The Electrostatics Model

Electrostatic forces can be included to existing kinematic forces by adding an Electrostatics model into the Particle Body Force section.

Electrostatic force is a force between particles exerted due to their charge, and can be either attractive or repulsive. Since the EDEM Electrostatic model uses Electrostatic screening, 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:  

 The screened Coulomb force Fs is defined as: 

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, λD. 

  •  qe 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.
  • Kb 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).

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