Van de Vusse, J.G., 1955, Mixing by Agitation of Miscible Liquids, Chem. W., 1988, Blending of Liquids of Different Viscosity, Chem. and Britter, R.E., 1985, Mixing Times for passive Tracers in Stirred Vessels, 5th Eur. and Pandit, A.B., 1988, The Mixing of Newtonian Liquids with Large Density and Viscosity Differences, 6th Eur. and Nienow, A.W., 1985, Mixing in theProcess Industries,Butterworths. A., 1990, The Influence of Viscosity and Density Differences on Mixing Times in Stirred Vessels.,Fluid Mixing IV.ĭanckwerts, P.V., 1951, The Definition and Measurement of some Characteristics of Mixing, Appl. and Cognet, G., 1985, Measurement of Coupled Velocity and Concentration Fluctuations in the Discharge Flow of a Rushton Turbine in a Stirred Tank, Chem. I., 1985, Mixing of stratified liquids, Chem. This process is experimental and the keywords may be updated as the learning algorithm improves.Īhmad, S. These keywords were added by machine and not by the authors. A critical Reynolds number, which depends on the viscosity ratio of the two fluids, has been proposed as the criterion for the operating conditions under which the mixing rate is extremely slow and the mixing time is much longer than that required for mixing fluids with similar properties. Preliminary studies of the mixing of non-Newtonian fluids showed the difficulty in determining an apparent viscosity at the strain rate actually experienced by the added fluid.ĭimensional analysis has been used to interpret these mixing time results in terms of the magnitude of the bulk inertia forces relative to the initial buoyancy forces and to viscous forces within the added fluid.

The mixing time was determined experimentally from the concentration time-history of tracer fluid using conductivity microprobes. Stirred tanks have commonly been used to perform such batch mixing processes but they are not always the most effective devices.Įxperimental studies were carried out to determine the conditions under which a viscous and dense fluid would be easily mixed into a low viscosity bulk, in fully turbulent flow (in all cases, the length scale of the viscous addition was larger than the integral velocity length scale for the flow, so that the bulk fluid appeared fully turbulent to the added material). Differences in viscosity between the added and the bulk fluid cause a reduction in the strain rate experienced by the more viscous fluid furthermore, large viscosities damp the inertial effects which would cause entrainment and mixing. The mixing of miscible fluids with significant density differences, but with similar viscosities, may lead to stratification, in which case buoyancy effects must be overcome to achieve a homogeneous mixture.

A high viscosity liquid will