Numerical studies of two side-by-side elastic cylinders in a cross-flow

Flow-induced vibrations of two side-by-side circular cylinders in a cross-f low at different spacing ratios and mass-damping parameters are examined nu merically. The two cylinders are simply supported at both ends. Two differe nt cases are considered: one is the rigid case where the structural stiffne ss of the cylinder is assumed to be infinite, and the other is the elastic case where the cylinders undergo oscillations. In the latter case, the cyli nders vibrate under the action of the unsteady flow-induced forces. Both ca ses are simulated at a Reynolds number of 200, which represents a typical l aminar flow. The present approach solves the unsteady now field using a fin ite element method with a deforming grid to accommodate the moving cylinder s. As for the cylinder motions, a two-degree-of-freedom structural dynamics model is invoked. Fluid-structure interactions are resolved through iterat ion at the same time step. Numerical calculations of the rigid case are val idated against previously published results. Good agreement is obtained bet ween the present calculations and the data. The calculated visualization is compared with its experimental counterpart and the flow patterns are found to be consistent with experimental observation. Finally, the flow behind t he vibrating cylinders is analysed with an objective to understand the effe ct of cylinder motions on the near wake. The calculated flow patterns at di fferent spacing ratios are found to be consistent with previously documente d experimental observations. (C) 2001 Academic Press.