Physical Modeling of the Effect of Shearing on the Concentration Profile in a Shear Cell

Abstract

The effect of the action of shearing a column of molten gallium (Ga) doped germanium (Ge) on the gallium concentration field in a shear cell segment was experimentally investigated using a physical model. A physical model is an experimental system that is different from the system of interest but connected by scaling relations. Water was used as the fluid in the physical model in place of the molten germanium, and methylene blue dye was used as a tracer in place of the gallium dopant to determine the extent of mixing. Two adjacent cylindrical fluid segments in a capillary of a shear cell were studied with the physical model. These fluid segment dimensions were scaled by a factor of seven for the physical model, since the kinematic viscosity of water at 22.6°C is seven times that of Ge at 950°C. A small amount of mixing between adjacent segments was measured due to the initial fluid‐fluid shear. The mass transfer between the top and bottom segments of the physical model during the fluid‐fluid shear was found to be less than 2% for all shear rates in the range 0.1–2.0 cm/s. The average mass transfer between adjacent segments due to the fluid‐fluid shear in that shearing range was 1.2%. © 1999 The Electrochemical Society. All rights reserved.