CFD Simulations of Scour From the Flow Induced By a Rotating Wheel

Scour is a kind of erosion induced by a fluid flow on a collection of solid particles. The Wheel Erosion Test (WET) experimental setup (Ndoye et al. in Scour and Erosion—Proceedings of the 8th international conference on scour and erosion, ICSE, CRS Press, Balkema, 1011–1017 [1]; Kotelon et al. in Caractérisation de l’érodabilité des sols cohésifs et des sédiments naturel. Private Communication [2]) was developed to monitor scour in a controlled environment. Within a water tank, a wheel rotates counterclockwise above an initially flat sediment bed. This motion sets the surrounding fluid in motion, causing it to transport sediments away from the wheel and create a depression underneath it. In this study, we use the neptune_cfd code, based on the Eulerian n-fluid modeling approach, to simulate numerically scour resulting from the flow generated by a rotating wheel. Our simulation results are compared with experimental measurements obtained with an acoustic method (Kotelon et al. in Caractérisation de l’érodabilité des sols cohésifs et des sédiments naturel. Private Communication [2]). These experiments encompass different combinations of wheel rotation velocity and wheel-to-bed distance which are reproduced numerically. The rotation of the wheel is modeled by imposing a tangential velocity at the wheel wall. We successfully reproduced the time evolution of the overall shape of the scour hole in the initial stage. The final equilibrium scour depth obtained is smaller and is reached sooner than reported in the experiments. Some hypotheses are formulated to explain this trend. Then, we observed an increase in scour depth when i) the wheel's rotation speed is increased and ii) the wheel-to-bed distance is decreased, consistent with experimental data.