Turbulence Modeling for Free Shear Flows

It is shown that for theoretical reasons in self-preserving free shear flows governed by the boundary-layer equations there must exist a region, in which the Reynolds stress anisotropies are constant. The theoretical result is confirmed by an analysis of well established experimental data for the plane jet, the axisymmetric jet and the plane mixing layer. The values of the corresponding Reynolds-stress anisotropies are determined, revealing differences between the corresponding eigensystems of these flows. Numerical predictions can be improved by a suitable calibration of the pressure-strain correlation of a Reynolds-stress model.