A novel approach to reduce the computation time for CFD; hybrid LES–RANS modelling on parallel computers

Large Eddy Simulation is a method of obtaining high accuracy computational results for modelling fluid flow. Unfortunately it is computationally expensive limiting it to users of large parallel machines. However, it may be that the use of LES leads to an over-resolution of the problem because the bu...

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Bibliographic Details
Main Author: Turnbull, Julian
Other Authors: Thompson, Chris
Format: Others
Language:en_UK
Published: Cranfield University 2005
Subjects:
Online Access:http://hdl.handle.net/1826/104
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spelling ndltd-CRANFIELD1-oai-dspace.lib.cranfield.ac.uk-1826-1042013-04-19T15:25:07ZA novel approach to reduce the computation time for CFD; hybrid LES–RANS modelling on parallel computersTurnbull, JulianParallel computingTurbulenceLarge Eddy SimulationSmagorinsky modelLarge Eddy Simulation is a method of obtaining high accuracy computational results for modelling fluid flow. Unfortunately it is computationally expensive limiting it to users of large parallel machines. However, it may be that the use of LES leads to an over-resolution of the problem because the bulk of the computational domain could be adequately modelled using the Reynolds averaged approach. A study has been undertaken to assess the feasibility, both in accuracy and computational efficiency of using a parallel computer to solve both LES and RANS type turbulence models on the same domain for the problem flow over a circular cylinder at Reynolds number 3 900 To do this the domain has been created and then divided into two sub-domains, one for the LES model and one for the kappa - epsilon turbulence model. The hybrid model has been developed specifically for a parallel computing environment and the user is able to allocate modelling techniques to processors in a way which enables expansion of the model to any number of processors. Computational experimentation has shown that the combination of the Smagorinsky model can be used to capture the vortex shedding from the cylinder and the information successfully passed to the kappa - epsilon model for the dissipation of the vortices further downstream. The results have been compared to high accuracy LES results and with both kappa - epsilon and Smagorinsky LES computations on the same domain. The hybrid models developed compare well with the Smagorinsky model capturing the vortex shedding with the correct periodicity. Suggestions for future work have been made to develop this idea further, and to investigate the possibility of using the technology for the modelling of mixing and fast chemical reactions based on the more accurate prediction of the turbulence levels in the LES sub-domain.Cranfield UniversitySchool of EngineeringThompson, Chris2005-11-23T14:32:53Z2005-11-23T14:32:53Z2003Thesis or dissertationDoctoralPhD1883 bytes5281283 bytestext/plainapplication/pdfhttp://hdl.handle.net/1826/104en_UK
collection NDLTD
language en_UK
format Others
sources NDLTD
topic Parallel computing
Turbulence
Large Eddy Simulation
Smagorinsky model
spellingShingle Parallel computing
Turbulence
Large Eddy Simulation
Smagorinsky model
Turnbull, Julian
A novel approach to reduce the computation time for CFD; hybrid LES–RANS modelling on parallel computers
description Large Eddy Simulation is a method of obtaining high accuracy computational results for modelling fluid flow. Unfortunately it is computationally expensive limiting it to users of large parallel machines. However, it may be that the use of LES leads to an over-resolution of the problem because the bulk of the computational domain could be adequately modelled using the Reynolds averaged approach. A study has been undertaken to assess the feasibility, both in accuracy and computational efficiency of using a parallel computer to solve both LES and RANS type turbulence models on the same domain for the problem flow over a circular cylinder at Reynolds number 3 900 To do this the domain has been created and then divided into two sub-domains, one for the LES model and one for the kappa - epsilon turbulence model. The hybrid model has been developed specifically for a parallel computing environment and the user is able to allocate modelling techniques to processors in a way which enables expansion of the model to any number of processors. Computational experimentation has shown that the combination of the Smagorinsky model can be used to capture the vortex shedding from the cylinder and the information successfully passed to the kappa - epsilon model for the dissipation of the vortices further downstream. The results have been compared to high accuracy LES results and with both kappa - epsilon and Smagorinsky LES computations on the same domain. The hybrid models developed compare well with the Smagorinsky model capturing the vortex shedding with the correct periodicity. Suggestions for future work have been made to develop this idea further, and to investigate the possibility of using the technology for the modelling of mixing and fast chemical reactions based on the more accurate prediction of the turbulence levels in the LES sub-domain.
author2 Thompson, Chris
author_facet Thompson, Chris
Turnbull, Julian
author Turnbull, Julian
author_sort Turnbull, Julian
title A novel approach to reduce the computation time for CFD; hybrid LES–RANS modelling on parallel computers
title_short A novel approach to reduce the computation time for CFD; hybrid LES–RANS modelling on parallel computers
title_full A novel approach to reduce the computation time for CFD; hybrid LES–RANS modelling on parallel computers
title_fullStr A novel approach to reduce the computation time for CFD; hybrid LES–RANS modelling on parallel computers
title_full_unstemmed A novel approach to reduce the computation time for CFD; hybrid LES–RANS modelling on parallel computers
title_sort novel approach to reduce the computation time for cfd; hybrid les–rans modelling on parallel computers
publisher Cranfield University
publishDate 2005
url http://hdl.handle.net/1826/104
work_keys_str_mv AT turnbulljulian anovelapproachtoreducethecomputationtimeforcfdhybridlesransmodellingonparallelcomputers
AT turnbulljulian novelapproachtoreducethecomputationtimeforcfdhybridlesransmodellingonparallelcomputers
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