空泡在固壁附近溃灭的数值模拟

Numerical simulation of the collapse of a bubble near the rigid wall

实验表明,静止流场中的近壁空泡在泡内外压差的驱动下将发生变形收缩,直至完全溃灭消失。在这一过程中,伴随着空泡形状的变化,流场中出现多个高压脉冲和高速射流。本文通过直接求解原始变量的N-S方程,用VOF方法计算气液两相交界面的运动过程,对这一现象进行了数值模拟和分析。结果表明理论分析和实验现象相吻合。

Experiments demonstrated a bubble near a rigid wall in a quiescent fluid field would transform, shrink and finally collapse till disappear due to differential pressures inside and outside of the bubble. With the collapse of the bubble, violent physical changes, such as emission of pressure pulses and high-speed jets and bubble disappearance, would occur. These phenomena were numerically studied by directly solving N-S equations; Youngs' algorithm, one of the VOF methods, was applied to reconstruct and propagate interfaces formed between the bubble and its surrounding fluid. From numerical results, it was found that striking changes of the bubble only happened at the very rear period of the whole process; magnitudes of three major pressure pulses and high-speed jets were remarkably large, which would give a reasonable explaination to bubble corrosion often observed on rigid walls. Numerical and experimental results agreed with each other.