Flow transition and fluid forces reduction for flow around two tandem cylinders

Abstract

The numerical study of two-dimensional flow in a channel past two tandem rectangular cylinders is performed using the lattice Boltzmann method (LBM). Investigations are performed for different aspect ratios (AR) and gap spacings (g) values at Reynolds number (Re = 100). We selected four aspect ratios and ten gap spacing values. These parameters attribute five different flow behaviors. The flow transitions and sensitivity of the fluid forces are analyzed with the help of vorticity contours visualization, streamlines visualization, time trace analysis of forces, power spectra of lift forces, and integral parameters. The outcomes of these investigations yield that both parameters are very effective for the transition of the flow regime. It is examined that drag force is a decreasing function of AR, and a 65% reduction is found on the upstream cylinder in a square case. The g = 4 is the critical gap spacing for AR = 1. The mean values of forces exhibit nearly constant behavior for large gap spacing for any fixed AR. Secondary vortex shading frequency is also seen when the flow is interactive.

Keywords

• Numerical simulations
• Lattice Boltzmann method
• Wake structure mechanism
• Fluid forces
• Flow transitions
• Aspect ratio