"Air's a perfectly elastic fluid
," roars George above the tumult.
A bio-mechanical experiment carried out at the University Of Pennsylvania School Of Engineering and Applied Science has answered a long-standing theoretical question if microorganisms swim faster or slower in elastic fluids and the answer is "slower", the university website said
The report said some animals, microorganisms and cells move in a wave pattern and they often do so through elastic fluids. Movements of worms on aerated wet soil and sperm racing toward an egg are all due to this phenomena which deal with our everyday life.
"There have been qualitative observations of sperm cells, for example, where you put sperm in water and watch their tails, then put them in an elastic fluid and see how they swim differently," Arratia said in the University website.
Marcet's terms, such as "elemental bodies," "constituent parts" and "elastic fluids
" (gases) sound odd today, but she did use them very effectively to explain the phenomena she explored with her two curious students.
Two-dimensional (2-D) flow of elastic fluids in a steady lid-driven cavity was studied by Pakdel et al.
They also found that the torsionally driven cavity is a suitable geometry for testing the ability of non-Newtonian constitutive models to describe the behavior of elastic fluids in 3-D flows.
This suggests that elastic fluids
generate extra stress above the shear stress in the direction of the flow.
Static numerical simulations (water-based fluid flowing around an immobile oil droplet) showed that additional forces are present in the case of elastic fluids
. Dynamic simulations revealed striking differences in the behavior of elastic and inelastic fluids; oil droplets underwent deformation over time when inelastic fluids were injected, but the droplet did not deform in the presence of elastic fluids
The model of [v.sub.t] by (17) and (19) satisfies the following two assumptions: first, very small-scale eddies are damped by the elastic behavior of the fluid and thereby the eddy viscosity decreases ([v.sub.t] [right arrow] 0 when [t.sub.[eta]] << [lambda]); secondly, the eddy viscosity for less elastic fluid
is close to be that for the Newtonian case ([v.sub.t] [right arrow] (2) when [t.sub.[eta]] >> [lambda]).