OpenFOAM Implementation of Microbubble Models for Ocean Applications

An investigation was carried out on the current state of the art in bubble modelling for computational fluid dynamics, and comparisons made between the different methods for both polydisperse and monodisperse multiphase flows. A multigroup method for polydisperse bubbly flows with the bubbles binned in terms of mass was selected from the various alternatives, which included other multigroup models and moment methods. The latter of these involve the integration of moments of the bubble number density function and transport of these quantities. The equations from this multigroup solver were then changed to more accurately and efficiently model cases involving extremely small bubbles over significant amounts of time, as the original model which was subsequently adapted had, as its primary purpose, simulation of larger bubbles over shorter periods of time. This was done by decoupling the gas and liquid momentum equations and adding an empirical rise velocity term for the bubbles. This new model was then partially implemented into OpenFOAM. The functioning of this new solver was confirmed by comparisons between the results and basic analytical solutions to the problems, as well as by means of comparison with another similar multiphase CFD solver (pbeTransportFoam). Following this confirmation of its functionality, the bubble model was implemented into another solver specifically designed for modelling wakes. Finally, the newly created solver was used to run some cases of interest involving a submerged wake.