Accession Number : ADA624424
Title : Llinas' Phase Reset Mechanism Delays the Onset of Chaos in Shark and Dolphin Wall Turbulence
Descriptive Note : Technical rept.
Corporate Author : NAVAL UNDERSEA WARFARE CENTER DIV NEWPORT RI
Personal Author(s) : Bandyopadhyay, Promode R ; Hellum, Aren M
Report Date : 10 Feb 2014
Pagination or Media Count : 55
Abstract : Turbulent boundary layers (TBLs) develop in the flow over planetary surfaces, over the bodies of swimming animals (like sharks and dolphins), and over the hulls of ships and submarines. Evidence points to organization in turbulence production, despite the apparent randomness and lack of a unified theory. Here, the dynamical systems of neuroscience are used to develop a self-regulation theory to show for the first time how the skins of sharks and dolphins control the chaos of turbulence. To remove the apparent randomness, the turbulence production cycles are split into pre- and post-breakdown regions, both during the organized laminar-to-turbulent transition and in the TBL, which is chaotic. Stuart-Landau oscillators describe the instabilities of the surface-normal diffusion of vorticity, which is coupled to the instabilities' span-wise diffusion. Similar to Llinas' olivo-cerebellar temporal phase reset mechanism, the shark and dolphin skins impose combinations of vorticity diffusion templates internal to the oscillators and external microvibration or flow oscillations, synchronizing the oscillators laterally and thereby eliminating chaos. The theory proving biological adaptation to environment has potential application to tornado path management. Shark and dolphin skins are major targets of reverse engineering mechanisms of drag and noise reduction.
Descriptors : *TURBULENT BOUNDARY LAYER , ADAPTATION , DOLPHINS(MAMMALS) , DRAG REDUCTION , FLOW , HULLS(STRUCTURES) , HYDRODYNAMICS , NOISE REDUCTION , OSCILLATORS , SHARKS
Subject Categories : Fluid Mechanics
Distribution Statement : APPROVED FOR PUBLIC RELEASE