Posts by author mccann

Ionization

Time stepping too large currently for parameters.

To mimic Anjali's low flux case but instead with a solid sphere, let's use an ideal gas with the following setup:

, , , , , , .

Grid aligned effects

With the the planet creation correctly implemented, I've now rediscovered the grid aligned effects. Increasing resolution does not seem to resolve the issue, it only seems to exacerbates the issues of the grid aligned effects. That being the time step during the grid aligned effects is significantly smaller than after the planet reaches a steady state. At higher resolution it seems to use smaller time steps to resolve the effects.

Hydrostatic equilibrium planetary atmosphere

AstroBEAR Planetary HSE

Currently the "hydrostatic" atmosphere is diffusing into the ambient. These runs take a couple of hours to get a few frames on 120 cores. From the images (left density, right pressure.) it appears the core of the planet is not being reset every time step as I intended it to. This is attempted by mimicking how the star is reset in your simulations; with the "surface" being the masked area of constant values deep interior the planet, and the "envelope" being the layer with variables as a function of and held steady. This is significantly different than the issue I had before and I am looking into why it has arisen. I'll email source code shortly.

This could also be a resolution issue judging by the images. I don't see any further refinement (GmX=643), when my global.data asked for 4 additional SMR levels (MaxLevel=4, LastStaticLevel=-1). Either the chombos or my Visit techniques are failing to plot the higher resolution I thought I had, or I misused the refinement feature in AstroBEAR.

Radiative Transfer in ATHENA

The primary radiative energy considerations were previously recorded by Jonathan back in January ​(link). For reference on cooling rates, the recombination rate is taken from Osterbrock (1989), pg. 19 and Lyman alpha from Black (1981).

To prevent large transients from the initial ionization of the neutral planet, the incoming flux is ramped by the function

The two constants within the error function prescribe when the function is at half value and the speed at which it ramps. Note and