameters. The effect of individual parameters on mass transport is discussed in detail in the presence of lower rotational rates. The onset of convection is discussed through the stability curves for stationary and oscillatory solutal critical Rayleigh number as a function of wavenumber. Further, it is found that the mass transfer enhances for modulated system than un-modulated system. Internal solutal number Si is to enhances for higher values and diminishes the mass transfer for lower values. Finally, it is also found that rotation and solutal modulation can be effectively used to enhance or diminish the mass transfer.16631674P.KiranDepartment of Mathematics, Chaitanya Bharathi Institute of Technology, Gandipet, Hyderabad, Telangana-500075, India.Department of Mathematics, Chaitanya Bharathi Institute of Technology, Gandipet, Hyderabad, Telangana-500075, India.payskiran40p@gmail.comDarcy convection Concentration modulation Rotation Nonlinear theory.[Bhadauria, B. S. (2007). Double diffusive convection in a rotating porous layer with modulated temperature on the boundaries. Journal of Porous Media 10(6), 569−584.##
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