Daily observations: (1) raindrops splashing on the glossy leaves of certain plants, (2) globules of oil spattering out from a hot frying pan.
How a droplet behaves depends on both its internal attributes (such as viscosity, mass, or velocity) and its external attributes (primarily, the surface on which it will eventually contact).
The dynamics between solid surfaces and discrete volumes of liquid is an increasingly growing subject of study, with applications ranging from printing and painting to even drug and computer chip manufacturing. (1) the splashing limit at high velocity impact, (2) the formation of a ring structure around the splat, (3) the dynamics of impact at short times, (4) the maximum spreading before an eventual recoil, (5) capillary waves at low velocity impact, (6) the influence on the contact-line arrest of dynamic surface tension, (7) non-isothermal drop deposition.
On a regular, non-hydrophobic surface, a drop of water will always demonstrate wetting behavior. Because the attraction between water molecules and surface molecules is normally greater than the attractions between adjacent water molecules, a water drop will tend to spread out (or wet the surface) in order to increase the interfacial area and thus, decrease the energy of the system. On a hydrophobic substrate, however, the opposite behavior will occur; instead of wetting the surface, a drop will try to decrease the interfacial area between solid and liquid as much as possible by maintaining an almost perfectly spherical shape.
Shear-thinning, in the world of fluid dynamics, is the behavior of a certain class of fluids, like ketchup and, more importantly, blood, that become runnier and less viscous as they flow in response to an applied force.
Non-Newtonian fluids are those whose viscosity does change under a shear stress. The behavior of such fluids (and of Newtonian fluids as well) may depend also on whether other stresses include heating or cooling and on how long a stress is applied. The apparent viscosity of ketchup, for example, decreases with the duration of the stress--the harder and longer you pound on the bottom of the bottle, the more likely a spurt of runny ketchup will be your reward. Such fluids are classified as "shear-thinning" fluids.
Comments
The 2006 François Naftali Frenkiel Award for Fluid Mechanics
Announcement: The 2006 François Naftali Frenkiel Award for Fluid Mechanics
Phys. Fluids 19, 010201
The recipients of the 23rd François Naftali Frenkiel Award for Fluid Mechanics are Jan Skotheim and L. Mahadevan for their paper:
Soft lubrication: The elastohydrodynamics of nonconforming and conforming contacts
Physics of Fluids, Vol. 17, 092101 (2005)
Professor Mahadevan
L. Mahadevan
http://www.seas.harvard.edu/softmat/
Harvard University
Applications of Mathematics to problems in Materials, Biological and Geological Sciences.
An energy balance approach of the dynamics of drop impact on a s
P. Attané, F. Girard, and V. Morin
An energy balance approach of the dynamics of drop impact on a solid surface
012101
Liquid drop impact against a solid surface
Daily observations:
(1) raindrops splashing on the glossy leaves of certain plants,
(2) globules of oil spattering out from a hot frying pan.
How a droplet behaves depends on both its internal attributes (such as viscosity, mass, or velocity) and its external attributes (primarily, the surface on which it will eventually contact).
The dynamics between solid surfaces and discrete volumes of liquid is an increasingly growing subject of study, with applications ranging from printing and painting to even drug and computer chip manufacturing.
(1) the splashing limit at high velocity impact,
(2) the formation of a ring structure around the splat,
(3) the dynamics of impact at short times,
(4) the maximum spreading before an eventual recoil,
(5) capillary waves at low velocity impact,
(6) the influence on the contact-line arrest of dynamic surface tension,
(7) non-isothermal drop deposition.
On a regular, non-hydrophobic surface, a drop of water will always demonstrate wetting behavior. Because the attraction between water molecules and surface molecules is normally greater than the attractions between adjacent water molecules, a water drop will tend to spread out (or wet the surface) in order to increase the interfacial area and thus, decrease the energy of the system. On a hydrophobic substrate, however, the opposite behavior will occur; instead of wetting the surface, a drop will try to decrease the interfacial area between solid and liquid as much as possible by maintaining an almost perfectly spherical shape.
Stationary coaxial electrified jet of a dielectric liquid surrou
F. J. Higuera
Stationary coaxial electrified jet of a dielectric liquid surrounded by a conductive liquid
012102
Dynamic wetting of shear thinning fluids
G. K. Seevaratnam, Y. Suo, E. Ramé, L. M. Walker, and S. Garoff
Dynamic wetting of shear thinning fluids
012103
Professor Garoff
Stephen Garoff
http://www.phys.cmu.edu/people/faculty/garoff/
Carnegie Mellon University
fluids subjected to shear stress, shear thinning
Shear-thinning, in the world of fluid dynamics, is the behavior of a certain class of fluids, like ketchup and, more importantly, blood, that become runnier and less viscous as they flow in response to an applied force.
Non-Newtonian fluids are those whose viscosity does change under a shear stress. The behavior of such fluids (and of Newtonian fluids as well) may depend also on whether other stresses include heating or cooling and on how long a stress is applied. The apparent viscosity of ketchup, for example, decreases with the duration of the stress--the harder and longer you pound on the bottom of the bottle, the more likely a spurt of runny ketchup will be your reward. Such fluids are classified as "shear-thinning" fluids.