Flow and Mixing in Rotating Zigzag Microchannel

The flow and mixing in rotating zigzag microchannel is investigated experimentally and numerically with objective of improving mixing, which is largely due to secondary or cross-flow in the cross-sectional plane of the channel and the bend connecting non-radial angled channel segments. Unlike the conventional stationary zigzag channel, crossflow in the zigzag channel is highly intensified from a combination of (a) centrifugal acceleration component in the cross-sectional plane due to the angled channel segments, (b) centrifugal acceleration generating Görtler vortices at “channel bends”, and (c) Coriolis acceleration. When the channel segment in the zigzag channel is inclined towards rotation direction (prograde), all three accelerations are aligned intensifying the crossflow; however, when it is inclined opposite to rotation (retrograde), Coriolis acceleration negates the other two accelerations reducing mixing. A numerical model has been developed accurately accounting for the interactions of throughflow, crossflow and material dispersion by diffusion and convection in a rotational platform. An experimental microfluidic platform with rotating zigzag microchannel has also been developed. Experimental results on mixing quality carried out at two rotation speeds compared well with prediction from the numerical model. The overall mixing quality of a rotating zigzag channel is much improved compared with that of a stationary zigzag channel.