[FLASH-USERS] output question and very low densities issue

[Antoine Gintrand]

Dear flash users,

I have two differents problems regarding FLASH,


1) I would like to know if it is possible to ask FLASH (in the par file or
somewhere else) to give plot output with less resolution than the check
output. The problem is that I need big resolution for my simulation but it
becomes difficult to open them and analyse them in Visit and I would like
to have output to analyse with less size than the data used for the real
calculation.

2) my second problem is that I am simulating two supersonic flows that
collide in the interstellar medium (in 2D) where the initial conditions are
two flows in opposite directions.

The first fluid 1 in the left is defined with Density = 1.E-24, Velocity =
1.E10, Pressure = 1.E-5
The second fluid 2 in the right is defined with Density = 1.E-24, Velocity
= 1.E10, Pressure = 1.E-7

box size = 1.E13 * 1.E13  (all values are in CGS as FLASH convention)

when I begin the simulation I have the following error :

 INFO: Grid_fillGuardCells is ignoring masking.
 [ 09-18-2020  11:02:30.747 ] [mpi_amr_comm_setup]: buffer_dim_send=46871,
buffer_dim_recv=46871
 [ 09-18-2020  11:02:30.805 ] WARNING after gc filling: min.
unk(DENS_VAR)=0.9999999999999999237005E-24 PE=0 block=1 type=1
 [ 09-18-2020  11:02:30.883 ] WARNING after gc filling: min.
unk(DENS_VAR)=0.9999999999999999237005E-24 PE=0 block=2 type=1
 [ 09-18-2020  11:02:30.977 ] WARNING after gc filling: min.
unk(DENS_VAR)=0.9999999999999999237005E-24 PE=0 block=3 type=1
 [ 09-18-2020  11:02:30.997 ] WARNING after gc filling: min.
unk(DENS_VAR)=0.9999999999999999237005E-24 PE=0 block=4 type=1

I tried to change the initial conditions and it seems that the problem is
that I cannot have initial densities below 1.E-10. But I need to simulate
densities below these values in an astrophysical context. What can I do to
solve this issue ?


Thank you for your help,

Best,

Antoine Gintrand
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