The Inertio-Elastic Planar Entry Flow of Low-Viscosity Elastic Fluids in Micro-fabricated Geometries
Name
RoddEtAll.pdf
Description
Preprint submitted to J. Non-Newt. Fluid Mech.
Size
9.97 MB
Format
Adobe PDF
Checksum (MD5)
f1c667e1ab7cdd87e83f6db8cf4c131b
Author(s)
Rodd, Lucy E.
Scott, Timothy P.
Boger, David V.
Cooper-White, Justin J.
McKinley, Gareth H.
Date Issued
December 17, 2004
Series/Report no.
04-P-03;
Abstract
The non-Newtonian flow of dilute aqueous polyethylene oxide (PEO) solutions through
microfabricated planar abrupt contraction-expansions is investigated. The contraction
geometries are fabricated from a high-resolution chrome mask and cross-linked PDMS
gels using the tools of soft-lithography. The small length scales and high deformation
rates in the contraction throat lead to significant extensional flow effects even with dilute polymer solutions having time constants on the order of milliseconds. The dimensionless
extra pressure drop across the contraction increases by more than 200% and is
accompanied by significant upstream vortex growth. Streak photography and videomicroscopy
using epifluorescent particles shows that the flow ultimately becomes
unstable and three-dimensional. The moderate Reynolds numbers (0.03 ≤ Re ≤ 44)
associated with these high Deborah number (0 ≤ De ≤ 600) microfluidic flows results in
the exploration of new regions of the Re-De parameter space in which the effects of both
elasticity and inertia can be observed. Understanding such interactions will be
increasingly important in microfluidic applications involving complex fluids and can best
be interpreted in terms of the elasticity number, El = De/Re, which is independent of the
flow kinematics and depends only on the fluid rheology and the characteristic size of the
device.
Subjects
viscoelasticity
microfluidics
complex flow
abrupt contraction
Persistent DSpace Link
