Hi Silvia, Regarding "What is the way to know which composite ID corresponds to the related physical surface of your geometry?", how I do it is have a look in the .msh file (of gmsh) in a text editor (or head/tail command in linux) and it tells me the relation between the composite ID and the name: """ $MeshFormat 2.2 0 8 $EndMeshFormat $PhysicalNames 5 2 1 "inlet" 2 2 "outlet" 2 3 "walls" 2 4 "sphere" 3 5 "domain" $EndPhysicalNames $Nodes 2721 ... """ I have not checked your session file but hopefully it matches the above, fingers crossed. PS. May be you are already doing this but do not forget to curve the sphere's linear mesh (either using gmsh or spherigons in NekMesh). BR, Vishal --- *Vishal SAINI* On Sat, Apr 11, 2020 at 6:57 AM Silvia Ceccacci (HDR) < silvia.ceccacci@hdr.mq.edu.au> wrote:

Hi Stan,

Thank you for your email.

That was the mistake I was making, indeed. Thank you for noticing. Also thank you for the remarks on the composite IDs and boundary conditions.

Kind regards, Silvia ------------------------------ *From:* nektar-users-bounces@imperial.ac.uk < nektar-users-bounces@imperial.ac.uk> on behalf of Stanisław Gepner < sgepner@meil.pw.edu.pl> *Sent:* Friday, 10 April 2020 9:36 PM *To:* nektar-users@imperial.ac.uk <nektar-users@imperial.ac.uk> *Subject:* Re: [Nektar-users] Flow around a sphere

Hi Silvia,

In your session file you have parameters setup with a slight mistake. You have:

<PARAMETERS> <P> TimeStep = 0.001 </P> <P> NumSteps = 10.0 </P> <P> NumSteps = FinalTime/TimeStep </P>

You should have:

<PARAMETERS> <P> TimeStep = 0.001 </P> <P> FinalTime = 10.0 </P> <P> NumSteps = FinalTime/TimeStep </P>

You are missing the *FinalTime* parameter.

Concerning the boundary conditions and surface Id. I think the way you describe is the way it works. In my workflow I usually give physical surfaces a number instead of a string name:

...

Physical Line(7) = {tab_wall[]}; Physical Line(8) = {inn_id}; Physical Line(9) = {out_id};

...

than in the xml mesh file I have this produced by NekMesh:

<C ID="7"> E[ ...</C> <C ID="8"> E[0,88,147,206,265,324,383,442,501,560] </C> <C ID="9"> E[1227,1169,1111,1053,995,937,879,821,763,704] </C>

and in the session file:

<BOUNDARYREGIONS>

<B ID="0"> C[7] </B> <B ID="1"> C[8] </B> <B ID="2"> C[9] </B>

Cheers!

Stan

W dniu 4/10/20 o 4:08 AM, Silvia Ceccacci (HDR) pisze:

This email from silvia.ceccacci@hdr.mq.edu.au 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 all,

I hope this email finds you all well.

I am trying to simulate flow around a sphere. I get an error of segmentation fault. I am generating a mesh from gmsh, converting it into Nektar format, then using the IncNavierStokesSolver. I am wondering whether it may be a problem with the association of composite IDs in boundary conditions. However I do not seem to find the problem. I attach the files I am using. If anyone could have a look and help me understand what I am doing wrong I would be very grateful.

Anyways, I also have another question that may be related with the issue above. What is the way to know which composite ID corresponds to the related physical surface of your geometry? In other words, is there a way to associate a composite ID to a specific surface in order to assign boundary conditions? For example, in my case, in file s_session.xml, I say C[1] (ID="0") is the inlet surface because in file s.xml it is the first composite, which, I am assuming, corresponds to the first physical surface I have defined in file s.geo (Physical Surface("inlet")={2};). Is this correct? I hope my questions make sense.

Thank you in advance for your help, and Happy Easter!

Kind regards, Silvia

_______________________________________________ Nektar-users mailing listNektar-users@imperial.ac.ukhttps://mailman.ic.ac.uk/mailman/listinfo/nektar-users

_______________________________________________ Nektar-users mailing list Nektar-users@imperial.ac.uk https://mailman.ic.ac.uk/mailman/listinfo/nektar-users