Comparative study of mixing performance in non-Newtonian Xanthan Gum solutions and water using various injection techniques in a cylindrical channel with vortex generators

The mixing performance of non-Newtonian fluids is critical in various industrial processes, directly impacting efficiency and product quality. This study investigates the mixing behavior of Xanthan Gum solutions, a widely used non-Newtonian fluid, compared to water using different injection techniques. Comprehensive flow visualization, wall shear stress measurements, pressure drop assessments, and mixing index evaluations were conducted within a cylindrical channel equipped with vortex generators. Results reveal that wall shear stress in Xanthan Gum solutions is significantly higher than in water and increases with rising Reynolds numbers. Additionally, Xanthan Gum solutions exhibit higher pressure drops and lower mixing index values due to their high viscosity and shear-thinning properties, which hinder mass transfer and diffusion. The central injection technique demonstrated superior mixing performance compared to lateral injection for both fluids. Notably, the mixing index for Xanthan Gum solutions stabilizes at Reynolds numbers of 500 and above, indicating that generated vortices do not alter the fluid's consistency. These findings align with the Herschel-Bulkley rheological model, characterizing the non-Newtonian behavior of Xanthan Gum solutions.