Radiative+Transfer

=Radiation-Hydrodynamics=

This is a collection of questions and references for the radiative transfer discussion. We'll start with a quick taxonomy of radiation-hydro issues, then move on to these questions.

Questions

 * 1) Most people working in multiple dimensions are using flux-limited diffusion. How bad is it, and how do we check? For what types of problems is it OK, and for which do we need something better?
 * 2) For problems where we do need to do better, what sort of approach should we pursue? Should we try combining FLD with ray-tracing or Monte-Carlo, go to variable Eddington factor methods, or something else?
 * 3) Do we need to worry about operator-splitting radiation and hydro, or do we need to combine them without splitting to obtain high accuracy?
 * 4) Should we be focusing on mixed-frame or comoving-frame formulations of the radiation-hydro equations? Comoving-frame formulations are probably simpler in at least some types of codes, but by construction they cannot be conservative.
 * 5) Are there any problems in linking sink particles with radiative transfer, i.e. having sinks become "star particles"?

References (in no particular order):

 * [|Hayes et al, 2006, ApJS, 165, 188]: the ZEUS methodology paper, arguably the "standard" treatment of 3D radiation-hydro using a comoving-frame FLD method
 * [|Hayes & Norman, 2003, ApJS, 147, 197]: a variable Eddington factor method
 * [|Krumholz, Klein, & McKee, 2007, ApJ, 667, 626]: a mixed-frame formulation of FLD, along with discussion of some advantages of mixed-frame versus comoving-frame
 * [|Whitehouse & Bate, 2004, MNRAS, 353, 1078] and [|Whitehouse, Bate, & Monaghan, 2005, MNRAS, 364, 1367]: a pair of papers presenting a comoving-frame FLD approach with SPH
 * [|Miniati & Colella, 2007, JCP, 224, 519]: a discussion of how to avoid the loss of accuracy that comes from operator splitting between radiation and hydro
 * [|Krumholz & Stone, 2007, ApJ, in press], [|Whalen & Norman, 2006, ApJS, 162, 281], [|Abel, Norman, & Madau, 1999, ApJ, 523, 66]: three papers on ray-tracing ionization RHD and RMHD methods