Abstract

Theoretically, the vortex–induced vibration, caused by the trailing vortex shedding in flows around the blunt body, is probably major reason for structural fatigue damage. An effective way in engineering is to attach a thin plate in the wake of the blunt rigid body, that can reduce or suppress such vortex–induced vibration. In this paper, we firstly simulate typical vortex dominant flow problems (e.g. around rigid cylinder flows) by commercial software STAR–CCM+ and the in–house unstructured Navier–Stokes solver. This helps to investigate the mechanism of vortex formation in the wake for typical problems involving the flow around a rigid cylinder. Importantly, the vortexinduced vibration, caused by the trailing vortex shedding in flows around the blunt body, is emphasized by study of flows around a blunt rigid body with a flexible thin plate by the two–way fluid–structure coupling method. Such study on oscillations of a flexible plate in the free stream is necessary, especially for the analysis of the unsteady eddy current wake. For problems with typical vortex dominant flows around rigid cylinder, the Karman vortex street in the wake region of the cylinder is captured, and the results for laminar flows over the rigid cylinder agree well with measurements available by both unstructured Navier–Stokes solvers. We also investigate deformation by numerical simulation of flows around a blunt rigid body with a thin plat. Interestingly, turbulent vortex occurring in fluid–structure interaction is well described for the deformed thin plat by STAR–CCM+. The results can be used to analyze the mechanisms of vortex induced by the rigid or deformed structure and nonlinear free–surface.

INTRODUCTION

A study on unsteady vortex–dominated flows is now more popular in the modern CFD technique, as in this case the particular phenomenon of interest occurs in many areas, for example, the VIV (Vortex Induced Vibration) of a flexible riser. Definitely, the major physical processes involved are very complex, probably subjected to localized steep gradients and nonlinear mechanism. Such study is one of the challenging topics. An elucidation of the more detailed mechanism is essential and always desirable in research and engineering.

This content is only available via PDF.
You can access this article if you purchase or spend a download.