Varnik F., Raabe D.
Max-Planck Institut fuer Eisenforschung, DE
Keywords: Chaotic mixing, flow at rough, lattice Boltzmann method
Lubricant flows are usually assumed to be laminar and the lubricated
metallic surfaces are anticipated to be perfectly flat and references therein). Both assumptions are incorrect
when it comes to a detailed analysis. Indeed, metallic surfaces are
never flat but reveal an average roughness ranging from some
nanometers to some micrometers depending on the mechanical and
microstructural boundary conditions. This applies in particular to
the evolution of surface roughness during elastic-plastic
deformation. This aspect has a strong influence on fluid dynamics at
such interfaces. In particular, near-surface fluid flow in the
vicinity of a metallic surface may become chaotic and unstable as
the surface roughness comes into play. This
roughness-induced chaotic flow is not necessarily identical to fully
developed turbulence. Nevertheless it exhibits strong
temporal and spatial fluctuations of the velocity field.
These findings are not only relevant for metal forming, but also
for all flow situations where the dimensions of “roughness elements”
(obstacles) are about 10% of the channel width or larger. In view
of increasing number of potential applications of chaotic flows
in civil engineering, environmental industry (e.g.
solution recovery) as well as in the medical science (e.g. enhanced
chaotic mixing in microchannels), the results of our studies may
find a wide range of applications as they open an alternative way
for tuning flow properties, namely via a clever design of
microchannels.
Journal: TechConnect Briefs
Volume: 2, Technical Proceedings of the 2006 NSTI Nanotechnology Conference and Trade Show, Volume 2
Published: May 7, 2006
Pages: 647 - 650
Industry sectors: Medical & Biotech | Sensors, MEMS, Electronics
Topic: Micro & Bio Fluidics, Lab-on-Chip
ISBN: 0-9767985-7-3