

Applications of Hydraulic Properties Models on Microscopic Flow in Unsaturated Porous Media


Pages :
111


Authors :
T. Bunsri,
M. Sivakumar,
D. Hagare,
Several existing equations for solving the nonlinear soilhydraulic properties are introduced and validated to field and
laboratory measured data. Models for nonlinear hydraulic properties of unsaturated porous media arise from statistical
and mathematical fit through the measured data and they can be expressed in forms of unsaturated permeability versus
either pressure head or volumetric moisture content. This paper presents the difference models: Gardner, Knuze et al.,
Haverkamp et al., van Genuchten and Saxton et al. for calculation of hydraulic properties coefficients, typically
unsaturated permeability. The accurate and computational efficiency of these five existing models are evaluated for a
series of study cases simulating hydraulic properties of unsaturated porous media. The results indicate that all existing
models can be applied to homogenous and heterogenous unsaturated porous media, dry and wet cycles and laboratory
and field measuring data. Besides, the statistical fit model is inefficient compared to mathematical fit models. Among
the mathematical fit models, van Genuchten model is the most promising model. Gardner model can be competitive
with van Genuchten model and Haverkamp et al. model is less efficient than others. The mathematical fit models
appear to be attractive alternatives to estimate the unsaturated permeability, although there are concerns regarding the
stability behaviour of the occupied air in pores, which need to be resolved. The air movement in unsaturated porous
media affected the unsaturated permeability, which gives the difference results between wet and dry cycle. Both of
unsaturated permeability and volumetric water content of dry cycle were higher than ones of wet cycle. This suggests
that the velocity of airreleasing during a wet process was higher than the velocity of airentering during a dry process.
The infiltration is the most important land applications. So, the wet cycle hydraulic properties test might be concerned.
Moreover, most of infiltration fields locate on the mixed grain media. So too, the poresize distribution could affect the
unsaturated permeability of porous media. It was observed that the finer material, the lower unsaturated permeability.





Vortical Flow Topology on Windward and Leeward side of Delta Wing at Supersonic Speed


Pages :
1321


Authors :
Y. Younis,
A. Bibi,
A. U. Haque,
S. Khushnood,
area of interest for flow control due to coherent vortical structures existing on the leeward side of wing. In the present
research, a numerical study was carried out by using two different turbulence models at Mach No. 1.6, to identify the
influence of turbulence modeling and wing on overall pressure distribution and onset of flow separation. Fully
structured multiblock grid was used with the grid refinement near the wall to resolve the vortical flow structures
accurately. Different turbulence models used were SA (SpalartAllmaras) and kωSST (Shearstress Transport). An
under prediction in pressure distribution was observed by using SA Turbulence model, in comparison with known
experimental data at fixed Mach No. The analysis of results presented showed that the height of primary vortex
increases by increasing the angle of attack and by keeping the Mach No. as fixed. Moreover, the vortex formation on
cambered wing seems less pronounced as compared with that of sharp wing at high angle of attack.





Numerical Investigation of Flow in a New DC Pump MHD


Pages :
2328


Authors :
N. Bennecib,
S. Drid,
R. Abdessemed,
Electromagnetic pumps have several advantages to mechanical pumps. They offer maneuverability by directional thrust
along with quietness and are conceived with an aim of eliminating all moving parts, being also free from problems of
wear and tiredness of use. The flow field in the channel is treated as steady state, incompressible and fully developed
laminar flow conditions. Our numerical code DCPMHD uses cylindrical coordinates (r,ϕ , z) and solves the
incompressible MHD equations for magnetic vector potential A and fluid velocity V. Using finite volume method for
numerical calculation. The numerical results of the performance characteristics of a DC electromagnetic pump are
discussed and show that our new concept is capable to deliver bidirectional activation and have a satisfactory
controllability, because of its proportional output force and input current relationship.





Effects of Radiation and Variable Fluid Viscosity on Flow and Heat Transfer along a Symmetric Wedge


Pages :
2934


Authors :
S. Mukhopadhyay,
Radiation effects on boundary layer flow and heat transfer of a fluid with variable viscosity along a symmetric wedge is
presented here. Fluid viscosity is assumed to vary as a linear function of temperature. The symmetry groups admitted
by the corresponding boundary value problem are obtained by using a special form of Lie group transformations viz.
scaling group of transformations. A third order and a second order coupled ordinary differential equation system
corresponding to the momentum and the energy equations are obtained. These equations are then solved numerically.
With the increase of temperaturedependent fluid viscosity parameter (i.e. with decreasing viscosity), the fluid velocity
increases up to the crossover point (η =η0 ) (η0 ≈ 0.90 is the nearest numerical value of the crossover point) and
after the crossing over point the fluid velocity is found to decrease but the temperature increases at a particular point.
The significant finding of this study is that, due to variable fluid viscosity, flow separation is controlled. The
temperature decreases with increasing value of radiation parameter and Prandtl number.





