Numerical prediction of scouring depth around foundations of offshore structures

Abstract

The pile foundations of offshore structures are vulnerable to local ground loss by scouring. The vortex flow affected by the flow conditions, ground conditions, and the shape of the pile is the main cause of scouring. The decrease of an embedded depth of foundation pile by scouring may lead to an excessive displacement of the structure and a decrease of the bearing power, leading to a collapse of the offshore structure. In this work, a three-dimensional commercial code named STAR-CCM+ has been employed to predict the final depth of the scouring-hole around the foundation of offshore structures. Assuming the bed as a fluid having a high level of dynamic viscosity and density, the prediction has been accomplished by using the multi-phase flow model. The model solves the Reynolds Averaged Navier-Stokes (RANS) equations, and standard k-ε turbulence model to estimate the depth of the scouring-hole. To guarantee the reliability of the model, the results of the numerical model have been compared with available laboratory measurements. A reasonable agreement has been observed.