Limitations to the Concept of Particulate Electrorheological Fluids

Perhaps the most problematic area that obstructs the control of these changes by the use of electrorheological fluids is the particle mechanics or continuum conundrum for characterizing the flow of the dense slurry (unexcited) or yielding plastic (excited). Whilst many years have been spent in computer analysis 

It is now evident that polarisation is not the only mechanism at work and that hydrodynamic effects [107] plus conductivity [96,108,109] at least need to be included in multi body effect models designed to illustrate the modus operand of the effect and to link it quantitatively to solid particle/ffuid properties, flow conditions and excitation levels (see Fig. 6.69). 

The possibilities of characterising ER fluids in flow as a continuum (otherwise the properties of viscosity and density have little significance and design 

The extended concentration by fluid developers on the details of slow steady flow belies the necessity to confront the intensely unsteady (and indeed steady) high shear-rate motions that will be required in practical machine work cycles. Very often misleading appraisals of situations arise from the lack of fluid/machine performance details. 

Referring to the ultra high acceleration/low-inertia flexible machine regime, it is predicted that the limiting change of (99%) speed response time to, in the digital mode of operation is heavily influenced by the inter-electrode gap size, and the fluid density and viscosity [103]. The solid part of the power transmission mode dominates the mechanics. 

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