[FLASH-USERS] Magnetized Inflow: Torus Problem

[Ryan Farber]

Dear FLASH users,

TL;DR: Setting xl_boundary_type = "user", cells are filled with zero
density although Grid_bcApplyToRegionSpecialized was not yet called. There
is no such problem with all periodic BCs. If someone familiar with user BCs
could mention which additional routines are executed that I might want to
look into to debug this problem I'd very much appreciate it.

=========================================================

I am trying to modify the Torus problem included in FLASH4.5 to include a
magnetized inflow from the lower x-boundary.

So, I modified flash.par to turn off gravity, comment out gr_prmp*
variables, set geometry to cartesian, lrefine_min = 3, and set all BCs to
periodic except xl_boundary_type = "user".

Additionally, I modified Simulation_initBlock so the domain is initially at
a uniform density and temperature with zero velocity and zero magnetic
field.

When I run the simulation with all BCs set to periodic, I receive many
warning messages about the density being the value I set (modulo roundoff
error) with a lot of output (possibly printing the entire density array?);
however, it runs to completion fine and plots show the domain remained
uniform (as to be expected).

However, when I set xl_boundary_type = "user" then the warning messages say
minimum density is -1.0 and it crashes with:

ERROR After calling Eos, eosData(EOS_EINT) or eosData(EOS_DENS) are zero

Compiling with -debug I receive a "floating invalid" error with traceback
to eos_idealGamma.F90 with a line in which there is a division by density
(which is zero, triggering the floating invalid error). However, I have
write statements at the start of Grid_bcApplyToRegionSpecialized that are
never executed suggesting that routine is not called yet.

I am seeking to eliminate this zero density issue; I'd be very grateful for
any pointers those familiar with user BCs could point out.

Best,
--------
Ryan Farber
PhD Candidate, University of Michigan
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