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

[Acharya, Nitish]

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.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://flash.rochester.edu/pipermail/flash-users/attachments/20210401/36160274/attachment.htm>