Innovative Optimization of an Anchor Agitator With Convergent Notches for the Enhancement of Secondary Flows and Shear Stress Distribution in a Non-Newtonian Fluid

Abstract

Optimizing mixing systems is a key leverage point for improving fluid dynamics and energy efficiency in industrial processes. This study proposes an innovative approach aimed at enhancing the convergent notch within agitator geometries an original design that has not yet been explored in the literature. These geometric modifications are intended to improve agitator performance by promoting mixing while reducing energy consumption. This approach paves the way for more efficient mixing systems tailored to the needs of modern industries. The methodology is based on advanced numerical modeling, using the Ostwald–de Waele model to describe the flow of complex non-Newtonian fluids under laminar conditions. Modified agitator configurations incorporating a convergent notch of varying dimensions were compared with a standard design in a flat-bottomed stirred tank. To assess performance, key parameters were examined, including a flow behavior index ranging from 0.6 to 1.4 and a Reynolds number between 10 and 50. Energy-related results, expressed through the power number, along with tangential, radial, and axial velocity profiles and shear stress distributions, were used to thoroughly evaluate the impact of these modifications. The study revealed that varying the width of the convergent notches on the anchor led to a significant increase in radial flow, reaching an average of 50%, as well as a localized enhancement of axial flow, while maintaining the dominant tangential flow characteristic of standard anchor agitators. This synergy between the improved performance and the proposed design promotes more homogeneous mixing by expanding the effective flow region throughout the vessel, while also reducing both energy consumption and material volume around the notches. Compared to previous studies in the literature, which reported only limited gains in flow redistribution, the proposed configuration demonstrates a clear improvement in flow dynamics and better shear control. This innovative design offers an energy-efficient and high-performance solution for applications requiring gentle mixing and precise flow control, including polymers, emulsions, food, cosmetics, and pharmaceuticals.