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Turbulence Structures in Accelerated Flow over a Flat Plate with Non-Zero Pressure Gradient
Author(s): Mehrnoush Kharghani, mahmuod Pasandidehfard
Keywords: Turbulent Flow; Temporal acceleration; Instability; Boundary Layer; Pressure gradient; Turbulence kinetic energy; Spatially acceleration
The numerical simulation of temporally accelerated flow subjected to Favorable and Adverse Pressure Gradients (FPG & APG) is represented, while two extreme accelerations are considered to impose on the fully turbulent flow over a flat plate. The γ-SST model is implemented in order to define the boundary layer development, turbulence structures, and the wall functions response to the external accelerated flow. The obtained results illustrate that the FPG condition accompanied by temporal acceleration, can damp the fluctuations severely and an almost-laminar boundary layer is developed near the wall which is followed by the retransition to the higher turbulent state. However, the APG condition causes higher turbulence diffusion in a temporal accelerated flow and makes the flow more orderly and stabilized, although the re-laminarization is observable in this region excessively. Moreover, applied condition disturbs the Reynolds stress correlation and generates semi-elliptic eddies shape, because acceleration affects wall-normal fluctuations more than the streamwise ones. In addition, a new acceleration parameter for this condition is represented which has been compared to the acceleration parameter in spatially accelerated flow.

Journal of Applied Fluid Mechanics

The Journal of Applied Fluid Mechanics (JAFM) is an international, peer-reviewed journal which covers a wide range of theoretical, numerical and experimental aspects in fluid mechanics. The emphasis is on the applications in different engineering fields rather than on pure mathematical or physical aspects in fluid mechanics. Although many high quality journals pertaining to different aspects of fluid mechanics presently exist, research in the field is rapidly escalating.

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