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Department of Chemical Engineering
University of Michigan
Abstract-
Polymeric solutions exhibit startling flow phenomena, including
zero-inertia elastic instabilities and zero-inertia "turbulence." The
source of these
phenomena is in the entropic elasticity, hydrodynamic drag forces, and
Brownian forces exerted on the polymer molecule by solvent.
Molecular simulations combined with single-molecule experiments with DNA (esp.
those of Chu and coworkers) now allowed these forces to be determined
in detail. Images of fluorescing, DNA molecules released
in a crossed-channel geometry are compared
with Monte Carlo and Brownian dynamics simulations that account for the
molecule's entropic elasticity, Brownian motion, and hydrodynamic drag. The
simulated and observed molecules show a
wide variety of modes, including "dumbbells," "kinks," and "folds,"
the existence of which explains the peculiar flow properties of polymer
solutions.
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