Mass transfer cavitation model with variable density of nuclei

The performance of the mass transfer cavitation model of Sauer is investigated using a varying nuclei concentration. The Sauer model assumes a uniform nuclei distribution despite measurement of the non-homogeneous nucleus population. Here the nuclei density is studied and a non-homogeneous nuclei distribution in a modified Sauer model is implemented. It is used to study how the increased cavitation nuclei density in regions of low pressure affects the inception of cavitation. The interface between the water and the water vapor is tracked using a volume of fluid method and vaporization and condensation are described by the modified Sauer\ubfs mass transfer model. The nuclei in the liquid phase are modeled with a Lagrangian Particle Tracking method. The LPT computations yield to a non uniform nuclei distribution which consists of nuclei accumulation close to the leading edge and no nuclei on average in the boundary layer of the hydrofoil. The sensitivity of the modified Sauer model to nuclei distribution is proven. The shape of the sheet cavity and the volume of vapour are affected by the nuclei content

Procedure for the break-up of cavitation sheet

The actual mass transfer cavitation models are limited by the grid size dependency of the Volume-Of-Fluid method. A new multi-scale approach is developed which can model the presence of bubbles smaller than the grid size. Using this method for simulations of cavitating hydrofoil will lead to a better modelling of the mixture of vapor and liquid in the transition region between the attached cavity and the shedding cloud. The principle of this approach is to complement the VOF method with a two-way coupling Lagrangian particle tracking method. The VOF-LPT coupling model is tested on simplified configurations for the breakup of an attached cavity. The results show that the model successfully displays the formation of small structures and gives a better description of the liquid/gas mixture

A numerical study of partitioned fluid-structure interaction applied to a cantilever in incompressible turbulent flow

This study presents an approach for partitioned fluid-structure interaction (FSI) applied to large structural deformations, where an incompressible turbulent solver is combined with a structural solver. The implementation is based upon two different open-source libraries by using MPI as a parallel communication protocol, the packages and OpenFOAM. FSI is achieved through a strongly-coupled scheme. The solver has been validated against cases with a submerged cantilever in a channel flow to which experiments, numerical calculations and theoretical solutions are available. The verification of the procedure is performed by using a solid-solid interaction (SSI) study. The solver has proven to be robust and has the same parallel efficiency as the fluid and the solid solver stand-alone