Four models for the material property inhomogeneities are presented in this paper. Three of these models admit analytical expressions for the relationship between pressure gradient and volumetric flow rate, but presume a piecewise constant particle concentration. The fourth model presumes a smooth relationship between the volume fraction and the shear rate, but requires a numerical solution. Results are presented in terms of the ratio of pressure gradients that can be produced by applying and removing the field.
Experimental data collected for a variety of quasi-steady ER flows shows that the analytical solution corresponding to a flow of uniform particle concentration provides an upper bound to the pressure gradients. Each of the four models for inhomogeneous flow provides a lower bound over a sub-domain of the flow conditions. By combining these models heuristically, a single expression for the lower bound on the pressure gradients of ER and MR flows is presented. (C) 1997 Elsevier Science B.V.
electrorheological, magnetorheological, inertial lift, image forces, phase separation, Bingham
ELECTRORHEOLOGICAL FLUIDS, PHASE-SEPARATION, SHEAR-FLOW, SUSPENSIONS, BEHAVIOR, SPHERE, FIELD, LIFT
Gavin HP, DUKE UNIV,DEPT CIVIL & ENVIRONM ENGN,DURHAM,NC 27708
ELSEVIER SCIENCE BV, AMSTERDAM