Fluid flow control around unequal cylinder spacing behind three side-by-side cylinders

A numerical study was carried out to systematically investigate the effect of downstream attached splitter plates on the flow around three unequal spacing side-by-side arranged cylinders at the Reynolds number of 150. The lattice Boltzmann method and finite difference successive over-relaxation method are used simultaneously for the solution of the Navier–Stokes equations, in the formulation where the vorticity and the stream function are the field variables. Sixteen different unequal spacing combinations were chosen. The length of the downstream attached splitter plates is 1D, 2D, and 3D. In the case of a flip-flopping flow pattern without splitter plates, more than one peak was found in the power spectra. This study shows that downstream attached splitter plates reduce drag forces. A comparison is made between the cases with and without splitter plates in terms of the time histories of the drag and lift forces, vortex formation mechanisms, and dominant frequencies. The vortex patterns and downstream evolution are also discussed in detail using vorticity contours visualization. Power spectra analysis and fluid forces were presented upon reaching a steady state. Flow characteristics and fluid force coefficients change considerably with the addition of downstream attached splitter plates.