CFD-CGDEM coupling model for scour process simulation of submarine pipelines

Abstract

Scour is a key issue affecting the service life of submarine pipelines. Understanding the scour process and scour mechanism around the pipelines is crucial for developing the reasonable and effective scour prevention measures. In this paper, the computational fluid dynamics and coarse-grained discrete element method (CFD-CGDEM) is used to simulate the scour process around the pipeline. The influence of the drag force model which is an important factor for analyzing the scour process of the submarine pipelines is investigated, and the results indicate that the choice of the drag force model has less influence on the simulation results. The characteristic of the CG method is studied considering different CG factors, particle radius and flow velocities. The results show that the CG method which can reduce the large need of computing resources and excessive computation time does not bring large deviation to the results, especially the scour depth beneath the pipelines. The evolution of the scour depth obtained by the CFD-CGDEM model agree well with the experimental results. A reasonable scour phenomenon around the pipeline is shown by the numerical simulation, which implies that the CFD-CGDEM model established in present study can simulate the scour process around the pipelines well.