[Nek5000-users] uservp MHD error

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

Hi Sandeep,

The MHD implementation in Nek5000 works only for constant properties so far but it is possible to generalize it to a case with ifuservp=.true.  Let me know if you want to discuss this offline: obabko at mcs.anl.gov

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: Thursday, December 01, 2016 11:31 AM
To: nek5000-users at lists.mcs.anl.gov
Subject: [Nek5000-users] uservp MHD error

Hello All,

I want to run MHD case with different magnetic diffusivities in different region of the domain.
Can we run MHD run with different magnetic diffusivities?
Assuming that udiff=magnetic diffusivity (eta), in the uservp file I added the following

      1.0000000E+00     p30 > 0 ==> properties set in uservp()

      subroutine uservp (ix,iy,iz,ieg)
      include 'SIZE'
      include 'TOTAL'
      include 'NEKUSE'

      if (ifield.eq.1) then ! velocity
utrans = param(1)
udiff  = param(2)
      elseif (ifield.eq.ifldmhd) then ! B-field
utrans = 1.0
        R1 = sqrt(x*x+y*y);
if(R1 .le. 2.0) then
udiff= param(29)
else
udiff= 1000.0D0*param(29)
endif
 endif

      return
      end

I get an error

 done :: set initial conditions

  ERROR:  Non-positive diffusivity (    0.00    ) specified for field 2, group 0 element
  ERROR:  Non-positive diffusivity (    0.00    ) specified for field 2, group 0 element

Attached are the .usr, .rea and the logfile

When I set the p30=0.000 and just utrans=0.0 udiff=0.0 in the uservp, the simulation is running fine.
Thank you in advance.

Cheers,
Sandeep


-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.mcs.anl.gov/pipermail/nek5000-users/attachments/20161201/34636a48/attachment.html>