Abstract: To assess a modified RNG κ-ε turbulence model, the cloud cavitating flow around a Clark-y hydrofoil is investigated using RNG κ-ε turbulence model with a modified turbulence viscosity coefficient, and the coefficient is related to the vapor and liquid densities in the cavitating region. The time evolutions of the shape of cloud cavities, the lift and drag force around the hydrofoil have been obtained, and compared with experimental results. It is shown that the modified model can predict successfully the characteristics of cavitation and the detailed process of the cavitation shedding. Values of n in the modified coefficient are found to have a strong influence on the cavity length, the vapor volume, the lift and drag force, but no significant effect on the frequency distribution of the dynamics around the foil is observed.