[Nek5000-users] double mesh ?

[nek5000-users at lists.mcs.anl.gov]

Dear Agnese,

Attached is an example that shows how to modify the connectivity for the thermal
field to be inflow/outflow.

If your domain is generated with genbox and your flow is in the x direction then
this should also work for 3D.

Note that no changes are required to the .rea file (you should have "P  " for both
velocity and temperature in the .rea/.box file).

The changes occur in the .usr file.

Paul

________________________________
From: nek5000-users-bounces at lists.mcs.anl.gov [nek5000-users-bounces at lists.mcs.anl.gov] on behalf of nek5000-users at lists.mcs.anl.gov [nek5000-users at lists.mcs.anl.gov]
Sent: Monday, January 16, 2017 9:31 AM
To: nek5000-users at lists.mcs.anl.gov
Subject: Re: [Nek5000-users] double mesh ?

Dear Paul

thank you so much for your help !
I am looking forward to see your example, it will be of great help !

could you tell me something more about the recycling BC as well ?

Thank you again for your help
Agnese


From: nek5000-users at lists.mcs.anl.gov<mailto:nek5000-users at lists.mcs.anl.gov>
Subject: Re: [Nek5000-users] double mesh ?
Date: January 16, 2017 at 4:05:21 PM GMT+1
To: "nek5000-users at lists.mcs.anl.gov<mailto:nek5000-users at lists.mcs.anl.gov>" <nek5000-users at lists.mcs.anl.gov<mailto:nek5000-users at lists.mcs.anl.gov>>
Reply-To: nek5000-users at lists.mcs.anl.gov<mailto:nek5000-users at lists.mcs.anl.gov>

Dear Agnese,

Sorry for the long delay in answering this question.  The issue is that in fact it is possible
(and used to be a supported but rarely used feature).   The challenge, however, is how to
make it relatively easy in the context of the current setup for a variety of applications.

Nek supports a different gather-scatter handle for each field (velocity, temperature, passive
scalar, etc.)

We have a handle that allows the user access to the connectivity list, which would give
you an opportunity to "disconnect" the periodic faces for the temperature array.

I'll try to code up an example for the case of channel flow with a mesh generated by
genbox and post it shortly.

Incidentally, an alternative approach that we often use for more complex domains
would be to use a recycling boundary condition.   I think it would not be as efficient,
however, as periodicity for the case that you propose.

Once again, apologies for the delayed response.

Paul

________________________________
From: nek5000-users-bounces at lists.mcs.anl.gov<mailto:nek5000-users-bounces at lists.mcs.anl.gov> [nek5000-users-bounces at lists.mcs.anl.gov<mailto:nek5000-users-bounces at lists.mcs.anl.gov>] on behalf of nek5000-users at lists.mcs.anl.gov<mailto:nek5000-users at lists.mcs.anl.gov>[nek5000-users at lists.mcs.anl.gov<mailto:nek5000-users at lists.mcs.anl.gov>]
Sent: Thursday, December 22, 2016 4:38 AM
To: nek5000-users at lists.mcs.anl.gov<mailto:nek5000-users at lists.mcs.anl.gov>
Subject: [Nek5000-users] double mesh ?

Hi

i am quite new, so i’m sorry if i’m getting things wrong.

I am trying to simulate a turbulent channel flow, with a passive scalar.
in the streamwise direction, i would like to impose periodic boundary conditions for the flow, and non-periodic for the scalar.
in fact the scalar has a point source near the inlet, and i want to see how that develops downstream.

as far as i understand this is not supported by nek5000, because the last mesh point is identified with the first mesh point when periodic BC are imposed.
correct ?

my question is : could i define two meshes, one for the scalar and one for the velocity ?

thanks a lot for your help !!!
agnese


Agnese Seminara
--------------------------------
CNRS
Laboratoire de physique de la matière condensée
Parc Valrose
avenue J Vallot
06108 Nice, France
+33 (0) 492 076 775
http://sites.unice.fr/site/aseminara/



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