Understanding how non-condensable gases modify cavitation mass transfer through the van der Waals theory of capillarity

Abstract

Cavitation of a pure fluid continues to be a challenging problem in fluid dynamics. However, most cavitating fluids contain small amounts of non-condensable gases that can change the dynamics of the process significantly. While the effect of non-condensable gases on the surface and bulk properties of the fluid has been studied in detail, its impact on liquid–vapor mass transfer has remained elusive. Here, we provide mechanistic insight into this process using theory and simulations. Our results point to a dual role of non-condensable gases on liquid–vapor mass transfer. While the presence of non-condensable gases always reduces hydrodynamic cavitation, it also leads to a mass transfer mechanism that we call mixing cavitation. We show that mixing cavitation may increase or reduce mass transfer under different physical conditions and can dominate hydrodynamic cavitation. This study opens possibilities to better understand cavitation inception.