Mixing enhancement in laminar flow using inclined inverted L-shaped vortex generators

This study presents a numerical investigation of the mixing performance and hydraulic behavior of a static mixer equipped with staggered inverted L-shaped vortex generators mounted on both the upper and lower walls of a rectangular channel, operating under laminar flow conditions. The working fluid is Newtonian with properties similar to water, and mixing is initiated by the introduction of two inlet streams with a step-change in concentration. The effects of Reynolds number (Re = 20-600) and vortex generators inclination angles (30?, 45?, 60?) on mixing efficiency and pressure drop are systematically evaluated. Results show that higher vortex generators inclination angles significantly enhance mixing at low to moderate Reynolds number due to stronger secondary flows and increased interfacial deformation. However, this improvement is accompanied by a notable rise in pressure drop. At higher Reynods number, the 30? configuration achieves a mixing index of 0.9468 with a pressure drop 78% lower than the 60? case, demonstrating a more favorable balance between mixing and energy consumption. The optimal configuration is found at a vortex generators inclination of 30? and Re = 600, offering efficient mixing with reduced hydraulic resistance.