[FLASH-USERS] Imaginary sound speed error in EOS

[Kazuki Matsuo]

Dear Nitish ,

1) I assume FLASH calculates sound speed from these EOS tables using c =
sqrt(gamc*pres/dens). When I looked in the tables, I found a lot of
negative pressure data in the EOS. Is that the reason I might be getting
this error? How should I deal with it?

I also tried to use SESAME table with FLASH and other codes.
But I can't get some results because of the imaginary sound speed problem
you mentioned.

2) What are other options for getting EOS tables of materials for use in
FLASH? FLASH seems to only have IONMIX4 tables of He, Al and Polystyrene.

So one way is you remove negative pressure data from the table. (I am not
sure it is correct or not)

Another way I suggest you to use PROPACEOS code to calculate Opacity and
EOS.
If the material Z number < 36(Kr), PROPACEOS can provide Opacity and EOS
data very easily. From the calculation result, you can make .cn4 file for
FLASH.

For more high Z material, I try to use FLYCHK to calculate Opacity and our
code to calculate EOS and make .cn4 file for FLASH.
I need more time to produce this so I think PROPACEOS code is a good
choice.

Thanks,

-----

Kazuki Matsuo

Facebook:   https://www.facebook.com/kazuki.matsuo.102
<https://www.facebook.com/kazuki.matsuo.102>

Institute of Laser Engineering Osaka University

2-6 Yamada-oka, Suita, Osaka, 565-0871, Japan

E-mail:   matsuo-k at ile.osaka-u.ac.jp




On Tue, Dec 3, 2019 at 2:37 AM Acharya, Nitish <nachary2 at ur.rochester.edu>
wrote:

> Dear flash-users,
>
> I've been trying to use sesame EOS tables of Aluminum, Titanium and
> Plastic materials for a LaserSlab based simulation in FLASH. I've been
> getting this error
>
> *"Imaginary sound speed has obtained in hy_uhd_HLLC solver...."*
>
> 1) I assume FLASH calculates sound speed from from these EOS tables using
> c = sqrt(gamc*pres/dens). When I looked in the tables, I found a lot of
> negative pressures data in the EOS. Is that the reason I might be getting
> this error? How should I deal with it?
>
> 2) What are other options of getting EOS tables of materials for use in
> FLASH? FLASH seems to only have IONMIX4 tables of He, Al and Polystyrene.
>
> Thanks,
> Nitish
>
>
> ---------------------------
>
> Nitish Acharya
>
> PhD Student
>
> Department of Mechanical Engineering
>
> University of Rochester
>
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