What's the criteria for positive and negative of force in API

Raheem Sterling_22160

Hi

I know the contact.force act on the contact point of particles, and then act on the element1 and element2 is opposite.

In HM model, I saw the equation is , but in the code, F_n = unitCPVect * -factor, and the F_t is as same as the equation.

For F_n, does it because the unitCPVect = contact.contactPoint - element1.position, and this direction is "-" in the EDEM?

 

Renan

Hi Raheem,

The equation you posted is used to calculate the magnitude of the normal force. Since forces are a vector quantity we also have to specify their direction and since the forces on the Hertz-Mindlin model are repulsive, they have to point in the direction such that the particles are separating, so the "-" sign in the equation is there just to make sure that the forces are actually repulsive.

Best regards,

Renan