Multi-scale modelling of polydisperse cloud cavitation

Cavitation occurs in a wide range of flows, from rotating machinery to biomedical applications.

In most engineering applications, it constitutes a nuisance, as e.g. material damage or noise, and puts design constraints that limits the performance.

In other applications the same mechanisms are wanted, e.g., to degrade substances in waste water treatment processes or break kidney stones in medicine.

In all cases, improved predictive simulation tools are needed to favourably control the development of the vapor bubble cloud and to better understand the underlying mechanisms of the flow evolution.To meet this, we will here develop a simulation model that can provide significantly improved accuracy for complex cloud cavitation dynamics at a reasonable computational cost.

The key to the improvement lies in better consideration of the bubble sizes in the clouds to be incorporated in realizable physics models and a mathematically robust coupling algorithm across all scales.

A Population Balance Equation (PBE) model will be developed to account for the bubble size distribution on large and intermediate scales.

The PBE approach will be coupled to a Lagrangian model, where subgrid bubble swarms will be transported, in order to represent the small scale in the problems. A robust and grid independent coupling method will be developed.

Finally, the behaviour of the bubble swarms will be studied using DNS in order to ensure correct transport in the Lagrangian model.