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Title: Numerical simulation of complex flows of non-Newtonian fluids
Author: Baloch, A.
Awarding Body: University College of Swansea
Current Institution: Swansea University
Date of Award: 1994
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A finite element study of incompressible isothermal complex flows of Newtonian and non-Newtonian fluids is presented. The aim of this investigation is to analyse through a numerical technique the non-viscometric flow behaviour of non-Newtonian fluids. The fluid properties are defined utilising various constitutive equations. A semi-implicit Taylor-Galerkin/pressure-correction algorithm is employed to solve Newtonian, generalised inelastic non-Newtonian and fibre suspension flows. A modified Taylor-Galerkin scheme is presented for viscoelastic flows incorporating a consistent streamline upwind Petrov-Galerkin technique for the stress equations. The numerical algorithm is based on a time-marching procedure and a pressure-correction method that introduces multiple solution stages over each time step. The reported results demonstrate the significant influence of inertia on flow development in both converging and diverging flows. Through a study of two and three dimensional flows of Newtonian and viscoelastic fluids through planar expansions it has been possible to draw conclusions concerning the effects of the expansion ratio and the impact of the third spatial dimension. This demonstrates the appearance of lip vortices and subsequently vortex enhancement. Also the influence of the viscoelasticity on flow development is investigated and gives rise to a die-swell effect. Also considered are simulations for viscoelastic planar contraction flows, strain-thickening in extensional flow or abrupt and rounded re-entrant corner axisymmetric circular contractions and fibre suspension planar and axisymmetric circular contraction flows. In particular the influence and interaction between inertia and extensional viscosity are investigated on both flow development and pressure drop that results in transition between lip and salient corner vortices with twin centres and subsequently vortex enhancement. The impact of rigid rod-like fibres is clearly marked on flow structure in both converging and diverging flows.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available