I can do this:
velocity all set 0 0 0 units box
to set the linear velocity/momentum of all particles to zero initially after restarting a simulation. Is there a way to do that for the angular momentum (omegax, omegay, and omegaz) also? I don't think
velocity all zero angular
will do what I want. That just zeroes out the "aggregate" angular momentum.
You seem to be confusing aggregate momentum (linear or angular)
of a particle with that of a group of atoms. If you set the velocity
of a particle to 0.0 it will have no linear momenutm or angular momentum
(around any point). I presume what you want is for particles to
have velocity, but the net or aggretate momentum to be 0.0,
The velocity command can do this initially (for either linear or angular).
The fix momemtum command can adjust it on the fly (again for
either linear or angular), but you only need it if you are concerned that
you aren't conserving momentum for some reason.
Sorry, I should have been more clear. I really do want to set the individual linear/angular velocities of each particle initially to 0, not the aggregate of the whole group.
I am running a simple 2D granular chute flow to compare with Tom Drake's simulations and experiments (Drake & Walton, 1995, J. Appl. Mech.). As a test, I wanted to restart from an already-flowing simulation and set all the velocities to 0 to see if the flow would redevelop at different inclination angles.
I ended up using restart2data and then deleting the "Velocities" section of the data input file.