Question: Calculation of relative velocity in EDEM.

Hi Yu,

During contact/collision different contact models can take different inputs, however typically (for example Hertz-Mindlin model) the Relative Velocity at the Contact Point is used to calculate the normal and tangential relative velocity of the elements and it does take into account the angular velocity of the particles.

You can see the source code for the Hertz-Mindlin model here - https://community.altair.com/community?id=kb_article_view&sysparm_article=KB0113635

Best regards,

Renan

Hi Yu,

 

During contact/collision different contact models can take different inputs, however typically (for example Hertz-Mindlin model) the Relative Velocity at the Contact Point is used to calculate the normal and tangential relative velocity of the elements and it does take into account the angular velocity of the particles.

 

You can see the source code for the Hertz-Mindlin model here - https://community.altair.com/community?id=kb_article_view&sysparm_article=KB0113635

 

Best regards,

Renan

Thank you for your answer. In this case, can I understand that the "relVel_t" of the H-M model in calculating the tangential damping force refers to the relative velocity, which takes into account the translation of particles and the resultant velocity of particles at the contact point due to rotation?

In this case, is the relative velocity calculated as follows?

Thank you very much for your answer!

Thank you for your answer. In this case, can I understand that the "relVel_t" of the H-M model in calculating the tangential damping force refers to the relative velocity, which takes into account the translation of particles and the resultant velocity of particles at the contact point due to rotation?

In this case, is the relative velocity calculated as follows?

Thank you very much for your answer!

The relative velocity (relVel in the HM model) takes into account both the translation and rotation of the particle at the contact point. It's calculate 171 of the model

// relative velocity of both surfaces at contact point CSimple3DVector relVel = element1.velocityAtContactPoint - element2.velocityAtContactPoint;

Then the relative velocity is split into two components: one in the normal direction:

 CSimple3DVector relVel_n = unitCPVect * unitCPVect.dot(relVel);

And one in the tangential direction:

CSimple3DVector relVel_t = relVel - relVel_n;

So the relVel_t in the tangential damping force calculation is actually the tangential component of the relative velocity.

Best regards,

Renan