  The present study assesses the performance of the Wall Adapting SGS models
along with the Dynamic Smagorinsky model for flows involving separation,
reattachment and swirl. Due to the simple geometry and wide application in a
variety of engineering systems, the Backward-Facing Step (BFS) geometry and
Confined Swirling Flow (CSF) geometry are invoked in the present case. The
calculation of the SGS stresses employs three models, namely, the Dynamic
Smagorinsky model, the Wall Adapting Local Eddy viscosity (WALE) model and the
Dynamic WALE model. For studying the effect of the grid sensitivity, the
simulations are performed over two sets of grids with different resolutions
based on the non-dimensional wall distance parameter ( y+ ). Grids
corresponding to y+ = 70 and y+ = 20 are employed for the subsonic flow over
the BFS while grids corresponding to y+ = 40 and y+ = 20 are employed for
supersonic flow over the BFS and for confined swirling flow geometry. The
validation against the experimental results includes the mean flow fields and
the turbulent stresses obtained for each case. The results reveal that for the
fine grid (y+ = 20), the near wall eddy viscosity profile for the WALE model is
better than both the Dynamic WALE and the Dynamic Smagorinsky model. The
difference between the predictions of the coarse and fine grids for Dynamic
Smagorinsky and the WALE model is high whereas, the Dynamic WALE model is
almost insensitive to the grid resolutions considered for the present case. The
mean velocity and pressure values as well as the turbulent quantities predicted
by the Dynamic WALE model are closest to the experimental values for all the
cases.
