EXPERIMENTAL-STUDY OF SIMILARITY SUBGRID-SCALE MODELS OF TURBULENCE IN THE FAR-FIELD OF A JET

Several versions of similarity subgrid-scale turbulence models are tested a-priori using high Reynolds number experimental data. Measurements are performed by two-dimensional Particle Image Velocimetry (PIV) in the far field of a turbulent round jet. It is first verified that the usual Smagorinsky model is poorly correlated with the real stress tau(ij). On the other hand, a similarity subgrid-scale model based on the 'resolved stress' tenser L(ij), which is obtained by filtering products of resolved velocities at a scale equal to twice the grid scale, displays a much higher level of correlation. Several variants of this model are examined: the mixed model, and the global and local dynamic procedure. Model coefficients are measured, based on the condition that the subgrid models dissipate energy at the correct rate. The experimental data are employed to show that the dynamic procedure [4] yields appropriate model coefficients based only on the resolved portion of the velocity field. Some features of the dynamic procedure in its local formulation are also explored.