High performance unsteady projection methods for incompressible turbulent flows /
In this research work, three major challenges of numerically simulating turbulent incompressible flows are investigated, namely; the pressure handling, accurate discretization and parallel processing for speeding up calculations. A high performance, unsteady, generalized coordinates solver has been...
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| Main Author: | |
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| Format: | Thesis |
| Language: | English |
| Published: |
Kuala Lumpur :
International Islamic University Malaysia,
2015
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| Subjects: | |
| Online Access: | http://studentrepo.iium.edu.my/handle/123456789/4856 |
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| Summary: | In this research work, three major challenges of numerically simulating turbulent incompressible flows are investigated, namely; the pressure handling, accurate discretization and parallel processing for speeding up calculations. A high performance, unsteady, generalized coordinates solver has been developed based on the finite difference method for this investigation. The solver focuses on accurate calculation of the pressure field and handling of turbulent flows. The pressure handling part consists of Projection Method and Semi-Implicit Method for Pressure-Linked Equations (SIMPLE) algorithm while for the turbulence calculations, a standard k-ε turbulence model and the Hoda's k-τ model are implemented. It also provides several options for comparing different types of discretization for the convective and diffusive terms. The solver utilizes MPI (Message Passing Interfaces) to achieve parallel processing and to speed up the simulations. A number of benchmark cases are simulated and compared with available experimental and numerical results from literature. For the pressure handling part, comparisons between explicit Projection Method and implicit SIMPLE algorithm have been performed. Explicit Projection Method gains advantages compared to SIMPLE algorithm in its accuracy and speed. Also, a higher-order pressure-correction Projection Method has been implemented and tested. Results shown that the higher-order schemes is more accurate but unstable and an effort have been made to identify the sources of instability. The main issues related to discretization that are addressed in this work are the upwinding of the convective term and the formulations of the diffusive term. The influence of different orders of upwinding scheme and the handling of the stresses in the diffusive terms on the accuracy of the results have been investigated. The solver has also been applied to turbulent flows and it was found that in incompressible flow, the Hoda's k-τ model shows better results in the region close to solid surfaces. In conclusion, an efficient solver capable of handling a wide range of flow scenarios in complex geometries have been developed. |
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| Physical Description: | xvi, 127 leaves : ill. ; 30cm |
| Bibliography: | Includes bibliographical references (leaves 111-117) |