Numerical simulation of flows past multiple cylinders using the hybrid Local Domain Free Discretization and Immersed Boundary Method

Study of the flow around a group of cylinders (such as risers of the offshore platforms) has been the challenging subject because of its inherent complexity. The research on this problem is important because flow interference between cylinders is responsible for some significant changes in the characteristics of fluid loads. In this paper, the hybrid Local Domain-Free Discretization-Immersed Boundary Method (LDFD-IBM), which combines the strengths of LDFD method and Immersed Boundary Method (IBM), is adopted to solve this problem. The advantages of the LDFD-IBM over conventional IBM are its truly second-order accuracy and simple implementation using a regular fixed Cartesian mesh. In the present investigation, the solver has been applied to simulate the unsteady viscous flow past two cylinders and three cylinders at different configurations in a uniform cross flow. The streamlines and vorticity contours are plotted for the flow visualization. The lift and drag coefficients time histories are presented.