Oscillations of the gas-liquid interface during the inverse Leidenfrost phenomenon

Abstract

In this study, the water entry of a high-temperature sphere was experimentally investigated to explore the dynamics of the inverse Leidenfrost phenomenon. During this process, oscillations were observed on the gas-liquid interface, which originated at the sphere's windward surface and propagated upward. To capture flow details that could not be obtained experimentally, a numerical model was developed by solving the complete formation of the governing equations. The numerical results matched well with the experimental data and revealed that the oscillations resulted from the collective coupling among fluid flow, heat transfer, and phase change. To further reveal the physical mechanism of these oscillations, a reduced-order theoretical model was established by employing the potential flow assumption and the Karman-Pohlhausen method. Based on mass and momentum conservation, an expression for the oscillation period of the gas-liquid interface was derived from this model. The theoretical predictions showed excellent agreement with both experimental and numerical results, validating the proposed model.