Turbulence lecture 17

Turbulence lecture 17 - Turbulence Lecture 17 i > 0 then...

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Turbulence Lecture 17 2 0 i j x ω  >   then 0 ij i j s ωω > and vortex tube stretching is dominant mechanism. Vortex stretching transfers vorticity (and energy) from large to small scales – where it is ultimately dissipated. It broadens the energy spectrum and feeds energy to small scales for dissipation. Free Shear Flows It is useful to distinguish 1. Flows that are influenced by boundaries, B. L. flow, channel, flow past object. 2. Free shear flows, mixing layers, jets, wakes. Rationale: 1. For high Re no’s, free shear flows, become independent of Re no., whereas for bounded flows – if you go close enough to boundary, then a Re which goes like 1 u R v A ∼∼ so it is not all Re no independent, and viscous effects are directly important. 2. Dynamics are different. a. Large source of vorticity at boundary. b. Streaks are produced near the boundary – peculiar to bounded flows, bursts, etc.
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This note was uploaded on 06/07/2011 for the course EGM 6341 taught by Professor Mei during the Spring '09 term at University of Florida.

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Turbulence lecture 17 - Turbulence Lecture 17 i > 0 then...

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