Abstract
The mixing of inelastic Newtonian fluids was experimentally and numerically investigated by using eccentric impellers in stirred tanks. Two different scenarios based on single and dual off-centered impellers were proposed and compared to the standard steady-stirring configuration. Mixing times were experimentally measured by means of a color-discoloration technique based of a fast acid-base reaction, which allowed also revealing the formation of well-mixed zones (pseudocaverns) as well as segregated regions. The finite element method was used for modeling the mixing tank with the centered impeller, which a virtual finite element method with unstructured grids was used for the modeling the laminar flow when eccentric impellers are used. The latter method allowed modeling the flow reducing considerably the processing time compared to the traditional simulation method. Results obtained from this work show that if the operating conditions are properly set, mixing times can be drastically reduced compared to those obtained under the standard configuration, especially for high viscosity fluids.
