Flow-induced vibration of a square cylinder without and with interference

This paper presents the results of an investigation on the interference effects of a rigid square cylinder on the transverse vibrations of a spring-mounted square cylinder (test cylinder) exposed to a uniform flow. The interference effects were studied for the tandem, side-by-side and staggered arrangements. Experiments have been carried out for various relative dimensions of the test cylinder and the interfering cylinder; the tests for the staggered arrangements were conducted at several tandem distances between the two. The results indicate that there is a critical combination of relative dimensions and spacing that gives rise to maximum amplitude of vibration. Among the cases studied, tandem arrangement with $L/B=1.25$ and $b/B=0.5$ gives rise to maximum amplitude of vibration with $(a/B{)}_{\max }=0.57$. A tentative explanation is offered for the observed features based on flow-visualization studies conducted as a part of the experimental investigation.