Rolling stones and turbulent eddies: why the bigger live longer and travel farther.

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Here we report the discovery that even the simplest, oldest and most prevalent forms of evolutionary movement--rolling bodies and whirls of turbulence--exhibit the same body-size effect on life time and life travel as the evolutionary movement united by the body-size effect so far: animals, rivers, vehicles, jets and plumes. In short, the bigger should last longer and travel farther. For rolling bodies, the life span (t) and the life travel (L) should increase with the body mass (M) raised to the powers 1/6 and 1/3, respectively. The number of rolls during this movement is constant, independent of body size. For an eddy of turbulence, t should increase with the eddy mass (M) raised to the power 2/3, while L should increase with M(2/3) times the bulk speed of the turbulent stream that carries the eddy. The number of rolls during the eddy life span is a constant independent of eddy size.






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Bejan, Adrian (2016). Rolling stones and turbulent eddies: why the bigger live longer and travel farther. Sci Rep, 6. p. 21445. 10.1038/srep21445 Retrieved from

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Adrian Bejan

J.A. Jones Distinguished Professor of Mechanical Engineering

Professor Bejan was awarded the Benjamin Franklin Medal 2018 and the Humboldt Research Award 2019. His research covers engineering science and applied physics: thermodynamics, heat transfer, convection, design, and evolution in nature.

He is ranked among the top 0.01% of the most cited and impactful world scientists (and top 10 in Engineering world wide) in the 2019 citations impact database created by Stanford University’s John Ioannidis, in PLoS Biology.  He is the author of 30 books and 700 peer-referred articles. His h-index is 111 with 92,000 citations on Google Scholar. He received 18 honorary doctorates from universities in 11 countries.

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