Abstract
A simple modification is proposed to compute free-surface flows with HSMAC type iteration method of computing incompressible flows. It solves for the position of the moving free surface boundary as part of the iteration to satisfy the continuity equation in a non-boundary conforming fixed grid system. It does not need any additional transport equation for tracking the moving boundary as in most methods and a stable and accurate solution can be obtained. The method is verified in a benchmark test case of standing wave and applied to LES computation of a turbulent open-channel flow past a backward-facing step. The results indicate that both instantaneous flow is simulated well and the mean quantities agree with experiment and other methods. It is proved to be a viable method of computing practical free-surface flows
