Numerical Study of the Sand Movement around a Cylindrical Body Standing on the Sand

Abstract

The flow around a cylindrical body standing on the sand is computed numerically and the movement of the sand is investigated. The numerical method employed in this study can be divided into three parts:(1)calculation of the flow around the pole using MAC method with a generalized coordinate system;(2)estimation of the sand transfer caused by the flow through the friction;(3) determination of the shape of the ground. Since the computational area changes at step(3), this procedure has to be repeated at each time step. Results show that the horseshoe vortex scoops out the ground in front of the pole. When the pole has the plane perpendicular to the flow, it generates a big horseshoe vortex to make the scouring force strong. On the other hand, when the pole has the cross section that is flat along the flow, such as lens or ellipse, the scouring force becomes weak. Furthermore, it is found that the horseshoe vortex becomes small when the pole has the conical base.