Snowballs & Hot Jupiters

I want to set up a 1D grid of boxes containing dust and gas representing an accretion disk and then place a few seeds to grow into planets. The seeds have some random/PR mass which will suck up some of that neighboring dust and gas, moving around based on adsorbed mass and momentum. This would equal out, unless we randomly work out some fraction of the potential mass to be absorbed, which is what we will do. We do the square root of the PR and average it with a half to get some number between one quarter and three quarters, and tending towards about sixty percent. We can move about sixty percent of the seeds’ mass towards seeds in neighboring rings or boxes, based on mass and distance of course, and accrete about sixty percent of this same mass to the proto-planet in the same box or ring. I can run this with an animation loop, moving gas and dust like a sand simulation and having each seed snowball into planets of varying sizes.

This still doesn’t get me to hot Jupiters, just a solar system clone. I need to figure out how to model the migration of planets inward or outward, especially big ones which have no business forming close to their star...