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