Nuclei activation and bubble population dynamics in cavitation: A comprehensive two-equation model

A comprehensive theory of cavitating flow is developed as the basis for a new approach towards cavitation modelling. The phase change mechanism is governed by the interplay between pressure-driven thermodynamic favourability and cavitation nuclei availability, thus considering the role of free-stream nuclei content. Based on the outcomes of the presented analysis, an Eulerian two-equation model is built. Heterogeneous nucleation from wall nuclei is also incorporated, as well as bubble population dynamics involving breakup and coalescence. Model performance is validated against the cavitating sphere experiments of Brandner et al. (2022), with special emphasis on the differences between nuclei-deplete and nuclei-abundant scenarios. Close agreement with experiments is obtained, accurately predicting the cavity detachment angle in both deplete and abundant conditions. Cavity morphology and unsteady shedding dynamics are captured using Detached Eddy Simulations (DES), highlighting the decisive influence of inceptionsite availability in cavitating flows. The obtained results confirm that free-stream nuclei activation governs the cavitation threshold in nuclei-deplete conditions, providing a numerically robust framework for its quantification.