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Title: Numerical simulation of viscoelastic flows
Author: Matallah, H.
Awarding Body: University of Wales Swansea
Current Institution: Swansea University
Date of Award: 1999
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In this thesis, consideration is given to two-dimensional isothermal incompressible flows of rheological complex materials. An introduction is provided on the background rheology and numerical schemes. A time stepping procedure is employed to solve steady state relevant partial differential equations, and in particular the equations of momentum, continuity and the Oldroyd-B constitutive equations. A Petrov Galerkin pressure correction method is used as the base finite element scheme. Model flows, considered as smooth and having analytical solutions are tested for accuracy. In contrast, complex benchmark problems, which may be smooth but with sharp velocity gradients, or alternatively non-smooth, are also solved to test stability and to contrast the quality of results against those in the literature. Despite the considerable effort devoted to establish sophisticated numerical methods to solve highly elastic complex flows of polymeric materials, the simulation of viscoelastic flows through complex geometries remains a challenge. One method that has found favour recently is the elastic-stress-splitting (EVSS) method. There are two features associated with this method, stress-splitting and recovery of velocity gradients. In this thesis, recovery and stress-splitting schemes for plane and axi-symmetric flows of non-Newtonian fluids are presented. Accuracy, stability and numerical performance issues are addressed for different schemes. It is established that recovery-based schemes are stable and superior in higher Deborah number attenuation over conventional and EVSS alternatives. Hence, it is shown that it is the recovery aspect that is responsible for improved stability behaviour. In this context, a 4:1 plane contraction and the flow past a cylinder in an infinite domain are used to analyse vortex activities for Newtonian and viscoelastic flows. Mesh convergence is also analysed.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available