In order to reveal the flow shape of scrap tires in energy dissipation and erosion control under sluice, the RNG k-ε turbulence model is applied to simulate the flow where the apron was roughened by scrap tires. The volume of fluid (VOF) method for water air two phase flow is introduced into the tracking of the free surface. The distributions of water, gas volume, velocity and pressure were obtained through simulation. Contrast analyzed, the result is in good agreement with experimental data and shows that the VOF method is feasible for the simulation of roughened flow.