Comparison of RSM and LES Turbulence Models on Sharp Bend

Recognizing of river flow pattern, deposition and erosion areas in meanders is highly important. Despite the limitations of the physical models in laboratory investigation of flow pattern in meanders, mathematical models can be helpful. In this research, RSM and LES turbulence models have been compared on sharp river bend of a laboratory flume using Fluent Software. The Laboratory flume is a sharp river bend established in hydraulic laboratory of EPFL. In order to investigate turbulence models, depth-averaged parameters were used. Moreover, to quantitatively examine those models, some longitudinal velocity profiles were selected and compared with measured ones. Results of longitudinal depth averaged velocities showed that RSM model is not able to precisely determine the important flow points. This model shows flow separation region within 85 degree and maximum width of 40 percent, though measurements indicated it was located in the region with maximum width of 60 percent of total width and approximately 75 degree. On the contrary, LES model suitably shows separation region. Besides, it better determines maximum measured depth averaged velocity situations rather than RSM model. Investigation of transversal depth-averaged velocity distinguished LES model from RSM as the better model and finally quantitative comparison of velocity profiles showed LES model is more accurate and presents more valid authentic results.