Dear Vivarelli, Guglielmo A, Thanks for your kind reply. First, perhaps I didn't express myself clearly. In the case where there is already an AverageFields filter, the average field file is not output during the recalculation process, but only after the calculation is finished. Is the final output of this mean field file a continuation result? Second, I have added the AeroForces filiter, the wall is C[16] in the mesh.xml, so I set <PARAM NAME="Boundary">B[16]</PARAM> in AeroForces filiter, but the result of asreforces are all zero. Also I used the <PARAM NAME="Boundary">C[16]</PARAM>, the results are also zero. Am I wrong? With best regards At 2024-12-18 16:03:07, "Vivarelli, Guglielmo A" <guglielmo.vivarelli12@imperial.ac.uk> wrote: Dear Fei Gao, Thank you for your question and interest in using Nektar++, you need to add a "Filter" section at the end of your session file: <FILTERS> <FILTER TYPE="AverageFields"> <PARAM NAME="OutputFile">MyAverageField</PARAM> <PARAM NAME="OutputFrequency">10000</PARAM> <PARAM NAME="SampleFrequency"> 1 </PARAM> </FILTER> <FILTER TYPE="AeroForces"> <PARAM NAME="OutputFile">DragLift</PARAM> <PARAM NAME="OutputFrequency">1</PARAM> <PARAM NAME="Boundary">B[0]</PARAM> </FILTER> </FILTERS> Please see sections "3.5.22 Time-averaged fields" and "3.5.2 Aerodynamic forces", although it says that the "AeroForces" filter does not work with the compressible solver I got it to work with the above. I hope this answers your query. Thanks, Guglielmo From: nektar-users-bounces@imperial.ac.uk <nektar-users-bounces@imperial.ac.uk> on behalf of Gao <feigao2024@126.com> Sent: 18 December 2024 02:11 To: nektar-users <nektar-users@imperial.ac.uk> Subject: [Nektar-users] Questions about Nektar++ | This email from feigao2024@126.com 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 to disable email stamping for this address. | Hello, everyone I have two questions about using Nektar++. First, When I change the initial value to the std file of the previous time step, then the instantaneous result (5.chk, 6.chk...) can come out, but the averge field result didn't appear. Is this normal? And the average field file is output only when the calculation is complete, is the mean field file at this point the result of a continuation run? Second, I am trying to monitor aerodynamic forces in the CompressibleFlowSolver. But it seems that the FilterAeroForces supports only the incompressible solver. Is there any other way to get the aerodynamic force over time? Thanks a lot. With best regards

Dear Vivarelli, Thanks a lot, now it works. Thanks again. With best regards At 2024-12-18 19:10:25, "Vivarelli, Guglielmo A" <guglielmo.vivarelli12@imperial.ac.uk> wrote: Dear Fei Gao, Depends on the frequency you output the file and whether you decide to use the restart option, please refer to the manual for this. You are supposed to used the boundary ID in the session file ("BOUNDARYREGIONS") not the composite ID in the mesh Regards, Guglielmo From: Gao <feigao2024@126.com> Sent: 18 December 2024 10:58 To: Vivarelli, Guglielmo A <guglielmo.vivarelli12@imperial.ac.uk> Cc: nektar-users <nektar-users@imperial.ac.uk> Subject: Re:Re: [Nektar-users] Questions about Nektar++ Dear Vivarelli, Guglielmo A, Thanks for your kind reply. First, perhaps I didn't express myself clearly. In the case where there is already an AverageFields filter, the average field file is not output during the recalculation process, but only after the calculation is finished. Is the final output of this mean field file a continuation result? Second, I have added the AeroForces filiter, the wall is C[16] in the mesh.xml, so I set <PARAM NAME="Boundary">B[16]</PARAM> in AeroForces filiter, but the result of asreforces are all zero. Also I used the <PARAM NAME="Boundary">C[16]</PARAM>, the results are also zero. Am I wrong? With best regards At 2024-12-18 16:03:07, "Vivarelli, Guglielmo A" <guglielmo.vivarelli12@imperial.ac.uk> wrote: Dear Fei Gao, Thank you for your question and interest in using Nektar++, you need to add a "Filter" section at the end of your session file: <FILTERS> <FILTER TYPE="AverageFields"> <PARAM NAME="OutputFile">MyAverageField</PARAM> <PARAM NAME="OutputFrequency">10000</PARAM> <PARAM NAME="SampleFrequency"> 1 </PARAM> </FILTER> <FILTER TYPE="AeroForces"> <PARAM NAME="OutputFile">DragLift</PARAM> <PARAM NAME="OutputFrequency">1</PARAM> <PARAM NAME="Boundary">B[0]</PARAM> </FILTER> </FILTERS> Please see sections "3.5.22 Time-averaged fields" and "3.5.2 Aerodynamic forces", although it says that the "AeroForces" filter does not work with the compressible solver I got it to work with the above. I hope this answers your query. Thanks, Guglielmo From: nektar-users-bounces@imperial.ac.uk <nektar-users-bounces@imperial.ac.uk> on behalf of Gao <feigao2024@126.com> Sent: 18 December 2024 02:11 To: nektar-users <nektar-users@imperial.ac.uk> Subject: [Nektar-users] Questions about Nektar++ | This email from feigao2024@126.com 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 to disable email stamping for this address. | Hello, everyone I have two questions about using Nektar++. First, When I change the initial value to the std file of the previous time step, then the instantaneous result (5.chk, 6.chk...) can come out, but the averge field result didn't appear. Is this normal? And the average field file is output only when the calculation is complete, is the mean field file at this point the result of a continuation run? Second, I am trying to monitor aerodynamic forces in the CompressibleFlowSolver. But it seems that the FilterAeroForces supports only the incompressible solver. Is there any other way to get the aerodynamic force over time? Thanks a lot. With best regards