[lammps-users] create a flow/Velocity command

Dear lammps users,
I have a question about velocity command. I need to create a flow in my system.
If I use “velocity ID set 0.0 0.0 vz sum yes units box”, will this velocity be added to the molecule velocities at each step or this is just the initial velocity?
-if that is added every or a certain number of steps then, the velocity of the molecules will steadily increased. Is that right?
-if that is the initial velocity then, they will be rescaled by thermostat and then there will be no flow…

I will be appreciated if someone gives me a idea about this.
Thank you very much.


The velocity command is an initialization operation. See
fix addforce to add force every step which will result
in velocity.