Apparent viscosity

About: Apparent viscosity is a research topic. Over the lifetime, 5331 publications have been published within this topic receiving 114009 citations.

Mixture Law for Viscosity

Abstract: ARRHENIUS1 proposed the following expression for the viscosity of a solution : where ηs is the viscosity of the solution ; N1 and η1 are the mole fraction and the viscosity of component 1 ; N2 and η2 the mole fraction and the viscosity of component 2. However, both positive and negative deviations from this equation are found to occur. From a comparison of vapour pressures and viscosities of solutions, we deduced that in many cases the following equation yields closer agreement with experimental results : where d is a characteristic constant of the system. The accompanying graph shows curves calculated according to equations 1 and 2 (with d = -0·0224) for the system trans-decalin—cis-decalin. The points on the graph represent the experimental results of Bird and Daly2.

The viscosity of suspensions of rigid spheres

Abstract: An explanation is given of the dependence of the relative viscosity on the size distribution of the suspended spheres, an effect recently observed by Ward and Whitmore.(1) It is shown theoretically that if the spheres are of very diverse sizes, the relative viscosity is (1 - c)-2.5 for all values of the volume concentration c. For spheres of equal size, the validity of the Einstein expression for the relative viscosity (1 + 2.5c) is restricted to concentrations well below c = 0.05; while for medium and high concentrations the relative viscosity is given by the theoretical expression (1 - 1.35c)-2.5. The use of the latter formula in interpreting measurements on the viscosity of solutions is briefly indicated.

Agitation of non‐Newtonian fluids

Abstract: Since the shear rate of a non-Newtonian fluid is of importance in fixing the rheological or viscometric behavior of such a material, the present study has been concerned with the development of a general relationship between impeller speed and the shear rate of the fluid. The resulting relationship was then used to interpret and correlate power-consumption data on three non-Newtonian fluids by use of a generalized form of the conventional power-number–Reynolds-number plot for Newtonians. Flat-bladed turbines from 2 to 8 in. in diameter were used exclusively. Tank diameters ranged from 6 to 22 in. and power inputs from 0.5 to 176 hp./1,000 gal. The study encompassed a 130-fold range of Reynolds numbers in the laminar and transition regions. The results to date indicate that power requirements for the rapid mixing of non-Newtonian fluids are much greater than for comparable Newtonian materials.