UF Chemical Engineering > People > Faculty > Jason E. Butler
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Jason E. Butler
Ph.D., 1998, The University of Texas
at Austin |
| Associate Professor |
Ph : 352-392-2591
Fx: 352-392-9513
butler@che.ufl.edu
431 Chemical Engineering Building |
| Areas |
| Dynamics of Complex Fluids |
| Suspension and Multiphase Fluid Mechanics |
| Polymer Dynamics |
| Microfluidic Flows of Complex
Materials |
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| My research group studies dynamic phenomena within complex
fluids using experimental, computational, and theoretical
tools. Complex fluids, encompassing suspensions of particulates,
emulsions, and polymeric solutions and melts, serve important
roles in biotechnology, nanotechnology, materials science,
and emerging industrial technologies. Efficient control and
processing of these materials requires an understanding of
their transport properties, yet complex fluids often demonstrate
unexpected and intriguing behavior under flow. Some specific
examples from our studies are described. |
| Migration of macromolecules within microfluidic
devices |
| Keywords: Complex Fluids, Transport phenomena,
Biomolecular/Biomedical |
| Macromolecules flowing within a confined geometry experience
hydrodynamic and thermodynamic forces that can cause conformational
changes and net migration of the molecules. Recent simulations
and theoretical calculations demonstrated that the direction
and extent of migration depends upon multiple factors, which
can have important implications for the transport and control
of polymers in microfluidic devices. We are exploring possibilities
for using the phenomena for separations and other applications. |
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| Dynamics and rheology of nanorods and rigid
polymers |
| Keywords: Complex Fluids, Transport phenomena,
Nanosciences |
| Rigid polymers are widely used as high performance plastics
and examples of Brownian fibers can be found in the form of
macromolecules of biological origin and in nanotechnology
in the form of nanotubes and nanorods. Current work focuses
on eliminating the disparity between quantitative predictions
and measurements of the dynamic and rheological properties
of suspensions of Brownian rods and rigid polymers. This includes
resolving the scaling for the the long-time rotational diffusion
in semi-dilute suspensions and elucidating the mechanism for
shear thinning in suspensions in the limit of strong shear
and weak diffusion. |
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| Structure and rheology in oscillating suspensions
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| Keywords: Complex Fluids, Transport phenomena |
| Suspensions of non-colloidal spheres in non-uniform flows
can demix due to hydrodynamic interactions. For oscillatory
flows of suspensions within a tube, experiments indicate that
the particles migrate toward the wall under some conditions
and that there is sometimes a segregation of particles along
the pipe axis. We have explored the origin of this unexpected
behavior using rheological and simulations studies. Previously
unidentified phenomena resulting from the experiments and
modeling efforts have included the irreversibility of the
suspensions (as reflected by long-time changes in the rheology)
even at small amplitudes of oscillation and non-monotonic
viscosities which arise from underlying phase changes in the
microstructure. |
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| Instabilities in sedimentation of non-spherical
particles |
| Keywords: Complex Fluids, Transport phenomena |
| Mutual
hydrodynamic interactions among rigid rods sedimenting
in a viscous fluid create inhomogeneities in concentration
which, in turn, can enhance the mean sedimentation
rate beyond that measured in a dilute suspension.
This contrasts with sedimenting spheres, where increasing
concentration hinders the sedimentation rate. Continuing
work focuses on measuring the instability, refining
the models, and extending the concept to other particle
types. Improved models will aid design of separation
processes and understanding of natural sedimentation
processes. |
Rigid rods sedimenting in a viscous fluid |
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| Recent Publications |
| 1. |
Joontaek Park and Jason E. Butler,
"Inhomogeneous distribution of a rigid fibre undergoing
rectilinear flow between parallel walls at high Peclet
numbers," Journal of Fluid Mechanics, 630, 267-298,
2009. |
| 2. |
Jonathan M. Bricker, Hyun-Ok Park, and
Jason E. Butler, "Rheology of semi-dilute suspensions of
rigid polystyrene ellipsoids at high Peclet numbers,"
Journal of Rheology, 52, 941-955, 2008. |
| 3. |
Jason E. Butler, O. Berk Usta, Rahul
Kekre, and Anthony J.C. Ladd, "Kinetic theory of a
confined polymer driven by an external force and
pressure-driven flow," Physics of Fluids, 19, 113101,
2007. |
| 4. |
Bloen Metzger, Jason E. Butler, and
Elisabeth Guazzelli, "Experimental investigation of the
instability of a sedimenting suspension of fibers,"
Journal of Fluid Mechanics, 575, 307-332, 2007. |
| 5. |
O. Berk Usta, Jason E. Butler, and
Anthony J.C. Ladd, "Transverse migration of a confined
polymer driven by an external force," Physical Review
Letters, 98, 098301, 2007. |
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