I’m doing a friction simulation and I want to reduce bouncing in my tip by applying some damping to it’s motion. I’m using the following fixes to the tip:
fix 1 topfix viscous 0.01
fix 2 topfix setforce 0.0 0.0 NULL
fix 3 topfix aveforce NULL NULL -0.05
If I run using this series of fixes, my force starts at -0.05 / atom then drops to zero with small oscillations. Basically it is damped like I want but with the wrong average force. If I run with the fix viscous off, it has large oscillations around -0.05 / atom.
I think what I want is Fatom = Fave - velgamma so I get a constant, nonzero applied force. What I am getting appears to be F = -velgamma only. Is there a way to get around this?