Non-linear viscous flow

The flow behavior is dilatant for n 1, Newtonian for = I and pseudoplastic for n . For these materials, the viscosity is still defined as the stress-strain rate ratio. In this way, viscosity becomes dependent on strain rate, i.e.. 

For small values of n (e.g., n 0.1), the behavior approaches an ideal pseudoplastic state, in which the strain rate becomes independent of stress (after reaching a yield stress). The idea of yielding is important for viscous media that contain attracting particles, because a finite stress is needed to initiate flow. 

Alternatively, particles may be initially in contact but become separated by a fluid at a higher stress. For media in which the yielding behavior is very abrupt, as shown in Fig. 5.8, Eq. (5.34) can be re-written as 

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Simmons, J.H, (1998) What is so exciting about non-linear viscous flow in glass, molecular dynamics simulations of brittle fracture and semiconductor-glass quantum composites. J. Noncryst. Solids, 239 1-15. 

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