A multiscale numerical approach which integrates a sub-grid air entrainment model into the two-fluid framework has been proposed to resolve the flowfield created by ventilated cavity including the large-scale cavity profile, gas entrainment at the cavity tail and the bubble dispersion downstream.

We investigated the flow parameter distributions including the void fraction, the bubble velocity and the bubble size distributions in and downstream of the ventilated cavity. Comparisons between the numerical results with the experimental data are in satisfactory agreement, demonstrating the potential of the proposed methodology.

We examined the ventilation rate effect on the cavity shape and the bubbly flow parameters, providing valuable insight on the combined drag reduction mechanism resulted from large-scale cavity and microbubbles.