Abstract (EN):
The flow of Newtonian and non-Newtonian fluids within microfluidic rectifiers with a hyperbolic
shape was investigated to assess the effect of the bounding walls on the diodicity of the microfluidic
device and achieve high flow anisotropy. Three microchannels were used, with different depths and
the same geometrical configuration, which creates a strong extensional flow and generates high
anisotropic flow resistance between the two flow directions. The Newtonian fluid, de-ionized water,
was used as a reference fluid. The viscoelastic fluid used was an aqueous solution of polyethylene
oxide (0.1% w/w) with high molecular weight. The flow patterns were visualized using streak
photography and the velocity field was investigated using micro-particle image velocimetry.
Moreover, pressure drop measurements were performed in order to compare the diodicity achieved in
the microfluidic rectifiers. For the Newtonian fluid flow, the experimental results are compared with
numerical predictions obtained using a finite-volume method and good agreement was found between
both approaches. For the viscoelastic fluid, significant anisotropic flow resistance can be achieved.
The effect of the bounding walls was analysed and found to be qualitatively similar for all
microchannels. Nevertheless, in quantitative terms, the diodicity is enhanced when the wall effect is
reduced, i.e. when the channels are deeper. A maximum diodicity above six was found for the deeper
channel, a value well beyond those previously reported
Idioma:
Inglês
Tipo (Avaliação Docente):
Científica
Nº de páginas:
10