MOCASSIN 2.02 manual
Running models that include dust and gas.
The gas and dust radiative transfer routines in MOCASSIN are now fully integrated. It is therefore now possible to run MOCASSIN in its original gas-only mode, as well as dust-only and of course dust+gas. The basics on how to run the code for dust-only or gas-only cases have already been given in pure photoionisation benchmarks and pure dust benchmarks; here we will concentrate on an example where both dust and gas are present.
Below is the
input.in file used for the dust and gas model of NGC 3918 as described by Ercolano, Barlow and Storey (2005, MNRAS, 362, 1038).
autoPackets 20. 2. 500000000 densityFile 'ngc3918/ngc3918den.dat' symmetricXYZ multiChemistry 2 'ngc3918/ngc3918.dat' 'ngc3918/ngc3918.dat contShape 'ngc3918/nLTe140lg65' maxIterateMC 30 95. nPhotons 1000000 nx 23 ny 23 nz 23 nbins 700 LStar 27.64 nuMax 23.7 nuMin 3.1e-4 Rin 0. Rout 3.27142e17 TStellar 140000. MdMh constant 0.0011 dustFile 'ngc3918/primary_grainspecies.dat' 'ngc3918/primary_grainsizes.dat' writeGrid 50. convLimit 0.03 resLinesTransfer 90.
In summary, it should be clear from the example above that the only keywords that differentiate the file above from the input of a gas-only model are:
- MdMh (dust to hydrogen mass ratio)
- dustFile (files containing the grain size distribution and species information)
- resLinesTransfer (which tells at what level of grid convergence the resonance line photons escape fractions should be calculated).
Note that the first two keywords that define how much, what type and what size grains are to be used is also needed to run dust-only models (although MdMh could be substituted by Ndust or by MdMg). resLinesTransfer is only needed if there is gas also in the simulation (which would then be emitting resonance lines capable of heating the grains).
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