Hi Boyang

Thanks for your reply. I am actually going to change some setup to see if it solves my problem. I have also tried Taylor-Hood but it is not working!
The problem is that when I use p=6 or higher, I get a laminar-like (no transient) flow field! I don't know what could be wrong, numerical setup or something else maybe!

I have given a quite thorough description of the problem, including two snapshots of the instantaneous flow fields. For convenience, I will send you the conversation.
Please let me know if you have any ideas as to how this can be fixed.

Kind regards
syavash








On Mon, May 15, 2023 at 3:55 PM Boyang Xia <boyang.xia@kcl.ac.uk> wrote:
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?


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
 

This email from eh.asgari@gmail.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.

 

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