Viscosity
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In continuum mechanics, viscosity is a property of a fluid that quantifies the resistance force acting on fluids when there is relative motion between fluid parcels. This resistance force is caused by
Common logarithm of viscosity against temperature for B2O3, showing two regimes
In the University of Queensland pitch drop experiment, pitch has been dripping slowly through a funnel since 1927, at a rate of one drop roughly every decade. In this way the viscosity of pitch has been determined to be approximately 230 billion (2.3×1011) times that of water.
Honey being drizzled
Non-Newtonian fluid
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In physical chemistry and fluid mechanics, a non-Newtonian fluid is a fluid that does not follow Newton's law of viscosity; that is, it has variable viscosity dependent on stress. In particular, the v
Paint is a non-Newtonian fluid. A flat surface covered with white paint is oriented vertically (before taking the picture the flat surface was horizontal, placed on a table). The fluid starts dripping down the surface but, because of its non-Newtonian nature, it is subjected to stress due to the gravitational acceleration. Therefore, instead of slipping along the surface, it forms very large and very dense droplets with limited dripping.
Demonstration of a non-Newtonian fluid at Universum in Mexico City
Oobleck on a subwoofer. Applying force to oobleck, by sound waves in this case, makes the non-Newtonian fluid thicken.
Slime flows under low stresses but breaks under higher stresses