Flow-induced Forces on Two Nearby Spheres

Flow-induced forces on two identical nearby spheres at Re=300 were numerically studied using an immersed boundary method. We consider all possible arrangements of the two spheres in terms of the distance between the spheres and, the angle inclined with respect to the main flow direction. It turns out that significant changes in the characteristics of vortex shedding are noticed depending on how the two spheres are positioned, resulting in quantitative changes of force coefficients on both spheres. Collecting all the numerical results obtained, we present the diagrams for the force coefficients on the distance vs. angle plane for each of the two spheres. The perfect geometrical symmetry implied in the flow configuration allows one to use those diagrams to estimate flow-induced forces on two identical spheres arbitrarily positioned in physical space with respect to the main flow direction.