Electrostatics

Electrostatic force is a force between particles exerted due to their charge, it can be either attractive or repulsive. Electrostatic forces can be included to existing kinematic forces by adding an Electrostatics model into the Particle Body Force section. EDEM Electrostatic model uses Electrostatic screening, therefore the size of a screen must be specified when using this model. Particles outside the screen will be removed from electrostatic force calculations on the central particle as shown below:

 

 

The screened Coulomb force F_s is given by

 

 

Where q₁ and q₂ are the charges of two particles, r is the distance between their centres, and ε₀ is the permittivity of free space (8.854 X 10^-12 Fm^-1). κ is an inverse of the Debye length, λ_D:

 

 

 

q_e is the charge of an electron (1.602 X 10^-19C)

ε is the relative permittivity of the medium. EDEM uses a value of 1, which is a relative permittivity of a vacuum.

K_b is the Boltzmann’s constant equal to 1.38 X 10^-23 JK^-1.

T is the temperature in Kelvin. EDEM uses a value of 295.4K.

The last term is the local charge concentration (where n is the number of particles of charge z).