I've recently been messing around with the ol' Naviar-Strokes equations, creating a fluid simulator with the help of Mr. Jos Stam. I added vorticity confinement, which made for some really beautiful visual effects. I noticed these appeared similar to an accretion disk. I'd like to model an Accretion Disk in 2D first, obviously a particle based method isn't the best idea here, considering the scale. I'd assume that the proper method would be a scalar and vector field, but I'm unable to find any examples with the math behind it of a simulation of this type, and I'm unsure where to start. Google doesn't seem to be helping much, but I'm probably missing something in my search query. So, my question is, what methods would be good to simulate an accretion disk? I'd like to start with a uniform density and have it begin to collapse down and begin to swirl in a (somewhat) realistic manner.