[FLASH-USERS] [EXT] Equation of state error

[kyv005 at campus.mephi.ru]

Dear Nitish,

Thank you for the quick response.
Yes, I have checked my EoS for negative pressures, and currently all of 
them are strictly > 0. So the issue is probably caused by something 
else.

Best regards,
Iurii K.


Acharya, Nitish писал 2021-04-01 20:57:
> Hi Lurii,
> 
>  The issue might also come from negative pressures in the EOS. Did you
> check that? I had the similar issues in the past while using some
> SESAME EOS tables.  Those tables used negative pressures to emulate
> tension which is not ok with FLASH's solvers as it will make the
> thermal sound speed imaginary.
> 
>  Thanks,
>  Nitish
> 
> -------------------------
> 
> FROM: flash-users-bounces at flash.uchicago.edu
> <flash-users-bounces at flash.uchicago.edu> on behalf of
> kyv005 at campus.mephi.ru <kyv005 at campus.mephi.ru>
> SENT: Thursday, April 1, 2021 1:47 PM
> TO: flash-users at flash.uchicago.edu <flash-users at flash.uchicago.edu>
> SUBJECT: [EXT] [FLASH-USERS] Equation of state error
> 
> Dear Flash users,
> 
> I am trying to run a LaserSlab simulation for my own target material
> with the tabulated EoS.
> 
> The simulation runs fine for some time, but at some point it starts
> throwing 'Eos: negative dE/dT is bad!' errors in the output file, and
> then it stops with the following message: 'DRIVER_ABORT:
> [hy_uhd_eigenParameters-A]: Zero or imaginary sound speed has
> obtained!
> Please try other (more diffusive) slope limiter, flux, order, cfl,
> etc.'
> 
> I know the problem is with my EoS, since the same simulation runs
> without errors if I use the tables from FLASH. However, I cannot
> figure
> out what is wrong with my EoS - there should be no unphysical things
> that could possibly lead to negative sound speed and etc. in it. I
> have
> tried several of the suggested options (reducing cfl, changing slope
> limiters and etc.), but this did not solve the problem.
> 
> So can you, please, help me determine what I might be doing wrong and
> how I can avoid these errors?
> 
> Thank you in advance for your suggestions,
> 
> Best regards,
> Iurii K.