A Modified Gas-Kinetic Scheme for Turbulent Flow
Marcello Righi 1*1 School of Engineering, Zurich University of Applied Sciences, Technikumstrasse 9, 8401 Winterthur, Switzerland.
Received 14 August 2013; Accepted (in revised version) 2 December 2013
Available online 16 April 2014
The implementation of a turbulent gas-kinetic scheme into a finite-volume RANS solver is put forward, with two turbulent quantities, kinetic energy and dissipation, supplied by an allied turbulence model. This paper shows a number of numerical simulations of flow cases including an interaction between a shock wave and a turbulent boundary layer, where the shock-turbulent boundary layer is captured in a much more convincing way than it normally is by conventional schemes based on the Navier-Stokes equations. In the gas-kinetic scheme, the modeling of turbulence is part of the numerical scheme, which adjusts as a function of the ratio of resolved to unresolved scales of motion. In so doing, the turbulent stress tensor is not constrained into a linear relation with the strain rate. Instead it is modeled on the basis of the analogy between particles and eddies, without any assumptions on the type of turbulence or flow class. Conventional schemes lack multiscale mechanisms: the ratio of unresolved to resolved scales - very much like a degree of rarefaction - is not taken into account even if it may grow to non-negligible values in flow regions such as shocklayers. It is precisely in these flow regions, that the turbulent gas-kinetic scheme seems to provide more accurate predictions than conventional schemes.
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PACS: 47.27.em, 47.27.nb, 47.32.Ff, 47.40.Hg, 47.40.Nm, 47.45.Ab, 47.85.Gj, 47.85.ld
Key words: Gas kinetic theory, turbulence modeling, compressible flow, shock boundary layer interaction.
Email: firstname.lastname@example.org (M. Righi)