I have been wondering if it is logical to perform fix nve or fix nve/sphere on a pack of frictional grains? since in the case of friction energy can not be conserved and is lost in each collision. but all the sample input files that I have seen in the example directory of liggghts are integrated in with NVE.
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moritzhoefert | Mon, 03/05/2012 - 15:43
Please do not hesitate to
Please do not hesitate to correct me if I am wrong but doesn't fix nve apply a straight forward Verlet or Respa integrator? In that case the nomenclature is a bit "unfortunate". One should have called it fix updateVelocities instead.
If you apply a drag force, the system will of course loose energy. If you want to avoid that, you have to apply a thermostat like fix langevin.
ckloss | Tue, 03/06/2012 - 10:51
I agree with Moritz - if you
I agree with Moritz - if you use NVE and have no dissipation, i.e. coefficient of restitution is 1, energy will be conserved, otherwise not. NVE integration means that if you use non-dissipative interaction energy will be conserved
Cheers, Christoph
anandmds | Tue, 04/26/2016 - 12:44
Hey guys,
Hey guys,
I am getting a problem in understanding a concept. I am setting coefficient of restitution of a particle 1 (e = 1) and I let it freely fall in a container, and it starts bouncing perpetually.
but, I am getting different values of force exerted by the particle on the base of the container whenever it strikes the base of the container. This is not explained as there is no scope for any additional/loss of force.
Also, as e = 1, there is no normal damping component and tangential forces are completely absent. This leaves me to calculate the force exerted on the base (or by the base on the ball) as F = K_n*delta_n as per the formula given in the documentation. But I find that there is a considerable difference between the values that are dumped and the ones that I calculate using the formula.
Kindly please address these issues
Thanks & Regards
Anand