[lammps-users] fix viscosity

LAMMPS LAMMPS Mailing List Mirror
1

Hi,

I am using fix viscosity command to try to obtain some information about the viscosity of a block copolymer melt. The simulation box is divided into 20 layers and the momentum flux is in y direction. However, no matter what Nswap and Nstep parameters I used, the velocity profiles, which are obtained through fix ave/spatial, indicating that only the 1st and 11th layers have a considerable velocity, whereas the velocity of the rest layers is close to zero. The initial velocities of all beads are random and I am running a DPD simulation. So may I have your opinion on this?
Thanks very much for your kind help.

Best Regards,

Weilong Zhao
from USTC

2

Have you visualized your system to see which atoms are
flowing? If only the 2 layers are flowing, then something
must be wrong with your pairwise interactions, or cutoffs,
or low density, etc.

Steve