  The particles of electrorheological fluids can be modelled as dielectric
spheres (DS) immersed in a continuum dielectric. When an external field is
applied, polarization charges are induced on the surfaces of the spheres and
can be represented as point dipoles placed in the centres of the spheres. When
the DSs are close to each other, the induced charge distributions are distorted
by the electric field of the neighbouring DSs. This is the origin of the
interaction potential between the DSs. The calculation of this energy is very
time consuming, therefore, the DS model cannot be used in molecular
simulations. In this paper, we show that the interaction between the point
dipoles appropriately approximates the interaction of DSs. The polarizable
point dipole model provides better results, but this model is not pair-wise
additive, so it is not that practical in particle simulations.
