Thin Film Fluid Flow Simulation on Rotating Discs
Research output: Research › Doctoral Thesis
Prediction and analysis of complex industrial processes, for example wet chemical wafer etching, depend on accurate modelling of physical phenomena. This work presents a series of numerical studies of film flow with an impinging jet on rotating discs which is the basis for a high performance simulation tool that can be used in design and optimisation of such industrial processes. Numerical studies based on the Volume-of-Fluid (VoF) method were performed and evaluated against reported experimental data. The conclusion drawn is that a transient two-phase 3D free-surface VoF-simulation with a dynamically moving jet is impractical for an industrial use due to very long computational times required. The thin film model based on an integral method, which reduces the three-dimensional nature of the problem into a two-dimensional one by integrating the Navier-Stokes equations over the film thickness, is proposed as a possible remedy. An application of Reynolds decomposition and profile modelling of dependent variables allows capturing of the important inertial and centrifugal forces that would otherwise be lost during the equation transformation. An implementation of the derived thin film model was carried out in the open-source software toolbox OpenFOAM using the Finite Area method, a specialisation of the Finite Volume method for film flows on the arbitrary surfaces. The resulting code fulfils the requirements of a high-performance transient incompressible solver for the thin film and features a dynamic inlet implementation. The approach is validated with the ANSYS Fluent software and its VoF-implementation. An extension of the solver with a simple diffusion-controlled chemistry model for a wet chemical etching of silicon wafers is presented.