We investigate the eﬀectiveness of the semi-local Reynolds number Re τ to parametrize wall-bounded ﬂows with strong density, ρ, and viscosity, µ, gradients. Several cases are considered, namely, volumetrically heated low-Mach-number turbulent channel ﬂows, a simultaneously heated and cooled ﬂow with CO2 at supercritical pressure, and heated and cooled supersonic boundary layer ﬂows. The mean density and viscosity in some of these cases vary up to a factor of nine and six, respectively. We show that, even for such high gradients in mean properties, the velocity transformation based on the semi-local Reynolds number is able to collapse the mean streamwise velocity proﬁles. We further-more provide evidence that the turbulent kinetic energy and streamwise vorticity budget equations are also governed by the semi-local Reynolds number. For cases with strong property variations, additional mechanisms appear that are caused by individual density (e.g., baroclinicity) or viscosity gradients. However, in the cases investigated herein, these additional mechanisms are small. The insights gained are used to improve a wall model, which is then tested in a wall-modeled large-eddy simulation (LES) of a compressible channel ﬂow with isothermal walls.
|Title of host publication||Proceedings of the 2016 Summer Program|
|Subtitle of host publication||Studying Turbulence Using Numerical Simulation Databases - XVI|
|Publisher||Center for Turbulence Research, Stanford University, USA|
|Publication status||Published - 2017|
|Event||Studying Turbulence Using Numerical Simulation Databases - XVI: 2016 Summer Program - Stanford, United States|
Duration: 26 Jun 2016 → 22 Jul 2016
Conference number: 16
|Conference||Studying Turbulence Using Numerical Simulation Databases - XVI|
|Period||26/06/16 → 22/07/16|
Patel, A., Pecnik, R., Peeters, J., Boersma, B. J., Hickel, S., & Moghadam, M. E. (2017). Turbulence modulation by variable density and viscosity. In Proceedings of the 2016 Summer Program: Studying Turbulence Using Numerical Simulation Databases - XVI (pp. 213-222). Center for Turbulence Research, Stanford University, USA.