EXPERIMENTAL-EVIDENCE OF DISCRETE STROUHAL NUMBERS FOR THE FLOW PAST A SPHERE IN A CONFINED GEOMETRY

Abstract

An experiment to study the motion of a sphere moving along a circular cylinder filled with water is reported. The motion shows a periodic behavior when the Reynolds number exceeds the value for which the trailing ring-eddy structure becomes unstable. The oscillatory motion becomes more apparent when the diameters of the sphere and the cylinder are of the same order. It is found that the Strouhal number seems to take discrete values, supporting a universal behavior proposed by Levi.