Hydrodynamics around two identical circular cylinders in tandem arrangements at different flow attack angles

![CDATA[Numerical simulations are conducted to investigate the effects of the flow attacking angles on the hydrodynamic forces on two smooth circular cylinders in a tandem arrangement in a fluid flow. Simulations are conducted at different gap to diameter ratios and a constant Reynolds number (based on the velocity perpendicular to the cylinder) of 500. The three-dimensional incompressible Navier-Stokes equations are solved using Petrov-Galerkin Finite Element Method to simulate the flow. The aim of this study is to investigate the effects of the flow attacking angle on the wake of the circular cylinders for two gap ratios (G/D) of 1 and 3 and its influences on the vortex shedding patterns. G/D = 1 and 3 are chosen because the wake flow at these two gap ratios are in the reattachment and co-shedding regimes, respectively. Very weak three-dimensional (3D) flow appears in the wake of the downstream cylinder at G/D=1. Clear 3D vortices are shed from both upstream and downstream cylinders for all the simulated flow attacking angles and lowered the spanwise coherence behind the downstream cylinder due to the effects of vortex impingement and streamwise vortex structures in the approaching flow.]]