The Performance of RANS Models for Prediction of Flows in Meandering Channels

This research work presents the prediction capability of Reynolds Averaged Navior-Stoke,s equations
based k- & k- turbulence models. Two solvers (SSIIM and FLUENT) were used in this research work. The
performance of the two turbulence models was gauged for one flow case. Mesh dependency check was also done.
Once it was proved that both the models produce approximately same results, the k- model was then tested for its
suitability for studying various flow aspects of meandering channels. Two different meandering channel geometries
with the same sinuosity (centre line planform geometry), main channel meander width/floodplain width ratio and
same main channel aspect ratio were used. However main channel width varied in two cases. Both bankfull and
overbank flows were considered. The bend radius to main channel width ratio (r/bc) of the wider main channel was
1.0 whereas it was 1.8 for narrow channel. The model predicted the depth averaged velocities (DAV), water surface
profiles, velocity vectors in planforms at different levels with good accuracy. It captured all the salient features of
the flow for inbank, low overbank and high overbank flows. From this study it can be concluded that k- model
can be used with confidence in these types of meandering channels.