Combined immersed volume-phase field approach for predicting multiphase fluid structure interactions

Abstract

The application of numerical methods and the development of solution algorithms to solve various multi-physics scenarios are of prime importance in our modern industrialised world. This thesis deals with numerical methods to compute Fluid-Structure Interactions (FSI) oc curring with more than one fluid phase. The underlying discretisation technique used is the versatile finite volume method. The work essentially develops two different components ca pable of accurately handling the multiphase part and the FSI part. It amalgamates them to develop a formulation capable of handling complex multiphase + FSI problems. The problem’s multiphase aspect is taken care of here by developing a binary and a ternary flow phase field formulations based on the modified Cahn-Hilliard equation. The FSI part of the problem is tackled by using the immersed volume approach, which works by employing a permeability penalty term to the momentum equations. The final step is to combine both these techniques, taking the ternary phase field components to compute the interfacial dynamics and using one of the extra phases as the designated solid phase. The permeability penalty term is applied to the solid phase, thus giving us a new numerical algorithm to compute multiphase + FSI problems. A series of validations have been deployed for both the individual models and the combined approach.