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Fluid Dynamics Seminar

Monday, March 5, 2007, 4:00 PM
Cullimore Lecture Hall, Room 611
New Jersey Institute of Technology

Spontaneous absorption of droplets into single pores and fibrous porous materials

Gerardo Callegari

TRI, Princeton University

Abstract

As a first part, droplet penetration into wetting capillaries of different size is revisited from a theoretical and experimental point of view. For fast absorption of Newtonian and Non Newtonian liquids, a characteristic constant velocity is experimentally found. Consistently with Bossanquet's description for Newtonian liquids, the velocity of the interface decreases with the radius of the capillary tube. For visco-elastic liquids, we experimentally found that the velocity presents a non-monotonic behavior with the capillary radius, revealing an optimum pore size depending on the visco-elastic properties of the liquid. This new experimental result is interpreted under a Maxwellian description of the fluid flow and open promising applications in the design of micro-bio-fluidic devices as well as in micro-rheology and absorption of droplets into porous materials. As a second part, different experimental results in droplet absorption into thin and thick fibrous materials are presented. Different possible scenarios are discussed and theoretically described.