PHYSICAL MATHEMATICS SEMINAR
 

TITLE:	HYDRODYNAMIC SLIP OF SIMPLE FLUIDS AT SOLID
	SURFACES:  WHEN ROUGHNESS DECREASES FRICTION



SPEAKER:	LYDERIC BOCQUET
		Laboratory of Condensed Matter Physics
		Universite de Lyon I, France


ABSTRACT: 

The no slip boundary condition at a solid surface is a standard assumption 
in hydrodynamics. However, it has been observed rather recently that a dense 
fluid can actually slip on a solid surface. Large slippage are usually associated 
with hydrophobic surfaces. In this talk we use simulation and theoretical results 
in order to interpret and rationalize such a behavior. However, on the experimental 
side, there is a strong debate in the literature about the amount of this slip effect. 
Results obtained by different groups, using various techniques, vary over a few 
orders of magnitude. In this context, we present both theoretical and simulation 
results showing that the concerted effect of wetting properties and surface 
roughness may considerably affect the slip. In particular we show that the 
slippage of the fluid at a solid boundary is found to drastically increase by using 
patterned surfaces.  Our results show that, in contrast to the common belief, 
surface friction may be reduced by surface roughness.



TUESDAY, DECEMBER 2, 2003, 2:30 pm, Building 2, Room 338

Refreshments will be served at 3:30 PM in Room 2-349

Massachusetts Institute of Technology, Department of Mathematics
Cambridge, MA  02139