Smoothed particle hydrodynamics for fluid-solid coupling: modelling fixed and mobile boundaries

Abstract

Smoothed Particle Hydrodynamics (SPH) is a meshless Lagrangian numerical method which has undergone extensive development in recent years. SPH has properties which make it especially suited to certain problem types with which traditional methods have struggled. This includes fluid-solid coupled problems, which are particularly relevant for the modelling of coastal dynamics - a domain which is becoming increasingly relevant owing to the changing global infrastructure and climate. SPH, however, is a relatively young method, and suffers drawbacks which have been dubbed its grand challenges. The main one of interest for this work, is the handling of boundary conditions within the method. This thesis aims to present a discussion on SPH in the context of modelling boundaries, both fixed and mobile. Improvements were made to the so-called semi-analytical boundary method, solving the mathematical and numerical problems associated with the method, and presenting the work in such a way that it can easily beported to existing SPH models. Further discussions and adjustments were also made to the boundary method, attempting to tackle some of its inconsistencies and render it more viable for typical use cases. Finally, the coupling of the DEM method for modelling mobile boundaries was addressed, with a particular focus on mesoscale modelling of solids at a similar resolution to the fluid domain. This was previously an unviable problem, but with improvements to the solid fraction calculation presented here, this is no longer the case. This presents the opportunity for full range mesoscale modelling in SPH.