A numerical investigation of flow past helically discrete straked (HDS) cylinder at sub-critical Re

Almost every components in the offshore structures are cylindrical members which can be rigid or flexible. These structures experience huge unsteady vortex-induced forces due to the current loads resulting in fatigue failure. Passive and active flow control devices are usually employed to reduce the forces acting on the bluff body. The prime aspect of this study is to examine the performance of strakes to access the vortex-induced loads suppression on a circular cylinder. The different configurations of strakes arrangements presented in this paper are conventional continuous helical strakes (HS) and helical discrete strakes (HDS). The investigations are carried out using a commercially available CFD solver called STAR-CCM+ by employing Reynolds-Averaged Naiver-Stokes method (RANS) and implementing SST k - ω turbulence model. The drag and lift force coefficients of cylinder with strakes are compared to bare cylinder (BC) at Re=5000. From our studies it is observed that the cylinder with helically discrete strakes helps in suppressing vortex shedding process and reduce drag by 20% with respect to the cylinder with conventional helical strakes.