Thank you both for clarifying this. Kind regards syavash On Mon, May 15, 2023, 18:58 Sherwin, Spencer J <s.sherwin@imperial.ac.uk> wrote:
Dear all,
We should not be using the RadauMAlpha1Beta0 with Hex elements. This stands for Radau distribution at minus 1 (i.e. not including the point at +1) but it also involves the weight 0.25 (1-x)^alpha (1+x)^beta. So the Alpha1 means you are adding a weight function of 0.5(1-x)^alpha into the integral which is naturally part of the collapsed coordinate transform but this is not required in a Hex.
So in theory one could use RadauMAlpha0Beta0 (not sure if this actually exists) but would be best just to use GaussLobattoLegendre in all directions.
Cheers,
Spencer.
*From: *nektar-users-bounces@imperial.ac.uk < nektar-users-bounces@imperial.ac.uk> on behalf of Boyang Xia < boyang.xia@kcl.ac.uk> *Date: *Monday, 15 May 2023 at 16:19 *To: *Ehsan Asgari <eh.asgari@gmail.com> *Cc: *nektar-users <nektar-users@imperial.ac.uk> *Subject: *Re: [Nektar-users] potential bug with detailed expansion
Hi,
GaussRadauMAlpha1Beta0 seems to be often used in Tri and Tet with Modified_B. I am not sure if it works with Modified_A(Ideally it should). So, what is your consideration of using GaussRadauMAlpha1Beta0 on the 3rd direction of hex?
Are you using the incompressible Navier-Stokes solver and VCS? Then maybe you should follow chapter 11.1.1.6 to set different number of modes and points for velocity and pressure field.
https://doc.nektar.info/userguide/5.3.0/user-guidese44.html
Hope it helps, or correct me if it's wrong.
Thanks,
Boyang
------------------------------
*From:* nektar-users-bounces@imperial.ac.uk < nektar-users-bounces@imperial.ac.uk> on behalf of Ehsan Asgari < eh.asgari@gmail.com> *Sent:* Monday, May 15, 2023 11:53 *To:* Jacques Xing <jacques.xing@kcl.ac.uk> *Cc:* nektar-users <nektar-users@imperial.ac.uk> *Subject:* Re: [Nektar-users] potential bug with detailed expansion
Hi Jacques
I have a fully hex mesh. My perception is that for hex elements, modified_a should be used.
Please correct me if I'm wrong.
syavash
On Mon, May 15, 2023 at 3:11 PM Jacques Xing <jacques.xing@kcl.ac.uk> wrote:
Hi Ehsan
I believe that you should use Modified_B basis from GaussRadauMAlpha1Beta0 quadrature. I am also assuming that you are using prism elements for the mesh?
https://doc.nektar.info/userguide/5.0.0/user-guidese7.html
Best,
Jacques ------------------------------
*From:* nektar-users-bounces@imperial.ac.uk < nektar-users-bounces@imperial.ac.uk> on behalf of Ehsan Asgari < eh.asgari@gmail.com> *Sent:* Monday, May 15, 2023 9:29 AM *To:* nektar-users <nektar-users@imperial.ac.uk> *Subject:* [Nektar-users] potential bug with detailed expansion
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Dear All,
When I use a "Modfied" type for expansions everything works fine. But if I specify the expansions in detailed mode:
<E COMPOSITE="C[30011]" BASISTYPE="Modified_A,Modified_A,Modified_A" NUMMODES="7,7,7" POINTSTYPE="GaussLobattoLegendre,GaussLobattoLegendre,GaussRadauMAlpha1Beta0" NUMPOINTS="8,8,7" FIELDS="u,v,w" /> <E COMPOSITE="C[30011]" BASISTYPE="Modified_A,Modified_A,Modified_A" NUMMODES="6,6,6"
POINTSTYPE="GaussLobattoLegendre,GaussLobattoLegendre,GaussRadauMAlpha1Beta0" NUMPOINTS="7,7,6" FIELDS="p" />
Then I get a bunch of errors:
[xxx518:29773] *** Process received signal *** [xxx518:29773] Signal: Segmentation fault (11) [xxx518:29773] Signal code: Address not mapped (1) [xxx518:29773] Failing at address: 0x27b2000
I have a fully hex mesh.
Could you kindly point out if something is wrong with the way I specify the expansions?
Kind regards
syavash