The application of existing theoretical models for
the computation of magnetic and hydraulic forces in a real
oriented matrix consisting of regularly arranged rods and
wires indicates that these models produce no exact results.
The differences between computations and measurements of
force effects documented by Maxwell lead to the conclusion
that it is necessary to start with different physical assumptions
when modelling a high–gradient separation process.
First of all, the magnetic field of the rods or wires system
differs from the magnetic field of a single rod. Second,
the particle need not be attracted to the rod surface, it is
brought there by the suspension stream and the magnetic force
must hold it, so that it is not entrained by the streaming
suspension. As the layer of attracted particles grows, the
magnetic attractive force on the surface of the growing layer
decreases until the magnetic attractive force is in equilibrium
with the entraining force of suspension flow.