An algorithm for simulating free surface flows is presented using large time step based on the wave-propagation method proposed by LeVeque,and an exact Riemann solver is used.A multiple wave approximation approach was suggested for eliminating the discontinuities found in the rarefaction fans of dam-breaking flows.In addition,we use the random choice method to reduce non-physical oscillations.Applications demonstrate that the algorithm proposed in this paper can considerably increase the CFL number up to 25when modeling dam-break flows,while retaining satisfactory accuracy and efficiency.This suggests that our algorithm has the potential to be applied to modeling free surface flows.
