Vortex Dynamics in Near Wake Region Behind a Triangular Cylinder at Intermediate Reynolds Number

Abstract

The vortex dynamics of near wake region of 75 degree triangular cylinder with apex pointing upstream (UP) configuration at Re = 520, 640, 840 and 1040 in the intermediate range is studied numerically in this paper. It was discovered that twin shear layers result in formation of two alternating primary vortices. These primary vortices result in formation of a set of alternating secondary vortices that remain attached to the base of the triangular cylinder at fixed positions irrespective of the Reynolds number. Reynolds number affected only the strengths of secondary vortices. Moreover, it was found that alternating secondary vortices bear a relationship with Reynolds number and vortex shedding frequency. Based on these observations, a statistical relationship between secondary vortex strength and Reynolds Number and an analytical relationship between secondary vortex strength and vortex shedding frequency have been proposed.