Enhanced mixing by optimized streamwise and angular positioning of longitudinal vorticity

Streamwise vortices can be readily generated to enhance the mass and momentum transfer in continuous static mixers. The topology of these vortices is related to the shape and dimensions of the vortex generator (VG). It is essential to design the VG in such a way that the mass and momentum transfer are obtained for relatively small power dissipation. In the present paper, a streamwise and angular optimization study is performed for the passive scalar mixing enhancement downstream from rectangular wings inserted in a laminar circular pipe flow. The rectangular wing generates streamwise vortices which size is of the same order of the pipe radius. The optimal distance between two successive VGs is determined by analyzing the streamwise intensity of segregation and the pressure drop. The angular positioning of the vortices is also determined via local analysis of the scalar intensity of segregation. Such a study may be applied for other configurations of VGs where streamwise vorticity is used to enhance the mixing process in circular pipe flows.