Modelling and simulation of the formation of single phase and compound fluid volumes

• Main Author: Simmons, Jonathan Adnrew
• Published: University of Birmingham 2015
• Subjects: 510; QA Mathematics
• Online Access: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.665785

In this thesis the formation of single phase and compound fluid volumes is investigated and simulated numerically. The continuum fluid mechanical models that describe the generation of a gas bubble from an orifice as well as the topologically inverse process of the formation of a single or compound liquid drop from a nozzle are complex, involving a time dependent flow domain and the non-linear dynamics of the fluid, so that to find a solution to the corresponding problem a numerical method is required. A computational framework based on the finite element method is therefore constructed to simulate these processes. In each study, the simulations are compared to available experimental results and the relevant parameter space is investigated in order to describe the influence that each parameter has on the process. The work on bubble formation is split into two cases. In the first case, where the three phase solid-liquid-gas contact line remains pinned to the rim of the orifice, it is seen that the scaling laws that are used to describe the volume of a bubble are ineffectual over the range of flow rates considered. In the second and more complicated case, where the contact line is free to move along the solid surface, a model that allows the contact angle to behave dynamically and vary from its static value is required to accurately describe experiments. The work on liquid drops mainly focuses on the generation of a compound drop, which is extremely sensitive to changes in parameters, rather than a single drop, which is considered only as a test case.