Adaptive Selective frequency damping method for flow past cylinder at Re 100.
Dear all, I have been trying to use Selective frequency damping (SFD) method adopted in the SteadyState Driver, in order to get an unstable steady state solution whose stability is to be determined. I see in the nektar++ user guide there are two approaches: classical one, and the adaptedSFD. I am trying to validate the case of flow past circular cylinder at Re=100 studied by Jordi link herein https://spiral.imperial.ac.uk/bitstream/10044/1/31875/.../Jordi-B-2016-PhD-T... <https://spiral.imperial.ac.uk/bitstream/10044/1/31875/3/Jordi-B-2016-PhD-Thesis.pdf> . With the values of growth rate and frequency mentioned in this thesis, i am able to achieve convergence upto O(-8) for the classical approach. The problem arises when I use AdaptedSFD method. Initially, AdaptedSFD runs smoothly untill tolerance O(-2), then it switches to stability analysis to estimate growth rate and frequency which is used to predict next value of control coefficient and filter width. The problem lies in the estimation of growth rate and frequency which give nonphysical large values of order 10. I have attached the Session.xml, Session_LinNS.xml, and output results generated. Any help is highly appreciated. Cheers Wasim
Hi Wasim, Not entirely sure what to suggest for this one. Can you increase the time scale that you do the stability analysis over to see if that improves the eigenvalue estimate? Cheers, Spencer. On 12 Feb 2019, at 16:25, wasim sarwar <waseemsarwar121@hotmail.com<mailto:waseemsarwar121@hotmail.com>> wrote: Dear all, I have been trying to use Selective frequency damping (SFD) method adopted in the SteadyState Driver, in order to get an unstable steady state solution whose stability is to be determined. I see in the nektar++ user guide there are two approaches: classical one, and the adaptedSFD. I am trying to validate the case of flow past circular cylinder at Re=100 studied by Jordi link herein https://spiral.imperial.ac.uk/bitstream/10044/1/31875/.../Jordi-B-2016-PhD-T... <https://spiral.imperial.ac.uk/bitstream/10044/1/31875/3/Jordi-B-2016-PhD-Thesis.pdf> . With the values of growth rate and frequency mentioned in this thesis, i am able to achieve convergence upto O(-8) for the classical approach. The problem arises when I use AdaptedSFD method. Initially, AdaptedSFD runs smoothly untill tolerance O(-2), then it switches to stability analysis to estimate growth rate and frequency which is used to predict next value of control coefficient and filter width. The problem lies in the estimation of growth rate and frequency which give nonphysical large values of order 10. I have attached the Session.xml, Session_LinNS.xml, and output results generated. Any help is highly appreciated. Cheers Wasim <jFO_P4_2d.out><Session.xml><Session_LinNS.xml>_______________________________________________ Nektar-users mailing list Nektar-users@imperial.ac.uk<mailto:Nektar-users@imperial.ac.uk> https://mailman.ic.ac.uk/mailman/listinfo/nektar-users Spencer Sherwin FREng, FRAeS Head, Aerodynamics, Director of Research Computing Service, Professor of Computational Fluid Mechanics, Department of Aeronautics, s.sherwin@imperial.ac.uk<mailto:s.sherwin@imperial.ac.uk> South Kensington Campus, Phone: +44 (0)20 7594 5052 Imperial College London, Fax: +44 (0)20 7594 1974 London, SW7 2AZ, UK http://www.imperial.ac.uk/people/s.sherwin/
participants (2)
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Sherwin, Spencer J
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wasim sarwar