Runtime Parameters¶
CosmicGrain combines standard GADGET parameters with runtime switches and calibration values for individual dust processes. This page highlights the parameters most likely to affect reproducibility; it is not a substitute for the parameter-registration table in the source.
Dust process switches¶
Archive the enabled/disabled state of creation, drag, grain growth,
coagulation, shattering, sputtering, shock destruction, astration, radiation
pressure, clumping, and dust cooling. Confirm the parsed state in the startup
[DUST_FLAGS] diagnostic.
Stellar dust sampling¶
| Parameter | Current controlled value | Meaning |
|---|---|---|
DustParticlesPerSNII |
4 | Superparticle samples across a complete SNII event |
DustParticlesPerAGB |
6 | Superparticle samples per AGB event |
DustParticlesPerLRN |
1 | Superparticle samples per LRN event |
DustVelocitySNII |
run parameter | SNII dust birth kick |
DustVelocityAGB |
run parameter | AGB dust birth kick |
Particle counts control numerical sampling. They do not change the physical dust yield when tranche bookkeeping is operating correctly.
Star formation and collisions¶
CritPhysDensity sets the physical star-formation threshold and also provides
the density scale used by the subgrid-clumping prescription. The controlled
feedback test changes only CritPhysDensity from 0.7 to
\(0.1\,\mathrm{cm^{-3}}\); other parameters remain fixed so the effect can be
isolated.
DustCollisionDensityThresh is a separate gate used by coagulation and
shattering. Do not change it implicitly when changing CritPhysDensity.
Resolution-sensitive parameters¶
For each resolution, record gravitational softenings, target gas mass, neighbor count, PM mesh settings, memory allowance, output cadence, and any dust-collision thresholds. Parameters that vary with resolution must be explicitly tabulated rather than inferred from a directory name.