[FLASH-USERS] Question / potential bug in EOS

[pchang]

Hi all,
I am benchmarking Flash to a 1D code in our lab and the calculated 
numbers and see if they give the same result. And I found some results 
that indicates some issues / potential bug in EOS.
In my test, I setup an initial temperature with an initial density of D2 
gas. To simplify the problem, I used fully ionized ideal gas model, 
which I believe it's what eos_gam stand for. The eos mode I had were 
eosModeInit="dens_temp_gather" and eosMode="dens_ie_gather". During the 
test, I kept the gas density fixed to be 1.6mg/cc. Then I varied the 
initial temperature. Since I used +mtmmmt in my setup, so I need to give 
the electron, the ion, and the radiation temperature, but I kept them 
all the same to each other during the test. When I had the temperature 
equal to 2.9e2 Kelvin (0.025eV), it gave a pressure of  ~4e7 dyne/cm2. 
This number matches the 1D code and the calculated pressure using the 
ideal gas model. Then, I increased the temperature and see what's the 
pressure I got. In ideal gas model, the pressure scales linearly versus 
temperature. However, when I had the temperature of 2.9e6 Kelvin 
(250eV), the pressure deviated from our 1D code and the ideal gas model. 
In stead of getting ~4e11 dyne/cm2, I got 5.7e11 dyne/cm2. When I 
increased the temperature to 2.9e7 Kelvin (2.5keV), the pressure was 
1.8e15 dyne/cm2 instead of ~4e12 dyne/cm2 from ideal gas model. The much 
higher pressure can make big impact on hydrodynamic! In fact I tried 
using tabulated sesame table, they gave the same result!

I don't know if any encounter this issues? Is it a potential bug in the 
eos package?

Thanks,

Po-Yu


-- 
Po-Yu Chang

Postdoctoral Associate
The Department of Energy's Advanced Research Projects Agency-Energy (ARPA-E)
Department of Mechanical Engineering,
Fusion Science Center for Extreme States of Matter,
Laboratory for Laser Energetics
University of Rochester
250 East River Road
Rochester, New York 14623
Phone: (585) 273-5179
FAX: (585) 275-5960
pchang at lle.rochester.edu