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TURBULENCE
In 1932 physicist Sir Horace Lamb said: "I am an old man now, and when I die and go to heaven there are two matters on which I hope for enlightenment. One is quantum electrodynamics, and the other is the turbulent motion of fluids. And about the former I am rather optimistic." He died two years later.
Thirty years later Richard Feynman, one of the greatest physicists of the 20th Century, said: "Turbulence is the most important unsolved problem of classical physics." By "classical" he meant physics as known to Victorians in the 19th Century before relativity and quantum physics revolutionized our thinking. Feynman received a share of the 1965 Nobel Prize for solving quantum electrodynamics.
When a fluid is slow moving, its motion is smooth and regular, called laminar, but above a certain speed it rapidly changes to turbulent, with parts having random motions in space. Whorls within twisted whorls, eddies within eddies. The sudden change is characterized by a "Reynolds number" which depends on sizes and the viscosity or "stickiness" of the fluid. Is it water or honey? Turbulence affects blood flowing through arteries, airplanes at high altitude, and cruise ships through the ocean. Many different and important situations, but turbulence is complicated, chaotic, and seemingly unpredictable.
Meanwhile, pay attention to the beauty of the smoke as it rises from a candle flame in still air. |