[FLASH-USERS] MGD opacity tables for un-ionized gas and dust cloud collapse problems

[Boss, Alan]

I am trying to use FLASH4.3’s multigroup diffusion (MGD), flux-limited
diffusion (FLD), radiative hydrodynamics (RHD) routines to reproduce
classical results (e.g., Larson 1969) for the collapse of a dense cloud of
molecular gas and dust to form a protostar, most recently recalculated in
spherical symmetry by N. Vaytet et al. (2013, A&A, 557, A90), using an
implicit Lagrangean RHD code. While M. Klassen et al. (2014, ApJ, 797, 4)
showed that the FLASH4.0 MGD FLD routines performed well on various RHD
tests, they did not include any tests involving self-gravity or dynamic
collapse. FLASH4.3 does not appear to contain any test problems that
involve both MGD FLD and gravity solvers such as multipole and multigrid.
Starting from the /radflaHD/CriticalRadShock simulation, I have been able
to include gravity using both options and to run a variety of protostellar
collapse test cases, using the Constcm2g opacity routine. In order to try
to better match the previous work, I now need to consider a tabulated
opacity (as used by Vaytet et al. and Klassen et al.) rather than a
constant opacity. The FLASH4.3 users guide suggests using the IONMIX4
format to store opacity tables, but this format seems to be specialized to
highly ionized situations, whereas dense molecular cloud cores are ~ 10 K
and not ionized. Klassen et al. were able to include tabulated Rosseland
mean opacities in their RHD test cases, but I have not found any clues
about how to include such un-ionized opacities in FLASH4.3. I would
appreciate any suggestions for how to handle un-ionized opacity regimes, as
well as references to any work done so far on using FLASH4.3 MGD on
self-gravitating collapse problems. Thanks! ... Alan Boss

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Dr. Alan P. Boss
Department of Terrestrial Magnetism
Carnegie Institution for Science
5241 Broad Branch Road, N.W.
Washington, D.C. 20015-1305 U.S.A.
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Telephone: 1-202-478-8858
Fax:       1-202-478-8821
Home: http://home.dtm.ciw.edu/users/boss/
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