Powell-Eyring model

There are numerous other GNF models, such as the Casson model (used in food rheology), the Ellis, the Powell-Eyring model, and the Reiner-Pillippoff model. These are reviewed in the literature. In Appendix A we list the parameters of the Power Law, the Carreau, and the Cross constitutive equations for common polymers evaluated using oscillatory and capillary flow viscometry. 

FIGURE 10.22 Fanning friction factor versus Re measured in a once-through flow system with polyacrylamide (Separan AP-273) solutions. tp is the characteristic time calculated from the Powell-Eyring model. 

The Fanning friction factor/and the dimensionless heat transfer coefficient jH for the polyacrylamide 1000-wppm solution measured at an xId of 430 and at the Reynolds number equal to 20,000 [37] are presented in Fig. 10.33 as a function of hours of circulation. The dimensionless jH factor is seen to remain relatively constant at its minimum asymptotic value until some 3 hours have passed. On the other hand, the friction factor does not depart from its asymptotic value until some 30 hours of circulation have occurred. Estimates of the critical Weissenberg number based on the Powell-Eyring model yield values that are in good agreement with those given for the once-through system ... 

Powell-Eyring model (Eyring-Powell model) 779... 

Powell-Eyring model (Eyring-Powell model) n. A complex rheological equation containing three parameters that must be evaluated by fitting experimental flow data. It has the form ... 

Kincaid et al 1941) V toy J Tq = a characteristic stress (ii) theory of rate processes Empirical extension to the Powell-Eyring model... 

Upper Newtonian Viscosity n (poo) The coefflcient of viscosity of a fluid at very high shear rates, where Newtonian behavior is observed, although the fluid is non Newtonian at lower shear rates. This is often true for polymer melts that have chains that disentangle at shear rates above a critical shear rate. See, for example, Powell-Eyring Model. 

Another model of interest is given by Powell and Eyring (22),... 

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