Application of a one-fluid model for large scale homogeneous unsteady cavitation: The modified Schmidt model

It is found that the one-fluid cavitation model developed by Schmidt et al. [Schmidt DP, Rutland CJ, Corradini ML. A fully compressible, two-dimensional model of small, high speed, cavitating nozzles. Atomiz Sprays 1999;9:255–76] (Schmidt Model) does not work consistently when applied to simulate the unsteady transient cavitating flows with a large vapor to liquid density ratio or under the condition of a low surrounding pressure. In this work, the apparent difficulties of the Schmidt model are analyzed and a modified Schmidt model is proposed for greater robustness and consistency. The modified Schmidt model is then applied to study the creation, evolution and collapse of transient cavitation commonly observed in underwater explosions and industrial pipe flow. The model is firstly verified by simulating several cavitating flows where analytical, experimental or numerical results are available for comparison, and then applied to multi-dimensional transient cavitating flows generated by underwater explosions. The numerical results show that the modified Schmidt model can overcome the difficulties associated with the (original) Schmidt model and be applied to both small and large scale transient cavitating flows to predict the pressure surge caused by cavitation collapse regardless of the surrounding pressure.