Turbulence mixing length for compressible free shear flows

Seizing compressible flow variable density characteristics, a three-dimensional von Karman mixing length scale based on the effective vorticity has been constructed. This paper adopts a single-equation turbulence KDO (Kinetic Dependent Cnly) model which depends only on the turbulent kinetic energy equation, and introduces a new structure which replaces the old mixing length scale to obtain CKDO model. Then in order to verify its ability to describe compressible free shear turbulence, we select the compressible mixing layer of no wall bondage, large density gradient and strong compressibility effects as an example, whose convective Mach number is 0.8. The results show that KDO model has good control and simulation ability of mixing flow velocity distribution; compared with the original model and other compressible correction models, the velocity distribution, primary Reynolds shear stress and mixing layer thickness obtained with compressible correction model CKDO have a better fit with the experimental value. The results illustrate that the new mixing length has a good ability of characterization for compressible free shear turbulent mixing layer.