Direct numerical simulation on local scour around the cylinder induced by internal solitary waves propagating over a slope

Publication Summary

Direct numerical simulation is employed with the immersed boundary method to study how the ISWs create local scour around the cylinder. Numerical results show that the geometrical morphology of the local scour depends on the relative location of the cylinder to the breaking point of the ISWs. It is concluded from the results that the erosion mainly occurs when the ISWs shoal on a slope. In addition, when the ISWs begin to break, the shear stress induced by the ISWs reduces and tends to fail to erode the bed, so in all cases the local scours are backfilled to some extent after the ISWs breaking. If the cylinder is near the breaking point, a vertical upward flow is induced near the cylinder that can bring the suspended sediment to the pycnocline when the ISWs shoal. As a result, the suspended sediment concentration at the bottom is small. On the other hand, if the cylinder is away from the breaking point without the vertical upward flow, the backfill is in a great quantity due to the fact that deposition will occur on the condition that the suspended sediment concentration is high at the bottom. • 3D-DNS with improved IBM is employed. • The erosion mainly occurs when the ISWs shoal. • The local scour may backfill.