#complexphysics

[nakedfluiddynamics-blog]

“Turbulence is the most important unsolved problem of classical physics” said Feynman and remain an active field of current research. In a recent study Cardesa et al. made tremendous progress in observing the way turbulence works. The main theory of turbulence was proposed by the Russian mathematician and physicist Andrei Kolmogorov in the early 1940s. In his picture the energy spreads from large swirls to smaller eddies nearby till reaching a critical scale at which the viscous effects become important and dissipate the energy in heat. This “cascade of energy” explains how even low viscosity fluid like gazes (air) are able to dissipate rapidly energy. Onsager (one of the geniuses of the 1940s that even Feynman found intimidating to talk to) announced in 1949 that even in the absence of viscosity a fluid could in certain cases dissipates energy through turbulence: “a shocking idea” that was proven right mathematically in a recent paper of Isett (2016) but in a rather unrealistic flow (a more realistic case was proposed by Buckmaster et al. in 2017). The picture shows a drawing of Leonardo da Vinci on the movement of water showing with astonishing details the turbulent structures, the swirls and eddies. Sources: Castelvecchi, Mysteries of turbulence unravelled, Nature Comm. 548 (2017) Cardesa, Vela-Martin, Jimenez, The turbulence cascade in five dimensions, Science, 2017 Isett, A proof of Onsager’s conjecture (2016) https://arxiv.org/abs/1608.08301 Source image: image extracted from Lavin, Leonardo’s watery chaos (1993) #nakedfluiddynamics #fluiddynamics #fluidmechanics #physics #physique #scienceisart #science #artinscience #fluidartgallery #beautiful #picoftheday #awesome #turbulence #complex #complexphysics #chaos “When I meet God, I am going to ask him two questions: Why relativity ? And why turbulence ? I really believe he will have an answer for the first.” said Heisenberg.