These are all great answers, thanks everyone. It is definitely more of a physics question than a programming one.
Ulf,
My objective is to determine the constant g in the offset between the bare friction and effective friction of the system in reference to the above paper (Alrichs and Dunweg 1999, and again in Usta et al 2005). The velocity of a particle under an external force was measured and I can only assume a terminal velocity was somehow determined.
Owen,
I think simulating flow between two plates could give the desired effect, as long as the system was large enough in the direction normal to the plates. I'm going to try it.
Stefan,
This is a very interesting point but I need to look into the implications of it to see if it satisfies the my problem. My hunch is that it does.
Best,
Vincent