Hi,
I am recently focusing on a particle cube system with a constant confining pressure, e.g. 50kPa. In my first code, I only use LIGGGHTS to exert this confining pressure and obtained the target pressure and void ratio. Then I write a restart file so that to restart the results in a CFDEM coupling procedure.
However, when I applied the restart file into a CFDEM procedure (the sample just be immersed in the hydrostatic water), I found the void ratio of my sample decrease sharply at a very instant time. I cannot figure out why this could happen.
Has anyone ever met a similar problem, i.e. From pure DEM to CFDEM code, the arrangement of particles will change so fast, from a relative loose sample to a denser one?
Many thanks.
Rachel
alice | Mon, 01/15/2018 - 07:04
Hello Rachel,
Hello Rachel,
it's a litte hard to tell but an instant decrease of the void ratio could indicate that the simulation diverges. (What about e.g. kinetic energy, and did you have a look at the residuals?). Generally what you describe should work, but make sure that the time stepping is chosen appropriately (ts for CFD and DEM, coupling interval size, ...) and that the boudary conditions are fine in both cases.
Best,
Alice