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Dynamic refinement and boundary contact forces in smoothed particle hydrodynamics with applications in fluid flow problems. / Jonathan Feldman

Swansea University Author: Jonathan Feldman

Abstract

Smoothed Particle Hydrodynamics (SPH) is a relatively new, simple and effective numerical method that can be used to solve a variety of difficult problems in computational mechanics. It is a fully Lagrangian meshless method ideal for solving large deformation problems such as complex free surface fl...

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Published: 2006
Institution: Swansea University
Degree level: Doctoral
Degree name: Ph.D
URI: https://cronfa.swan.ac.uk/Record/cronfa42459
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first_indexed 2018-08-02T18:54:45Z
last_indexed 2018-08-03T10:10:12Z
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spelling 2018-08-02T16:24:29.3221945 v2 42459 2018-08-02 Dynamic refinement and boundary contact forces in smoothed particle hydrodynamics with applications in fluid flow problems. 0ef170c4d977dd500ad266f89ffd4d9b NULL Jonathan Feldman Jonathan Feldman true true 2018-08-02 Smoothed Particle Hydrodynamics (SPH) is a relatively new, simple and effective numerical method that can be used to solve a variety of difficult problems in computational mechanics. It is a fully Lagrangian meshless method ideal for solving large deformation problems such as complex free surface fluid flows. This research was carried out with the support of BAE Systems and falls into two distinct areas. Firstly to investigate new methods for treating fixed boundaries and secondly to investigate refinement algorithms which allow for both sparsely and densely populated regions of particles within the same computational domain. Much work has been done in the modelling of particle-boundary interactions in SPH since the governing equations do not naturally incorporate essential boundary conditions. In this research a new technique for calculating boundary contact forces is developed. The forces are obtained from a variational principle and as such conserve both the linear and angular momentum of the system. The boundaries are explicitly defined using this new approach and so the need for additional boundary particles is removed. In the past most SPH derivations have been based on a uniform distribution of particles of equal mass. This leads to large simulations with many particles and long run times. In other mesh based schemes it has become common place to use mesh adaptivity to improve numerical results and reduce computation times. With a corresponding refinement strategy SPH can gain these same advantages. In this research a refinement strategy based upon particle splitting is developed. Candidate particles are split into several 'daughter' particles according to a given refinement pattern centred about the original particle position. Through the solution of a non-linear minimisation problem the optimal mass distribution for the daughter particles is obtained so as to reduce the errors introduced into the underlying density field. This procedure necessarily conserves the mass of the system. The unique daughter particle velocity configuration that conserves the linear and angular momentum of the system is also identified. The conclusion of the research was the successful implementation of these improvements into the existing SPH framework. As a result the capability and flexibility of the code is greatly increased and the computational expense needed for running large simulations has been reduced. E-Thesis Computational physics.;Fluid mechanics. 31 12 2006 2006-12-31 COLLEGE NANME Engineering COLLEGE CODE Swansea University Doctoral Ph.D 2018-08-02T16:24:29.3221945 2018-08-02T16:24:29.3221945 Faculty of Science and Engineering School of Engineering and Applied Sciences - Uncategorised Jonathan Feldman NULL 1 0042459-02082018162456.pdf 10798167.pdf 2018-08-02T16:24:56.1070000 Output 25281314 application/pdf E-Thesis true 2018-08-02T16:24:56.1070000 false
title Dynamic refinement and boundary contact forces in smoothed particle hydrodynamics with applications in fluid flow problems.
spellingShingle Dynamic refinement and boundary contact forces in smoothed particle hydrodynamics with applications in fluid flow problems.
Jonathan Feldman
title_short Dynamic refinement and boundary contact forces in smoothed particle hydrodynamics with applications in fluid flow problems.
title_full Dynamic refinement and boundary contact forces in smoothed particle hydrodynamics with applications in fluid flow problems.
title_fullStr Dynamic refinement and boundary contact forces in smoothed particle hydrodynamics with applications in fluid flow problems.
title_full_unstemmed Dynamic refinement and boundary contact forces in smoothed particle hydrodynamics with applications in fluid flow problems.
title_sort Dynamic refinement and boundary contact forces in smoothed particle hydrodynamics with applications in fluid flow problems.
author_id_str_mv 0ef170c4d977dd500ad266f89ffd4d9b
author_id_fullname_str_mv 0ef170c4d977dd500ad266f89ffd4d9b_***_Jonathan Feldman
author Jonathan Feldman
author2 Jonathan Feldman
format E-Thesis
publishDate 2006
institution Swansea University
college_str Faculty of Science and Engineering
hierarchytype
hierarchy_top_id facultyofscienceandengineering
hierarchy_top_title Faculty of Science and Engineering
hierarchy_parent_id facultyofscienceandengineering
hierarchy_parent_title Faculty of Science and Engineering
department_str School of Engineering and Applied Sciences - Uncategorised{{{_:::_}}}Faculty of Science and Engineering{{{_:::_}}}School of Engineering and Applied Sciences - Uncategorised
document_store_str 1
active_str 0
description Smoothed Particle Hydrodynamics (SPH) is a relatively new, simple and effective numerical method that can be used to solve a variety of difficult problems in computational mechanics. It is a fully Lagrangian meshless method ideal for solving large deformation problems such as complex free surface fluid flows. This research was carried out with the support of BAE Systems and falls into two distinct areas. Firstly to investigate new methods for treating fixed boundaries and secondly to investigate refinement algorithms which allow for both sparsely and densely populated regions of particles within the same computational domain. Much work has been done in the modelling of particle-boundary interactions in SPH since the governing equations do not naturally incorporate essential boundary conditions. In this research a new technique for calculating boundary contact forces is developed. The forces are obtained from a variational principle and as such conserve both the linear and angular momentum of the system. The boundaries are explicitly defined using this new approach and so the need for additional boundary particles is removed. In the past most SPH derivations have been based on a uniform distribution of particles of equal mass. This leads to large simulations with many particles and long run times. In other mesh based schemes it has become common place to use mesh adaptivity to improve numerical results and reduce computation times. With a corresponding refinement strategy SPH can gain these same advantages. In this research a refinement strategy based upon particle splitting is developed. Candidate particles are split into several 'daughter' particles according to a given refinement pattern centred about the original particle position. Through the solution of a non-linear minimisation problem the optimal mass distribution for the daughter particles is obtained so as to reduce the errors introduced into the underlying density field. This procedure necessarily conserves the mass of the system. The unique daughter particle velocity configuration that conserves the linear and angular momentum of the system is also identified. The conclusion of the research was the successful implementation of these improvements into the existing SPH framework. As a result the capability and flexibility of the code is greatly increased and the computational expense needed for running large simulations has been reduced.
published_date 2006-12-31T03:53:00Z
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score 11.013371

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