Numerical simulation of flows about a stationary and a free-falling cylinder using immersed boundary-finite difference lattice boltzmann method

The applicability of the immersed boundary-finite difference lattice Boltzmann method (IB-FDLBM) to high Reynolds number flows about a circular cylinder is examined. Two-dimensional simulations of flows past a stationary circular cylinder are carried out for a wide range of the Reynolds number, Re, i.e., 1 Re 1 10⁵. An immersed boundary-lattice Boltzmann method (IB-LBM) is also used for comparison. Then free-falling circular cylinders are simulated to demonstrate the feasibility of predicting moving particles at high Reynolds numbers. The main conclusions obtained are as follows: (1) steady and unsteady flows about a stationary cylinder are well predicted with IB-LBM and IB-FDLBM, provided that the spatial resolution is high enough to satisfy the conditions of numerical stability, (2) high spatial resolution is required for stable IB-LBM simulation of high Reynolds number flows, (3) IB-FDLBM can stably simulate flows at very high Reynolds numbers without increasing the spatial resolution, (4) IB-FDLBM gives reasonable predictions of the drag coefficient for 1 Re¹10⁵, and (5) IB-FDLBM gives accurate predictions for the motion of free-falling cylinders at intermediate Reynolds numbers.