Multi-fluid Modelling Combined with Interface Tracking
Multiphase flow in a pipe can often be characterised by the configuration or flow pattern of the phases involved. Generally, the interaction is the result of the material properties and input parameters of the phases (such as the superficial velocities at the inlets), alongside geometrical constraints (diameter, length, bend radii) of the pipe configuration. The strong coupling of the mechanisms arising in such systems generally governs the physics of the flow dynamics; turbulence, gravity, viscous forces, the coupling between the phases, as well as density and shear-driven instabilities. Phenomena such as interfacial waves, bubble and drop creation, breakup, coalescence, deposition and entrapment directly contribute to the emergence of a wide range of complex flow patterns in multiphase pipe flow.
More generally, accurate prediction of complex flow pattern characteristics via full-scale numerical simulations is challenging due to the interactions of the turbulent gas and liquid phases, which lead to complex interfacial topological transitions. The turbulence present in these systems gives rise to a large range of spatial and temporal scales that require an array of robust and accurate numerical methods to capture the emergent physical phenomena arising particularly in industrially-relevant flows.
This project aims to further develop the multi-component modelling code ‘IC-FERST-Fluidity’ to give a complete parallel framework to accurately model complex multiphase flow in realistic scenarios, such as in pipes and pipe networks. The main methods in the framework that are integral to achieving this are:
(i) compressive advection scheme to ensure the interface between phases are kept sharp, (ii) spatial optimisation of the mesh using highly anisotropic mesh optimisation, (iii) combined finite-element and control-volume methods for the stability of `poor elements', (iv) hydrostatic pressure solver for robustly resolving force balances in a gravitational field, and (v) surface tension for resolving complex interfacial behaviour with coarse mesh resolutions and poor quality elements.
