Mixing in microchannel patterned with superhydrophobic surfaces
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Date
2018-05
Authors
Yap, Eng Sam
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Abstract
Generally, microchannels can be defined as channels having dimensions in the range
of 1 µm to 1mm. The fluid flow will exhibit behaviors similar to macroscopic flows
when it flows in channels of dimension more than 1mm. The flow through a
microchannel network of a lab-on-a-chip device is diffusion dominant and is laminar.
Mixing in microchannel cannot be carried out by exciting the liquid streams in turbulent
flow to enhance its mixing performance because the Reynolds number (Re) is typically
below the critical value where transition to turbulence would occur. Thus, it becomes a
challenging problem for passive micromixers to mix fluids of different species within
the desired range of mixing channel length in the absence of enhanced mixing
techniques.
In microfluidic applications, efficient mixing has been understood as one of the most
fundamental and difficult-to-achieve issue. The study of mixing of fluids in
microchannel laminated with superhydrophobic surface is important because there is
an industrial desire to reduce the channel length and time needed for mixing of fluids
for the beneficiary, especially in biomedical applications. T-type mixer is employed
throughout the study and simulations show that effective mixing length increases with
the fluid speed, depicted by Re number.
In order to obtain efficient mixing of fluids in short residence times and mixing length,
contact area for the churning of higher and lower species concentrations needs to be
highly increased. Computational fluid dynamics simulations are used to determine the
mixing of fluids for various microchannel designs and operating conditions during this
study.