Direct-mode interactions in the wake behind a stepped cylinder

Abstract

A computerized flow analysis of wake phenomena caused by a discontinuity in cylinder diameter is presented. The vortex linkage and half-loop formation observed experimentally by Lewis and Gharib [Phys. Fluids A 4, 104 (1992)] have for the first time been reproduced numerically. The instantaneous vorticity and pressure fields provide a distinct picture of the direct-mode interaction, from which it is concluded that a new half-loop is formed every third shedding cycle.