Flow Around a Rectangular Cylinder with a Section of Various Width/Height Ratios

Abstract

Strouhal number and base pressure of rectangular cylinders with a section of a width/height ratio of 0.8-9 were measured both in wind-tunnels and in a towing tank, in a wide range of Reynolds numbers between 10² and 10⁵.It was found that there exists a certain range of Reynolds numbers where a sudden discontinuity occurs in Strouhal-number curves for rectangular cylinders with the width/height ratio between 1.5 and 3.In addition, we have found an existence of a new critical value of the width/height ratio, i.e., 6, being different from 2.8, at high Reynolds numbers (Re 10⁴).The change of flow pattern corresponding to the discontinuity was confirmed by measurements of velocity profiles and the visualization techniques of a smoke-wire and an aluminum dust methods.