Open Access

ARTICLE

Large Eddy Simulation of Turbulent-Supersonic Boundary Layer Subjected to Multiple Distortions

W. A. El-Askary¹

1 Mechanical Power Engineering Department, Faculty of Engineering, Menoufiya University, She-bin El-Kom, Egypt. Corresponding author, Tel.: +2-0105255817, +2-048-3486965; Fax: +2-048-2235695. Email address: wageeh_elaskary@yahoo.com

Computer Modeling in Engineering & Sciences 2011, 74(3&4), 203-232. https://doi.org/10.3970/cmes.2011.074.203

Abstract

Large eddy simulation (LES) is a viable and powerful tool to analyze unsteady three- dimensional turbulent flows. In this paper, the method of LES is used to compute a plane turbulent supersonic boundary layer subjected to different pressure gradients. The pressure gradients are generated by allowing the flow to pass in the vicinity of an expansion-compression ramp (inclined backward-facing step with leeward-face angle of 25 degrees) for an upstream Mach number of 2.9. The inflow boundary condition is the main problem for all turbulent wall-bounded flows. An approach to solve this problem is to extract instantaneous velocities, temperature and density data from an auxiliary simulation (inflow generator). To generate an appropriate realistic inflow condition to the inflow generator itself the rescaling technique for compressible flows is introduced. In this method Morkovin's hypothesis in which the total temperature fluctuations are neglected compared with the static temperature fluctuations is applied to rescale and generate the temperature profile at inlet. This technique was successfully developed and applied by the present author for a large eddy simulation of subsonic three-dimensional boundary layer of a smooth curved ramp.
The present LES results are compared with the available experimental as well as numerical data. The positive impact of LES is proven by the convincing agreement of the obtained results with the experimental data compared with published numerical work and sheds the light on the quality of the compressible inflow generator method.

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