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=1.25L/B=1.25 and b/B=0.5b/B=0.5 gives rise to maximum amplitude of vibration with (a/B)max=0.57(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.