Numerical study on resistance characteristics of flow around two cylinders

Lattice Boltzmann models (LBM) is a recently developed method in computational fluid dynamics, and it is particularly suitable for flow modeling in complex boundary area. In this paper, the resistance characteristics of gas flow around two cylinders are numerically studied using LBM. The drag force and drag coefficient of each cylinder are studied by varying the cylinder distance, Reynold number, and the attack angle. Three typical scenarios are studies: The first scenario is to calculate 10 typical cases with the cylinder distance varying from 1.2d to 3.0d where the Reynolds number is fixed to be 20. The calculated results show that the smallest stress acting on the downstream cylinder exists when the cylinder distance is between 1.2d and 1.4d. Furthermore, the minimum total drag force acting on the two cylinders occurs when cylinder distance is 1.6d We also found that the downstream cylinder has no impact on resistance coefficient of upstream cylinder when the cylinder distance is greater than 2d. The second scenario is to study the effects of Reynolds number on the resistance characteristics of the two cylinders by fixing the cylinder distance as 1.2d. Results show that the weakest stress on the secondary cylinder in tandem arrangement exists at a point where the Reynolds number is between 30 and 40. The results in the third scenario show that the attack angle has great effect on the resistance coefficient of each cylinder. These reasonable results can server as the scientific foundation for further research and implementation of flow over multi-cylinders under low Reynold numbers.