Flow curved channel mixing

The generation of secondary helical flows in suitably curved channels, known as Dean vortices, is not an entirely new fluidic phenomenon discovered at the micro scale actually it was found already also for wound tubings of conventional diameter (see a summary in [152]). In-depth studies concerning Dean vortices in curved channels were made in the framework of various applications such as filtration, heat exchange, friction and mixing. 

Jiang, F., Drese, K. S., Hardt, S., Kupper, M., Schonfeld, F., Helical flows and chaotic mixing in curved micro channels, AIChEJ. 2004, 50 (9), 2297-2305. 

Another way of increasing the mixing efficiency for Re in the range of a few hundred is the design of curved channels [28]. Here the mixing quality is improved by creating secondary flow pattern for Dean number (De) > 140, where... 

Dean flow as a static mixer The use of the fluid inertia across a curved channel can create turbulence. The flow of fluids in the meandering channels undergoes mixing due to the inertia of the fluid in the flow direction. An example is shown in Figure II.6, while the Dean number is defined in the side bar. 

Mixing by Helical Flows in Curved and Meander Micro Channels Most Relevant Citations... 

These stirring transverse flows can be generated by channel shapes that stretch, fold, break, and split the laminar flow over the cross-section of the channel. This effect can be achieved using 2D curved [111-113], or 3D convoluted channels [114—116] and by inserting obstacles [117] and bas-reliefs on the channel walls [54,118,119]. It must be noted that such type of chaotic flow could also be achieved by an active mixing strategy such as one using electrokinetic instability (EKl), as described in Sect. 3.2.2. 

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