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Why are the particles disappearing when I make the box virtual?

I’ve attached the simulation files. First, I fill the domain with particles and then activate the bond at 0.02 seconds. I’m also using another box to support the bonded particles. Why do the particles in the original box disappear after I make it virtual?

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EDEM

Accepted answers

Stephen Cole

Hi, it looks like the particles are falling out the domain due to gravity. The bonds haven't been created between particles.

I see that the bonded model isn't set at t=0 s rather it's added later, also the factory at t=0 s doesn't have the bond creation time set.

If you rewind the simulation to t=0 s and then apply the bond model to the particles, setting the bond properties. Also at t=0 s if you set the bond creation time - fixed - 0.02 s the bonds will be created between the particles.

Just to add I would expect a static factory type to be much faster in this scenario. Or if you use a dynamic factory make sure that the maximum number of particlse is equal to the amount that will fit into the domain. Currently the maximum is set quite high so when EDEM fills the domain with particles it will keep trying, and failing, to place more. But this is a very computationally expensive action and will slow the simulation down.

Regards

Stephen

All comments

Renan

Hi @RedRum,

After you make the original box a virtual geometry, you've actually removed the support (removed the "floor" of the simulation) of the particles, so they fall due to gravity.

Best regards,

Renan

RedRum

I am bonding the particles and retaining the leftmost two rows by introducing another physical box, which should make the entire group of particles hang like a cantilever. How can I confirm whether the particles are properly bonded? It's possible that the bonding isn't correct. Could you please check with the simulation files?

Renan

It seems that you're using a timestep of almost 100%. The bonding model requires a much smaller timestep, around 5% (sometimes less than that), in order to be stable. Also, it is best to have the bonding model from the start of the simulation and set the bond time, rather than adding it in the middle of the simulation

RedRum

Tried with 2%. Didn't work!

Stephen Cole

Hi, it looks like the particles are falling out the domain due to gravity. The bonds haven't been created between particles.

I see that the bonded model isn't set at t=0 s rather it's added later, also the factory at t=0 s doesn't have the bond creation time set.

Regards

Stephen