The Frequency of Incipient Vortex-Shedding from a Circular Cylinder in a Laminar Boundary Layer (The Effect of the Gap Ratio on the Vortex Shedding Frequency).

Abstract

The effect of the Reynolds number, the boundary layer thickness and the gap ratio on the beginning of the periodic vortex-shedding from a circular cylinder in a laminar boundary layer was experimentally investigated. The Reynolds number Re, which was defined in terms of the cylinder diameter (d) and the free stream velocity (U0), ranged from 40 to 1000. The range of the boundary layer thickness (d/δ) was from 0.08 to 0.38. The gap ratio defined by the circular cylinder (d) and the clearance between the circular cylinder and the wall (g) was varied from 0.38 to 3.0. As a result, the frequency of the vortex-shedding from the circular cylinder in the laminar boundary layer can be determined by the gap ratio, but it does not depend on the Reynolds number and the boundary layer thickness.