Increase the timestep by increasing the particle density

Submitted by southeast1012 on Sun, 03/22/2020 - 07:56

Hi everyone
In some papers, the authors increasd the particle density a thousand times to increase the time step.
Can we do that in LIGGGHTS? Is there any paper refer to it?
Best regards

Forums:

tjleps | Mon, 03/23/2020 - 05:08

The maximum stable timestep is approximately proportional to the square root of the mass of the grains, so increasing the density can increase the maximum tilmestep, however it is up to you to determine if the change in mass will affect the fidelity of your model. Reducing the stiffness of grains is also a good strategy for increasing time step, though it will change the dynamics of your simulation. Again it is up to you to determine how much the stiffness can be reduced before your fidelity suffers too much.

See fix check/timestep/gran command for a simple way to check if your simulation is in the ballpark for the timestep. Doing a sensitivity analysis for your specific system is always a good idea as well.