Question about Nektar++ fiter: Interpolation from field to field for 3DH1D case
******************* This email originates from outside Imperial. Do not click on links and attachments unless you recognise the sender. If you trust the sender, add them to your safe senders list https://spam.ic.ac.uk/SpamConsole/Senders.aspx to disable email stamping for this address. ******************* Dear nektar++ community, I have been using version 5.0.0 of nektar++ to run unsteady incompressible flow simulations of the 3DH1D type, i.e. 2d spectral elements combined with Fourier expansion along one homogeneous direction. The problem I am encountering is interpolation of the resulting field data. I used the nektar++ example file for incompressible Navier Stokes solver ChanFlow_3DH1D_Flowrate_MVM.xml and ran the field interpolation as follows: FieldConvert -m interpfield:fromxml=ChanFlow_3DH1D_Flowrate_MVM.xml:fromfld=ChanFlow_3DH1D_Flowrate_MVM_1.chk \ rect2d.xml interp.chk where rect2d is the file containing the mesh information (Geometry and Expansion) only, the same information copy-pasted from the session .xml file used as input.( When I used the entire session file, same as input file, the module would immediately crash due to segmentation fault.) I received the following error message after the execution of the above: Fatal : Level 0 assertion violation Failed to type cast m_exp[0] terminate called after throwing an instance of 'Nektar::ErrorUtil::NekError' what(): Level 0 assertion violation Failed to type cast m_exp[0] Aborted (core dumped) I have checked the resulting field data specified in ChanFlow_3DH1D_Flowrate_MVM_1.chk , after converting it to .vtu, and it looks to be without obvious faults. I have also had no problems so far interpolating from 2D or 3D cases to the same geometry. Could this be a specific issue about interpolation for the 3DH1D case, or was there an error in the session file or my command execution? I would really appreciate if you could elucidate this matter for me. Best regards, Cheng-Nian Xiao
Dear Cheng-Nian, Thank you for flagging this. I believe that your approach is correct, but the implementation of interpfield was not fully extended to cover 3DH1D cases. In the meantime (while we are working on it), I could suggest an alternative approach which is that of interpolating the meanmode of your 3DH1D case to the new mesh (as a 2D field) and then restarting the new simulation with initial conditions in u,v,p from the interpolated field, and introducing white noise in the w-component: <FUNCTION NAME="InitialConditions"> <F VAR="u,v,p" VALUE="interpolated_field.rst" /> <E VAR="w" VALUE="0.001*awgn(1.0)" /> </FUNCTION> You will then need to make sure you allow long enough before collecting new averages, possibly monitoring the modal energy evolution. I hope this helps. Kind regards, Andrea Cassinelli PhD candidate Department of Aeronautics Imperial College London London SW7 2AZ Mob.: +44 (0)7956957642 On 27 May 2020, at 17:42, Xiao, Chengnian <CHX33@pitt.edu<mailto:CHX33@pitt.edu>> wrote: This email from CHX33@pitt.edu<mailto:CHX33@pitt.edu> originates from outside Imperial. Do not click on links and attachments unless you recognise the sender. If you trust the sender, add them to your safe senders list<https://spam.ic.ac.uk/SpamConsole/Senders.aspx> to disable email stamping for this address. Dear nektar++ community, I have been using version 5.0.0 of nektar++ to run unsteady incompressible flow simulations of the 3DH1D type, i.e. 2d spectral elements combined with Fourier expansion along one homogeneous direction. The problem I am encountering is interpolation of the resulting field data. I used the nektar++ example file for incompressible Navier Stokes solver ChanFlow_3DH1D_Flowrate_MVM.xml and ran the field interpolation as follows: FieldConvert -m interpfield:fromxml=ChanFlow_3DH1D_Flowrate_MVM.xml:fromfld=ChanFlow_3DH1D_Flowrate_MVM_1.chk \ rect2d.xml interp.chk where rect2d is the file containing the mesh information (Geometry and Expansion) only, the same information copy-pasted from the session .xml file used as input.( When I used the entire session file, same as input file, the module would immediately crash due to segmentation fault.) I received the following error message after the execution of the above: Fatal : Level 0 assertion violation Failed to type cast m_exp[0] terminate called after throwing an instance of 'Nektar::ErrorUtil::NekError' what(): Level 0 assertion violation Failed to type cast m_exp[0] Aborted (core dumped) I have checked the resulting field data specified in ChanFlow_3DH1D_Flowrate_MVM_1.chk , after converting it to .vtu, and it looks to be without obvious faults. I have also had no problems so far interpolating from 2D or 3D cases to the same geometry. Could this be a specific issue about interpolation for the 3DH1D case, or was there an error in the session file or my command execution? I would really appreciate if you could elucidate this matter for me. Best regards, Cheng-Nian Xiao _______________________________________________ Nektar-users mailing list Nektar-users@imperial.ac.uk<mailto:Nektar-users@imperial.ac.uk> https://mailman.ic.ac.uk/mailman/listinfo/nektar-users
participants (2)
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Cassinelli, Andrea
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Xiao, Chengnian