A preliminary study of fluid-dynamic loads on a plane surface beneath a circular cylinder in the subcritical flow regime

This paper studies the fluctuating forces on a plane surface beneath a circular cylinder in the subcritical flow regime using two-dimensional computational fluid dynamics (cfd) approach. the turbulent flow fields were calculated via numerical solutions of the navier– stokes (n–s) equations without a turbulence model (laminar flow computation),large eddy simulation (les),and reynolds-averaged n-s equations (rans) approach with the shear-stress transport (sst) turbulence model. the primary goal is to evaluate the correctness,accuracy,and applicability of 2-d approximation of turbulence simulation with different approaches for subcritical flow regime (re=5000). some preliminary knowledge of the forces on the plane which is important in studying scours and flow-induced vibration in ocean engineering is obtained. results show that the laminar approach with high mesh resolution can adequately simulate turbulent flows at this moderate reynolds number. specially,the fluctuating forces on the plane surface due to the flow are significant within three times the cylinder diameter in the downstream,and within one cylinder diameter in the upstream of the cylinder. the pressure fluctuations are approximately two orders of magnitude larger than the shear stress fluctuations. in the frequency domain,the fluctuating forces are significant under twice the vortex-shedding frequency. within one cylinder diameter in the downstream and upstream regions of the cylinder,the pressure fluctuations on the plane surface are well correlated whereas the shear stress is not so well correlated. © 2017 aname publication. all rights reserved.