Large Eddy Simulation of Flow around Twisted Offshore Structure with Drag Reduction and Vortex Suppression

Abstract A twisted cylinder has been newly designed by rotating the elli ptic cross section along the spanwise direction in order to red uce thedrag and vorticies in wake region. The flow around the twisted cylinder at a subcritical Reynolds number (  ) of 3000 is investigatedto analyze the effect of twisted spiral pattern on the drag reduction and vortex suppression using large eddy simulation (LES) . The instantaneous wake structures of the twisted cylinder are compa red with those of a circular and a wavy cylinder at the same  . Theshear layer of the twisted cylinder covering the recirculation region is more elongated than that of the circular and the wavy cylinder. Successively, vortex shedding of the twisted cylinder is consid erably suppressed, compared with those of the circular and the wavy cylinder. Consequently, the mean drag coefficient and the fluct uating lift of the twisted cylinder are less than those of the circular andthe wavy cylinder.Keywords: Twisted cylinder(트위스트 실린더), Large eddy simulation(대형와모사법), Vort ex suppression(와류 감쇠), Drag reduction(저항 저감)