Field-mediated hydraulic deformation and transport of magnetically solidified magnetizable particles

As an approach to conveying fluid entrained magnetizable particles, a uniform magnetic field is used to transform the particles into slugs having the nature of a deformable porous solid with internal stresses of magnetic origin. A biphasic model is developed for the design of hydraulic transport systems, relating the pressure drop to field induced shear stress between the slugs and the conduit wall, to the liquid volume rate of flow and to the solids rate of mass transport. Experiments are described that provide empirical parameters for the model. For 410 stainless steel particles (-35, +50 U S. sieve), Darcy's coefficient, found to be 1.0×10
⁷
kg/m
³
s, is essentially independent of field. The static Coulomb normal stress against the conduit wall is 15×10
³
N/m
²
at 5×10
^-2
T and zero at 10
^-2
T, varying essentially linearly with field. This normal stress is inferred from dynamic stress measurements as well. Hydraulically induced forces are used to show a phase transition from a fluidized state to a plastic solid at about 10
^-2
T and brittle fracture at higher fields at an angle that is essentially independent of field. Fracture is shown to be related to the same field induced internal stresses as determined the interactions with the conduit wall. It is suggested that the linear rather than quadratic dependence of these internal stresses on field are due to magnetic saturation at the points of contact between the particles.