Dear LAMMPS users,
I would like to use fix viscous in a granular simulation. However I'm not sure about gamma units.
gamma is specified in force/velocity units (SI [kg/s]).
With gamma = kT / m / D and D = kT / (6 pi eta d)
gamma = 6 pi eta d / m in 1/time units (SI [1/s]).
The Stokes drag force would be F = - 6 pi eta d / m * v.
I presume the definition gamma = kT / m / D is wrong and should read
gamma = kT / D.