The fluid structure interaction (FSI) of free rigid bodies is a hot issue in computational fluid dynamics,and also a common problem in engineering applications. In order to use the iterative force based immersed boundary lattice Boltzmann (IB LB) coupling scheme to simulate FSI problems in which free rigid bodies are involved,the equations of motion were firstly added to the governing equations,then the mathematical model was discretized and solved by the IB LB coupling scheme.Using the sedimentation of two particles as an example,the numerical results of present method and other FSI algorithms were compared.Finally,a challenging problem concerning the fluttering of a rectangular plate in a water tank was addressed in the IB LB framework.The trajectories of the rigid bodies and the flow patterns were in good agreement with the existing experimental results.The comparison of the execution time per time step and the measured averaged velocities with that of existing FSI algorithms showed that this method is computational efficient and accurate in simulating complex FSI problems.
