Dear lammps-users：
Recently , I am studying how to add a force related to velocity into my system , and I found that the fix viscous command could satisfy my requirement，but I do not understand the directivity of the force , does it with the same direction of velocity?
Thank you for your reply
Sincerely
Xuejiao Chen
Dear lammps-users：
Recently , I am studying how to add a force related to velocity into my
system , and I found that the fix viscous command could satisfy my
requirement，but I do not understand the directivity of the force , does it
with the same direction of velocity?
friction force is in the opposite direction of the velocity.
axel.