[Nek5000-users] Follow up: rotating disk with periodic boundaries (Nek5000-users Digest, Vol 37, Issue 20)

Wed May 2 05:09:46 CDT 2012

Dear Nek users,

earlier I wrote an e-mail concerning how to make an element periodic
with itself (see below). The goal was to decrease the domain of my
simulation over a rotating disk.

I've now tried three different mesh setups where I don't need to make
the element periodic with itself in two of them. Currently, I also try
to use the cyclic boundary conditions which in my opinion should work.
However, it doesn't. I still get the communication error in Nekton (see
email below) and also I get an error from genmap. I attached a folder
with figures of my meshes (named a,b,c from left to right) and necessary
files in order to run the case.

Do you think that the cyclic boundary conditions should work for my
case? Maybe there is a quick-fix for this communication error? Or do you
have any other suggestion on how to do this?
I would like to avoid to remap the grid from a straight to a curved one
since I would like to have fewer elements toward the center of the disk.

Best regards,
Ellinor

On 03/28/2012 12:27 PM, nek5000-users-request at lists.mcs.anl.gov wrote:
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>    1. rotating disk with periodic boundaries
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> Message: 1
> Date: Wed, 28 Mar 2012 12:27:25 +0200
> From: nek5000-users at lists.mcs.anl.gov
> Subject: [Nek5000-users] rotating disk with periodic boundaries
> To: nek5000-users at lists.mcs.anl.gov
> Message-ID: <4F72E78D.5000802 at mech.kth.se>
> Content-Type: text/plain; charset="iso-8859-1"
>
> Dear nek users,
> I am doing simulations over a rotating disk with nekton and would like to
> decrease my domain in order to save computational time.
>
> The mesh is currently very similar to that of a pipe, with inflow in one
> end
> (max(z)) and a rotating wall in the other end (z=0). Around the curved
> edges I use the outflow boundary condition.
>
> The way I would like to decrease the domain in is by using periodic
> boundary conditions in the rotational direction, that is cutting the
> pipe in the
> z-direction to only use a third or a quarter of the pipe.
>
> My problem is that when I try to do this, I have to make one element
> periodic
> with itself, this is since I would like to have few elements in the
> middle of
> the domain and thus not want to use the cylindrical coordinates.
>
> In some setups, I recieve an error when using genmap (when trying
> different mesh
> tolerance numbers), and in some setups I get a communication error when
> running
> the code;
>
>
> genmap error:
>
>   4   z1    0.0000E+00  1.5224E-01  1.5224E-01  0.0000E+00
>        2 3  3  1.00000005E-03  1.00000000E+00 abort: FACE MATCH FAIL
>        7 4  5  1.00000005E-03  2.54558474E-01 abort: FACE MATCH FAIL
>
>
> communication error:
>
> veryfy mesh topology ...
> ...
> ...
> WARNING1 Element mesh mismatch at:
> i,j,k,ie:    1    1    1    1
> Near X = 0.59397000    0.59397000    0.00000000    , d:    0.0000000  
>  -0.11313799    1.4142136
> ...
> ...
>
>
>
> The type of error seem to depend on how the elements are numbered in the
> domain.
>
> I've understood that for using the periodic boundary conditions, one
> need at
> least three elements. Is there a way around this when it comes to my setup?
> Or would there be an easy fix for this problem?
>
>
> Best regards,
> Ellinor
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> End of Nek5000-users Digest, Vol 37, Issue 20
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