SamplerBox

[Mohammad Wasfi]

Hello,

This is a DEME-related question.

Starting with the DEMdemo_BallDrop, I am trying to develop a similar code where I drop an object on a bed of particles. I started with changing the type of sampler from HCP to PD using the sampling method implemented in the DEMdemo_Repose. I have also reduced the domain size, particle size, and time step. I am running into two main problems. First, my bed is sampled in small prismatic sections as shown in the attached picture. I am trying to have one continuous box of particles and not sure what is causing this problem. Second, once I start the simulation, the particles scatter and fly up randomly as shown in the second attached picture. I am not sure what would cause that but I am assuming that the two problems might be related somehow. I attached my code for your reference.

Thank you so much in advance, 

 

[Ruochun Zhang]

Hi Mohammad,

This is because you SetCoordSysOrigin at "center", then your simulation domain is [-0.25, 0.25]³ (this is in one of the initialization info output lines). But your particle sample center is somewhere like X = 0.25, Y = 0.25, so most of the particles you sampled are out of this domain. DEME's coordinate system is periodic, so those out-of-domain particles may just appear to be in the domain on the other side, but it does not make this simulation work, due to huge initial penetrations against the side walls.

You can keep the system origin at "center", but the sample center needs to change accordingly.

Thank you,

Ruochun