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-flow at different spacing ratios and mass-damping parameters are examined numerically. The two cylinders are simply supported at both ends. Two different cases are considered: one is the rigid case where the structural stiffness 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 cylinders vibrate under the action of the unsteady flow-induced forces. Both cases are simulated at a Reynolds number of 200, which represents a typical laminar flow. The present approach solves the unsteady now field using a finite element method with a deforming grid to accommodate the moving cylinders. As for the cylinder motions, a two-degree-of-freedom structural dynamics model is invoked. Fluid-structure interactions are resolved through iteration at the same time step. Numerical calculations of the rigid case are validated against previously published results. Good agreement is obtained between 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 the vibrating cylinders is analysed with an objective to understand the effect of cylinder motions on the near wake. The calculated flow patterns at different spacing ratios are found to be consistent with previously documented experimental observations. (C) 2001 Academic Press.