what causes an agglomerate to fragment?

Fatemeh Hosseini_22198

Hello everyone,
In the CFD-DEM simulation, I had a big agglomerate containing 900 primary particles.
During the simulation, it breaks into two different agglomerates with 400 and 500 primary particles.
I know turbulence shear or colliding with other agglomerates/geometry may cause this fragmentation but I couldn't find any criteria in EDEM documents or help.
Does it depend on impact velocity or kinetic energy of collision?
if yes, where can I find these equations or formulas in EDEM documents?

Regards,
Fatemeh

Stefan Pantaleev_21979

Hi Fatemeh,

Particles in the agglomerate will separate if the forces trying to separate them are greater than the forces keeping them together.

The forces that separate particles could result from collisions and fluid drag forces among others.

The forces keeping particles together depend on the contact model and could be van der Waals type forces (JKR model, EEPA model) and solid bridge forces (bond model) among others.The magnitude of these forces depends on the respective model parameters (surface energy for JKR model, surface energy and pull-off force for EEPA model and bond critical shear and normal stress for the bond model). You could generally have anything from weak and brittle agglomerates to complete;y unbreakable agglomerates depending on the contact model and its parameters.

JKR model: https://help.altair.com/edem/Creator/Physics/Base_Models/Hertz-Mindlin_with_JKR.htm

EEPA model: https://help.altair.com/edem/Creator/Physics/Base_Models/Edinburgh_Elasto-Plastic_Adhesion_Model_(EEPA).htm

Bond model: https://help.altair.com/edem/Creator/Physics/Additional_Models/Bonding_V2.htm

Best regards,

Stefan