Characteristic
energy transfer in a polymer-doped two-dimensional turbulent flow and
microfluidic approach to detect drag coefficients of polymers
Ruri Hidema,
Kobe University,
Japan
Abstract
Characteristic of complex fluids is scale
dependent nonlinear behavior. The dynamics of complex fluids in macro scale (~m
length scale) are very different from those in microscale (~mm length scale).
To clarify this interesting behavior, our group developed several experimental
works in mm – m length scale based on the idea of rheology and
fluid dynamics. My presentation will introduce recent and ongoing projects on
dynamics of polymer solution.
In the first part of my talk, I will discuss
characteristic vortex deformation and energy transfer caused by polymers in a
two-dimensional turbulent flow. The effects of the extensional rheological
properties of polyethylene oxide solutions were focused to understand the
vortex deformation in turbulent flow and turbulent statistics of the polymer
solution. In the polymer solution, although the turbulent energy production was
virtually zero, a characteristic peak appeared in turbulent energy. The results
imply the extension and relaxation of polymers affect the energy transfer.
In the second part, I will introduce a method to
measure the drag force due to synthetic polymers in flowing fluids by using a
scanning probe microscope. The conformation of polymers attached to the
cantilever probe was predicted, and the drag force due to the deformed polymers
in a flow was calculated. The drag forces obtained by model calculations were
compared to the force detected by experiments, and found to be reasonably
close.
[1] R. Hidema, K. Fukushima,
R. Yoshida, H. Suzuki, “Vortex deformation and turbulent energy of polymer solution
in a two-dimensional turbulent flow”, Journal of Non-Newtonian Fluid Mechanics,
285, 104385 (2020)
[2] R. Hidema,
S. Hayashi, Hiroshi Suzuki, “Drag force of polyethyleneglycol
in flow measured by a scanning probe microscope”, Physical Review Fluids, 4,
074201 (2019)
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