Problem with Lees Edwards/Sllod for colloidal systems using Langevin dynamics


I have been trying to run Brownian Dynamics simulations by using fix/langevin and lj potential(in some cases r^-36 too). I am able to verify my results for the equilibrium dynamics but for shear flows my result donot match with those of Bergenholtz, Brady (2002). I tried using both methods ie just a fix/deform and also a fix/deform with SLLOD. One of the problems I was able to pinpoint was the velocity profile of my system. It is linear for most parts but there is an increase in slope on the boundaries (Plots atached). What could be the possible reason for this error.

I have 10,000 particles and have simulated volume fractions of 0.1,0.3,0.45 and see this as a consistent trend.

Thanks a lot.

velocity_profile.pdf (176 KB)

don't know - are you biasing fix langevin by the flow velocity,
or only applying it in the transverse directions?