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Title: Development of a hyperbolic equation solver and the improvement of the OpenFOAMR two-phase incompressible flow solver
Author: Omar, Syazana
ISNI:       0000 0004 8500 611X
Awarding Body: Cardiff University
Current Institution: Cardiff University
Date of Award: 2018
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The first part of this thesis proposed new, fully conservative and less oscillatory hyperbolic partial differential equation solvers. Based on the multi-moment method and the Constrained Interpolation Profile Conservative Semi-Lagrangian (CIP-CSL) family of schemes, a new scheme called CIP-CSL3U is introduced to combine with an existing scheme, CIP-CSL3D. Two ENO-like indicators are proposed, which are used to select during runtime a stencil that can efficiently minimise numerical oscillation as well as numerical diffusion. The proposed schemes (CIP-CSL3DU and CIP-CSL3ENO) are validated using various benchmark problems. Discontinuities, as well as smooth solutions, are captured simultaneously with almost no numerical oscillation for nonsmooth solutions. Benchmark tests also show that the results are fourth-order accurate for smooth solutions, and can be applied to compressible and incompressible fluid flow problems. The second part of this work concerns the improvement of the two-phase incompressible flow solver in OpenFOAM. A geometric Level Set method is implemented to couple with a Volume-of-Fluid solver in OpenFOAM. An interface reconstruction algorithm based on cell tetrahedralisation is implemented to work on 2D and 3D unstructured meshes, on serial as well as parallel. The Coupled Level Set Volume-of-Fluid (CLSVOF) solver is validated against scalar transport problems on various mesh types in 2D and 3D. Results indicate a significant improvement over the standard OpenFOAM solver interFoam and some advantAbstract iii age over the newer OpenFOAM solver, interFlow. Mass conservation properties of the VOF method are also retained. The CLSVOF solver is then used to simulate fluid flows with surface tension effects, showing better agreement with experiments and reference solutions compared to standard OpenFOAM solvers. Simulations indicated that CLSVOF could handle complex fluid flows with surface tension dominance as well as with high density ratios. The calculation of curvature using the Level Set field contributed to the improvement in simulations. A simulation of a liquid jet in a gaseous crossflow also showed reasonable agreement with empirical models with some breakup details captured.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available