Simulation of microbubble resistance reduction on a suboff model

This paper presents a mixture-model based computational fluid dynamics (CFD) simulation on the two-phase microbubble flow over the hull of a SUBOFF model, aimed at assessing the roles of air-injection-to-freestream velocity ratio and air volume fraction in microbubble resistance reduction. The numerical framework consists of the Reynolds-average Navier-Stokes (RANS) equations and the standard k - ε turbulence model with standard wall function treatment, which is validated, without microbubbles, by existing experimental data of the same SUBOFF model. The effect of velocity ratio is then investigated by comparing different types of the resistance reduction at various water speeds, and the effect of air volume fraction on the friction resistance reduction is also studied with various air injection velocities. This study confirms that both the velocity ratio and air volume fraction play important roles in the microbubble resistance reduction phenomenon.