[Crib-list] SPEAKER: Jerry Wang (MIT) | CRIBB Seminar | Friday, Dec. 2, 2016 | TIME: 1:00 PM - 2:00 PM | Building 32, Room 141 (Stata)

[Shirley Entzminger]

 	COMPUTATIONAL RESEARCH in BOSTON and BEYOND SEMINAR


DATE:		FRIDAY, DECEMBER 2, 2016
TIME:		1:00 PM  2:00 PM
LOCATION:	Building 32, Room 141  (STATA)
 		(32 Vassar Street, Cambridge)

 		Pizza and beverages will be provided at 12:45 PM
 		outside Room 141.


TITLE:		Computational Modeling of Nanoconfined Fluids:
 		Big Surprises Come in (Very) Small Packages


SPEAKER:	JERRY WANG  (Massachusetts Institute of Technology)


ABSTRACT:

Nanoscale fluids, unlike their macroscale cousins, exhibit a number of 
surprising effects that are not present within continuum theories. In 
particular, the equilibrium and transport properties of nanoconfined 
fluids can be substantially different from the bulk properties of that 
fluid. Understanding the physical basis for these anomalous fluid 
properties including nanoconfined fluid structure, density, and 
self-diffusivity is central to many pursuits in nanoscale technology. 
These nanofluidic phenomena afford great opportunities to think big by 
thinking small specific engineering applications include nanoporous water 
filters to nanoscale drug delivery mechanisms to nanoscale heat transfer 
devices (as well as high-efficiency molecular simulation methods, for 
those of us who identify as computational engineers)!

In this talk, we present a theoretical and computational description of 
these phenomena in the context of dense simple fluids confined within a 
variety of nanoscale structures, including carbon nanotubes and graphene 
nanoslits. We show that the anomalous nanoconfined fluid density can be 
substantially lower than the bulk density, and that this reduced density 
is primarily due to repulsive fluid-solid interactions. Using a mean-field 
approach, we obtain closed-form analytical results for the length-scales 
associated with fluid layering near the solid-fluid interface. These 
results allow us to predict the equilibrium fluid density as a function of 
the confinement length-scale. Our predictions are in excellent agreement 
with molecular dynamics simulations as well as results from the 
experimental literature.

We also show that the fluid-solid energy landscape and associated density 
profile can be used to explain the anomalous diffusive transport observed 
in such systems. In particular, the presence of a layered structure near 
the fluid-solid interface implies that fluid molecules near the solid wall 
exhibit different dynamics as compared to bulk fluid molecules. By 
constructing different models for diffusion in the near-wall and the bulk 
regions of the CNT, we show that we can approximately predict the overall 
diffusive behavior of the nanoconfined fluid. We demonstrate that these 
results are in agreement with molecular dynamics simulations.  We show how 
several aspects of this theory can be used to model more-complex fluids, 
including water.  Finally, we demonstrate how accurate knowledge of these 
anomalous fluid properties can inform simple models of nanoscale mass and 
heat transfer phenomena.

==========================================

Massachusetts Institute of Technology
Cambridge, MA


For information about the COMPUTATIONAL RESEARCH in BOSTON 
and BEYOND Seminar, please visit...


 			http://math.mit.edu/crib/



===
Shirley A. Entzminger
Administrative Assistant II
Department of Mathematics
Massachusetts Institute of Technology
77 Massachusetts Avenue
Building 2, Room 350A
Cambridge, MA 02139
PHONE:	(617) 253-4347
FAX:	(617) 253-4358
E-mail:	daisymae at math.mit.edu


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