Secondary flow Dean vortices

Moulin, P. Rouch, J.C. Serra, C. Clifton, M.J. Aptel, P. Mass transfer improvement by secondary flows Dean vortices in coiled tubular membranes. J. Membr. Sci. 1996, 114, 235-244. 

M 70a] [P 62] Computational flow simulation of the secondary flow, depicted by velocity vectors, was performed for Dean numbers of 10 and 100 [47]. The helical flow is weak for the smaller Dean number. The center of rotation is located close to the midpoint of the patch. For a Dean number of 100, a notable increase in the relative strength of the helical flow is observed the center of the vortex is shifted towards the outer channel wall. 

Fig. 7.7 Geometry of a staggered herringbone micromixer (left) and a curved channel to induce Dean Vortexes with corresponding secondary flow patterns (right). Arrow indicates flow [92].

The larger inertia of denser CTCs has also been used to isolate them on the microscale. MicroChannel structures such as herringbones can be used to induce secondary vortex flows which can promote movement of cells so that wall adhesion is promoted. Similarly, curved microchannels can induce Dean flows, which will laterally displace cells based upon their inertia. 

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