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W. G. Pritchard Lab Seminar: 3:30 - 4:30 PM, 216 McAllister Bldg

	            **Monday September 11, 2006**
	
Hydrodynamics of complex fluids at small length-scales

Amy Q. Shen

Department of Mechanical Engineering
Washington University


Abstract:

Understanding fluid transport and interfacial phenomena of complex fluids 
at small length-scales is crucial to understanding how to design and 
exploit of micro- and nano-fluidic devices. I will present two examples. 
The first studies evaporation driven self-assembly to synthesize 
nanoporous thin films. A combination of experimental measurement and 
modeling using lubrication theory shows how self-assembly influences 
coating film thickness. The second example studies how length-scale and 
fluid elasticity affect droplet pinch-off of "simple" polymeric liquids in 
microfluidic environments. Boger fluids (viscoelastic liquids with nearly 
constant shear viscosity) are pumped into microchannels and pinched off to 
form droplets in an immiscible oil phase. We find a power law relation 
between the dimensionless capillary pinch-off time and the so-called 
elasticity number, E, of the fluid. Theoretical models that neglect the 
extensional viscosity of the fluid become increasingly more inaccurate as 
the fluid elasticity increases. 

		   *joint with PDE/Numerics seminar*

    NOTE SPECIAL TIME AND PLACE: Mon 3:30-4:30, 216 McAllister

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