Turbulence modeling of mixing layers under anisotropic strain

The compression or expansion of turbulent mixing layers often occurs under anisotropic strain rates, causing the mixing layer to compress or expand at different rates in different directions. Anisotropic strain patterns are common in nozzle flows and implosions yet are rarely addressed in turbulence models. The treatment of the turbulent length scale under bulk compression is investigated for a two-equation Reynolds---Averaged Navier---Stokes model. Comparing to strained implicit large eddy simulations, the mixing layer properties are better predicted when accounting for the alignment of the strain rates and the mixing layer growth direction.