[FLASH-USERS] EOS for guard cells

[Maksim Kozlov]

Dear flash users,
I would really appreciate it if somebody helps me with the following issue.
I am experimenting with the equation of state (EOS). Don't ask me how it is
possible but my pressure becomes negative sometimes. To make sure that
sound speed is real, after calculating Gamma=Cs^2*rho/P (Gamma is GAMC, P
is pressure, rho is density, Cs is sound speed). I am checking if  Gamma*P
is positive (density is always positive). And  Gamma*P   is always positive
in subroutine EOS. However  I receive an error  message from subroutine
hy_uhd_shockDetec because Gamma*P/rho becomes negative so sound speed
becomes imaginary. What I know is that it happens in guard cells only.
However I do not understand how it can happen. Somewhere on the way from
subroutine EOS to subroutine hy_uhd_shockDetect  Gamma*P in guard cells
becomes negative yet as far as I understand both Gamma and P are calculated
only in EOS.
Many thanks!
MAksim

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