[Nek5000-users] Error in generalev with MHD

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

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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