De Wael

A common choice of functional relationship between shear viscosity and shear rate, that u.sually gives a good prediction for the shear thinning region in pseudoplastic fluids, is the power law model proposed by de Waele (1923) and Ostwald (1925). This model is written as the following equation... 

A useful two-parameter model is the power-law model, or Ostwald-de Waele law to identify its first proponents. The relation between shear stress and shear rare is given by ... 

A highly concentrated suspension of flocculated kaolin in water behaves as a pseudo-homogeneous fluid with shear-thinning characteristics which can be represented approximately by the Ostwald-de Waele power law, with an index of 0.15. It is found that, if air is injected into the suspension when in laminar flow, the pressure gradient may be reduced even though the flowrate of suspension is kept constant, Explain how this is possible in slug flow and estimate the possible reduction in pressure gradient for equal volumetric flowrates of suspension and air. 

De Waele, M., Renmans, W., Segers, E., De Valck, V., Jochmans, K., and van Camp, B. (1989) An immunogold-silver staining method for detection of cell surface antigens in cell smears. J. Histochem. Cytochem. 37, 1855-1862. 

De Waele, J. P., Audet, R. M., Leong, D. K. and Butterworth, R. F. Portacaval anastomosis induces region-selective alterations of the endogenous opioid system in the rat brain. Hepatology 24 895-901,1996. 

The study of bubble formation in non-Newtonian fluids has not been reported in literature in spite of the great industrial uses of these fluids. Recently, Subramaniyan and Kumar (S16) have studied bubble formation under constant flow conditions in fluids following the Ostwald-de-Waele rheological model. The model of Kumar and Kuloor (K16, K18, K19) has been extended to take into consideration the drag variation caused by the complexity of the rheological equation. 

The power law viscosity model was developed by Ostwald [28] and de Waele [29]. The model has been used in the previous sections of this chapter and it has the form shown in Eq. 3.66. The model works well for resins and processes where the shear rate range of interest is in the shear-thinning domain and the log(ri) is linear with the log (7 ). Standard linear regression analysis is often used to relate the log... 

Pappas PG Rotstein CME, Betts RE, Nucci M, Talwar D, De Waele JJ, Vazquez JA, Dupont BE, Horn DL, Ostrosky-Zeichner L, Reboli AC,... 

These liquids are known as Ostwald-de Waele Fluids. Figure 8 depicts a typical course of such a flow curve. 

Figure 8 Typical course of the flow curve of an Ostwald-de Waele fluid obeying the so-called power law behavior.

These liquids are known as Ostwald-de Waele fluids. Figure 5 depicts a typical course of such a flow curve. Figure 6 shows a dimensionless standardized material function of two pseudoplastic fluids often used in biotechnology. It proves that they behave similarly with respect to viscosity behavior under shear stress. 

A hypothesis has been published by de Waele [36] that nitrocotton combines with metallic oxides (pigments) through the carboxylic groups. The latter are present in partially oxidized derivatives of cellulose that accompany nitrocellulose. More recently Campbell and Johnson [37] have come to conclusions similar to those of Vodiakov and of de Waele. 

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