Estimation of mean shear rate in a vessel of a planetary centrifugal mixer based on the heat balance equation

A planetary centrifugal mixer can fluidize highly viscous fluids in a vessel by strong centrifugal force. Although high rotation and revolution speeds are effective for particle dispersion, experimental observation and numerical simulation of the fluid flow in a moving vessel with a gas-liquid interface have not been well studied. Therefore, we propose the methodology to estimate a shear rate, which dominates the particle dispersion, by the temperature measurement. We measured the fluid and gas temperatures during mixing and used the heat balance equation to estimate the viscous dissipation rate, providing the mean shear rate. As a result, the effect of the mixing conditions on the mean shear rate has been clarified. Furthermore, the ratio of centrifugal force to viscous force helps identify the viscous dominant region, where not only a considerable rotation speed of the vessel but also a large revolution radius is helpful to increase the shear rate.