Numerical study on domain independency for prediction of vortex shedding parameters of a circular cylinder

Abstract

The catastrophes of history make vortex-induced vibration an extensively studied area. The response predictions of offshore and sub-sea structures have gained importance off-late ever since these have been widely used by the petroleum industry. Most of the studies have confined to the comprehension of wake characteristics and the estimation of hydrodynamic loading and shedding parameters of stationary cylinders. Computational fluid dynamics has evolved as one of the effective tools in prediction of response characteristics under vortex shedding and many researchers have studied various aspects of computations that are crucial with reasonable degree of accuracy. This paper addresses the effect of the geometrical shape of fluid domain that encompasses a marine riser during simulations. Four different shapes are analyzed using Reynolds Averaged Navier–Stokes Equation-based commercial solver, ANSYS®. All four domains have the same number of elements, mesh density, and flow Reynolds number (Re). Hydrodynamic force coefficients and frequency of shedding in each case were estimated and compared with previously published numerical and experimental results. It is observed that circular domain is the most efficient in predicting both loading and shedding characteristics with less than 10% deviation as against the theoretical results. Elliptical and square domains failed to capture the vortex shedding phenomenon. The study reveals a significant characteristic of numerical simulations on the modeling and meshing of both near-wall and wake regions.