Abstract
The equation of Casson (1957) and that of Goodeve (1939) have been presented for interpreting flow characteristics of disperse systems; the former particularly for suspensions and the latter for suspensions and emulsions. Although these two equations have been established on different theoretical models, they have similar forms in relating shear stress (or pressure) and rate of shear (or rate of flow), and they differ from each other only at a point where the equation of Casson has an additional term containing the square root of rate shear. From this formal difference the equation of Casson appears to have a wider applicability than that of Goodeve, especially in the range of greater rate of shear or in the range of smaller concentration of dispersed phase.
This consideration is examined in this paper by applying these two equations for experimental data obtained by the present author on the following systems: bentonite-water suspensions, benzenewater emulsions containing bentonite and oleic acid as emulsifiers, nitrobenzene-water emulsions containing amylalcohol and sodium dodecylsulfate as emulsifiers, and also for the data on blood obtained by Copley and his collaborators.
It is shown that the equation of Casson has certainly a wider applicability than that of Goodeve for both suspensions and emulsions, while the latter seems to have a favorable applicability for systems showing thixotropy and particularly for systems (emulsions) containing spherical particles.
