Low Reynolds number channelized fluid flow of asymmetric plane to a non-asymmetric plane with a sudden expansion by using lattice Boltzmann method

The transition of viscous fluid flow around the square cylinder placed in a computational domain with a sudden expansion at low Reynolds numbers (Re) is investigated numerically by using the lattice Boltzmann method. The flow analysis is based on various Reynolds numbers and expansion ratios of the channel for different gap spacing ratios (g*), and both the Re and gap spacing ratios are studied for g* = 1, 5, and 10 and Re = 75, 100, 125, and 150, respectively. Here, g* = g/D, where g is the expansion ratio of the flow and D is the diameter of the cylinder. From the flow phenomena, we observed that the flow remains symmetric to a certain level depending on low Reynolds numbers. Hydrodynamic forces of the cylinder are strongly based on the expansion ratios. The effect of various Reynolds numbers and gap spacing ratios on the lift forces and drag coefficient is also analyzed. The bifurcation phenomena of asymmetric to nonasymmetric states occur with the increase in Reynolds numbers and expansion and spacing ratios.