HydroGravitational Dynamics of Planets and Dark Energy


Pages :
3541


Authors :
C. H. Gibson,
R. E. Schild,
Self gravitational fluid mechanical methods termed hydrogravitationaldynamics (HGD) predict plasma fragmentation
0.03 Myr after the turbulent big bang to form protosuperclustervoids, turbulent protosuperclusters, and protogalaxies at
the 0.3 Myr transition from plasma to gas. Linear protogalaxyclusters fragment at 0.003 Mpc viscousinertial scales
along turbulent vortex lines or in spirals, as observed. The plasma protogalaxies fragment on transition into whitehot
planetmass gas clouds (PFPs) in millionsolarmass clumps (PGCs) that become globularstarclusters (GCs) from tidal
forces or dark matter (PGCs) by freezing and diffusion into 0.3 Mpc halos with 97% of the galaxy mass. The weakly
collisional nonbaryonic dark matter diffuses to > Mpc scales and fragments to form galaxy cluster halos. Stars and
larger planets form by binary mergers of the trillion PFPs per PGC, mostly on 0.03 Mpc galaxy accretion disks. Stars
deaths depend on rates of planet accretion and internal star mixing. Moderate accretion rates produce white dwarfs
that evaporate surrounding gas planets by spinradiation to form planetary nebulae before Supernova Ia events,
dimming some events to give systematic distance errors, the dark energy hypothesis, and overestimates of the universe
age.





A Study of DC Surface Plasma Discharge in Absence of Free Airflow: Ionic Wind Velocity Profile


Pages :
4348


Authors :
M. Rafika,
H. Ramzi,
B. N. Sassi,
In our study we are interested with the DC (Direct Current) electric corona discharge created between two wire
electrodes. We present experimental results related to some electroaerodynamic actuators based on the DC corona
discharge at the surface of a dielectric material. We used different geometrical forms of dielectric surface such as a
plate, a cylinder and a wing of aircraft of type NACA 0015. We present the current densityelectric filed characteristics
for different cases in order to determine the discharge regimes. The corona discharge produces nonthermal plasma so
that it is called plasma discharge. Plasma discharge creates a tangential ionic wind above the surface at the vicinity of
the wall. We have measured the ionic wind induced by the corona discharge in absence of free external airflow, we give
the ionic wind velocity profiles for different surface forms and we compare the actuators effect based on the span of the
ionic wind velocity values. We notice that the maximum ionic wind velocity is obtained with the NACA profile, which
shows the effectiveness of this actuator for the airflow control.





Mechanical Effects in PEM Fuel Cell: Application to Modeling of Assembly Procedure


Pages :
4954


Authors :
S. Martemianov,
M. Gueguen,
J. C. Grandidier,
D. Bograchev,
Mechanical effects can influence significantly electrical performance and life time of PEM fuel cells. A linear elasticplastic
2D model of fuel cell with hardening is used for modeling of assembly procedure of fuel cells. The model
simulates mechanical behavior of the main components of real fuel cell (the membrane, the gas diffusion layers, the
graphite plates, and the seal joints) and clamping elements (the steel plates, the bolts, the nuts). The stress and plastic
deformation in MEA have been calculated using ABAQUS code. The results are presented on the local and the global
scales with respect to the realistic clamping conditions. The first one corresponds to the single tooth/channel structure.
The global scale deals with features of the entire cell and takes into account the border effects, in particular the
influence of seal joints.





Electricity Generation from Low Temperature Sources


Pages :
5567


Authors :
N. Galanis,
E. Cayer,
P. Roy,
E. S. Denis,
M. Désilets,
Power plants using conventional processes and unconventional fluids have a significant potential for the valorization of
low and medium temperature renewable energy sources as well as waste heat from industrial, commercial or
institutional installations. This review paper describes some prototypes of such power plants and summarizes some of
the relevant scientific and technical literature. An analysis based on the first and second laws of thermodynamics and
basic heat transfer relations is used to illustrate the operational limits and performance characteristics of these power
plants.





Impact of the Automotive Aerodynamic Control on the Economic Issues


Pages :
6975


Authors :
A. Kourta,
P. Gilliéron,
Sustainable development associated with the need to reduce the energy consumption and to offer more creative freedom
to the automobile designers requires looking for new solutions of control without appendix added nor geometrical
modification. Among these solutions, the active flow control by fluidic actuators constitutes an interesting alternative.
Various configurations of control are thus tested in order to reduce the aerodynamic drag. The results show that
protocols based on control by suction, blowing or intermittent jet allows reducing the aerodynamic drag and
consequently the consumption and CO2 emissions.





A Novel 2D BEM with Composed Elements to Study Sloshing Phenomenon


Pages :
7783


Authors :
M. Abbaspour,
M. G. Hassanabad,
In the Boundary Element Method (BEM), the corner elements make some difficulties in the numerical method. It means
that, the results of BEM solution with linear elements are more accurate than constant elements inherently, but the
difference between boundary conditions of one corner node from two adjacent boundaries causes to increase errors in
linear element in comparison of constant element. In this article, a new approach of BEM discretizing has been
introduced for simulating water sloshing in a 2D rectangular container which augments the accuracy. The time history
of free surface shape has been obtained by applying Finite Difference Method (FDM) for free surface boundary
conditions and BEM direct method with constant, linear and a novel element which has been named composed element
in this study. Composed elements have been proposed for solving corner nodes problem. It means that all of the
elements are linear except common nodes in two adjacent boundaries which are selected constant. This solution causes
to decrease the number of elements for an acceptable precision and hence the time considerably saves potential flow
and small amplitude water wave assumptions were applied in the present research. The results of this analysis
illustrated acceptable agreement with other articles results with large dimension and small amplitude water wave
assumptions. As a final point, the accuracy of results increased respect to linear, constant and composed elements.





