Twin Strouhal numbers in pressure loading of circular cylinder at high Reynolds numbers

We present a wind tunnel experiment on a large smooth circular cylinder mounted between walls. The Reynolds number range of interest is [800 000 - 2 170 000]. This low supercritical regime is often encountered in wind engineering applications, especially the excitation of flexible circular structures by vortex shedding. Main measurements are the unsteady wall pressure distributions around the cylinder by means of synchronized pressure taps with high resolution in time and space. By using the bi-orthogonal decom-position of this set of signals, twin Strouhal numbers are detected which correspond to the second and the fourth terms of the decomposition. These terms are found to produce the unsteady lift on the cylinder with a main contribution of the second one for which the associated Strouhal number is close to the one usually found at subcritical Reynolds numbers. (c) 2022 Elsevier Ltd. All rights reserved.

Automated summary

This study presents a wind tunnel experiment on a large smooth circular cylinder mounted between walls. The Reynolds number range of interest is [800 000 - 2 170 000]. By analyzing the unsteady wall pressure distributions, twin Strouhal numbers corresponding to the second and fourth terms of the decomposition are detected. These terms are found to contribute to the unsteady lift on the cylinder, with the second term having the main influence and a Strouhal number similar to those found at subcritical Reynolds numbers.