[Nek5000-users] Error in generalev with MHD

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

Hi Jan and SL,


Good point, SL, about the line 5912 but I suspect the problem lies in the fact that in our MHD implementation we only focused on 'v  ' type boundary condition and hot on 'V  ' so, Jan, I suggest to modify 'V  ' to 'v  ' and use userbc() to set zero BC for ifield=ifldmhd

Let me know if you have any questions.

Aleks
 
________________________________________
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: Tuesday, July 01, 2014 7:51 AM
To: nek5000-users at lists.mcs.anl.gov
Subject: Re: [Nek5000-users] Error in generalev with MHD

Hi Jan,

On line 5912, velocity BC is written with capital letter V instead of
small letter v (as in 5928).

If you write velocity with small letter, it'll read the BC in the .usr
file (userbc subroutine), otherwise you have to specify the values of
velocity in the .rea file.

In addition, in the elements (E) BC you have to specify

E     n1    n2   n3   n4   0  0  0
n1: Number of element
n2: side of element
n3: element connected
n4: side of the element connected.

However, you've set n3 and n4 to 0.

I hope it helps you.

Regards,
SL



El 01-07-2014 13:56, nek5000-users at lists.mcs.anl.gov escribió:
> Hello Neks,
> I' trying to solve the MHD equations and encounter the same error
> reported here:
> http://lists.mcs.anl.gov/pipermail/nek5000-users/2011-June/001365.html.
> For testing, I have set up a small grid (384 elements) with B=0 at the
> boundaries and B=0 as initial conditions, and the error appears before
> the first timestep. As mentioned in the documentation, I have used the
> same BC-types for the B Field as for the velocity, so in the .rea file
> it reads:
>
> 5909   ***** PASSIVE SCALAR 1  BOUNDARY CONDITIONS *****
> 5910  E    1  1   0.00000       0.00000       0.00000 0.00000
> 0.00000
> 5911  E    1  2   0.00000       0.00000       0.00000 0.00000
> 0.00000
> 5912  V    1  3   0.00000       0.00000       0.00000 0.00000
> 0.00000
> 5913  E    1  4   0.00000       0.00000       0.00000 0.00000
> 0.00000
> 5914  E    1  5   0.00000       0.00000       0.00000 0.00000
> 0.00000
> 5915  E    1  6   0.00000       0.00000       0.00000 0.00000
> 0.00000
> 5916  E    2  1   0.00000       0.00000       0.00000 0.00000
> 0.00000
> 5917  E    2  2   0.00000       0.00000       0.00000 0.00000
> 0.00000
> 5918  E    2  3   0.00000       0.00000       0.00000 0.00000
> 0.00000
> 5919  E    2  4   0.00000       0.00000       0.00000 0.00000
> 0.00000
> 5920  E    2  5   0.00000       0.00000       0.00000 0.00000
> 0.00000
> 5921  E    2  6   0.00000       0.00000       0.00000 0.00000
> 0.00000
> 5922  E    3  1   0.00000       0.00000       0.00000 0.00000
> 0.00000
> 5923  E    3  2   0.00000       0.00000       0.00000 0.00000
> 0.00000
> 5924  E    3  3   0.00000       0.00000       0.00000 0.00000
> 0.00000
> 5925  E    3  4   0.00000       0.00000       0.00000 0.00000
> 0.00000
> 5926  E    3  5   0.00000       0.00000       0.00000 0.00000
> 0.00000
> 5927  E    3  6   0.00000       0.00000       0.00000 0.00000
> 0.00000
> 5928  v    4  1   0.00000       0.00000       0.00000 0.00000
> 0.00000
> 5929  E    4  2   0.00000       0.00000       0.00000 0.00000
> 0.00000
> 5930  E    4  3   0.00000       0.00000       0.00000 0.00000
> 0.00000
> etc.
>
> The thread above mentioned that it was due to incorrect BCs, but
> unfortunately no more details were given.
>
> Cheers,
> Jan
>
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