Experimental and numerical parametric analysis of a reoriented duct flow

Abstract

This study concerns a coupled experimental–numerical analysis of scalar transport in reoriented duct flows found in industrial mixing processes. To this end the study adopts the Rotated Arc Mixer (RAM) as the representative configuration. The focus is on the effects of geometrical (i.e. reorientation angle Θ) and temporal (i.e. reorientation frequency τ) parameters of generic inline mixing devices on the Lagrangian particle dynamics and scalar field evolution. Lagrangian dynamics are investigated by constructing Poincaré sections from analytic flow solutions and stroboscopic measurements of particle positions in 2D RAM laboratory setup. In order to obtain the optimal mixing and homogenization of scalar fields, dye visualizations are performed for an extensive set of parameters. The mixing quality in parameter space is quantitatively evaluated by means of the intensity of segregation. These results are used to determine the optimum forcing protocol. The outcome of this study validates the qualitative agreement in mixing characteristics of 2D time-periodic and 3D spatially-periodic flows and confirms the good mixing performance found before for certain RAM configurations. Moreover, we demonstrate that even more efficient protocols can be devised by suitably tuning the sequence of the reorientation angle. This knowledge might eventually lead to optimized 3D reoriented duct flow mixers.