Abstract: Physically based fluid simulation can provide realism, but simulating water turbulence remains challenging. Recently, there have been much work on gas turbulence, but these algorithms mostly rely on the Kolmogorov theory which is not directly applicable to water turbulence simulation. This paper presents a novel technique for simulating water turbulence. We show that sub-grid turbulence can be created by employing a flow-scale separation technique. We adopted the multi-scale flow separation method to derive a special small-scale equation. Small-scale velocities are then generated and manipulated by the equation. To simulate the turbulence effect, this work employed the vorticity confinement method. By extending the original method to multi-level, we effectively simulate energy cascading effects.