Set the following scales in physics.data:

lscale	3.08 e+18 cm
rscale	2.02 e-16 g/cm3
tempscale	1 K

From that initialized an ambient object with the following density and pressure,

ambient%rho=2.03d-16/rscale
ambient%pressure=(rhoOut/rscale)*(tempOut/tempscale)

Have my grid running from, gxbounds= -.0068 -.0068 0 .0068 .0068

I ran the sim to frame 0 to get the timescale from scales.data.

I used this to get the tsim=tdiff in computational units,

tsim=2.074e+6s/!338402526430554s = 6.13e-9

Next, I calculated the energy injection rate using the luminosity of a FHSC:

L=3.9e+29 erg s^-1
Lscale=Pscale*(lscale)³/timescale=1.46*10³³
L(cu)=2.67 e-4

Next came scaling the opacities.

The code takes specific opacity (this is in cm²/g), and then asks whether it should be constant, or multiplied by density (or temperature) to some power. I set it to be a power law scaling.

tpow=0
dpow=1

so that,

opacity=kappa*rho

I scaled the planck and rosseland opacities into computational units by:

kappa_r=0.23*mscale/(lscale)²=144.07
kappa_p=.4*mscale/(lscale)²=250.56

Radiation was set to 'diffusion and energy exchange only', rad limiter was set to 'diffusion limit'.

This all seems right to me, so then here are the results.

Run 1

de/dt=7.73246e+5

I calculated the diffusion time assuming the scale-height was = box radius (which also equals the mean free path). Because of this, I thought I was in the optically thick limit everywhere in my box, so chose the flux limiter to be constant… =1/3 in the data file. From this, I calculate the diffusion time to be 24 days. Is this a good estimate?

Why do the wings leave the grid faster than the speed of light?

This has to do with the fact I am not 'limiting' the diffusion through the limiter, when I should be doing that. Show plots of R.

However, the scale height is not the same as the mean free path in actuality, and so it is curious then what it means to calculate a diffusion time in the FLD approximation.

If my entire box was optically thick, I would expect the t_diff=24 days. But since it is not, the wave should diffuse through some parts

Now knowing that my signal is propagating through my medium at an unphysical speed,

Run 2

Same de/dt, but now increasing lambda by factor of 10 (this decreases mean free path by 10x, and thus increases tdiff by 10x).

Run 3

Same de/dt but now with higher lambda

Run 4

Run 1 at lower resolution

Run 5

Run 1 with dynamic lambda

Run 6

Run 3 with dynamic lambda

Run 7

Run 1 with lower density (do we see the temperature /coupling change ?)