Numerical study of the bubble wake characteristics for underwater vehicles based on multiscale Euler–Euler method

The bubble wake for underwater vehicles involves a complex system for two-phase gas–liquid flow and the bubble sizes exhibit multi-scale variations. The gas–liquid interactions are complex and bubble sizes exhibit multi-scale variations due to bubble coalescence and breakup. Current research on the characteristics of this bubble wake remains limited. In this paper, the Euler–Euler two-phase flow approach combined with the multiple size group methodology based on the OpenFOAM framework is established. Following the efficient validation of the numerical model, the bubble wakes produced by gas exhaust on an underwater vehicle are examined. The effects of air exhaust position, water speeds, and air flow rates on bubble wakes are discussed. The results indicate that the bubble wake forms the gas band with gradually increasing thickness. The distribution of bubble size on the body surface appears to be relatively concentrated in small sizes, and behind the body, the bubble size increases and its distribution becomes more dispersed, which is due to different turbulence effects. The wake produced on the top exhaust diffuses more easily. Bubble sizes of the bottom and top exhausts are larger than those of the side exhaust. Higher water speeds and lower gas flow rates can produce more concentrated, smaller bubbles. For the body surface, the bubble size distribution is significantly more sensitive to changes in water speeds than to variations in air flow rates. Behind the body, the influence of water speeds on the distribution of bubble size is similar to that at different air flow rates.