Yury Egorov

A Scale-Adaptive Simulation Model using Two-Equation Models

The Scale-Adaptive Simulation (SAS) concept is based on the introduction of the von Karman length-scale into the turbulence scale equation. The information provided by the von Karman length-scale allows SAS models to dynamically adjust to resolved structures in a URANS simulation, which results in a LES-like behavior in unsteady regions of the flowfield. At the same time, the model provides standard RANS capabilities in stable flow regions. The introduction of the von Karman length-scale is based on the reformulation of Rottas’s equation for the integral length-scale. In the current paper, the term containing the von Karman length-scale is transformed to the SST turbulence model. It allows the SST model to be operated in a SAS mode.

CFD Simulations of the Aeroacoustic Noise Generated by a Cavity Flow

CFD simulations of the flow inside a cavity with a length to depth ratio (L/D) of 5 and a width to depth ratio (W/D) of 1 were performed using the 3D CFX code with the newly developed SAS (Scale Adaptive Simulation) turbulence model. The free-stream flow has a zero incidence and a Reynolds number of 1×106 (based on the cavity length). Two meshes were used with similar sizes and having different node distribution along the cavity regions. The former grid uses a constant step mesh along the cavity and the latter uses a stepwise mesh, which resolves much finer the shear layer at the start of the cavity. Predicted noise spectra at 10 monitor points, overall sound and Rossiter modes were compared to the experimental data. To complete this study, the effect of the sampling time was assessed. In general, the agreement between the compared results was very satisfactory showing the ability of the SAS model to predict both narrowband and broadband noise.© 2006 ASME