Turbulence lecture 20

Turbulence lecture 20 - Turbulence Lecture 20 Us ( x) x =...

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Turbulence Lecture 20 () 1 2 0 1 2 1.58 0.252 s Ux x U x x  =  Θ  = ΘΘ A Once you know U (implies M ) then everything is known in the far field. 0 Θ The agreement isn’t bad, especially for 1.3 η < f y = A Inaccuracy for large is often attributed to intermittency of flow 2 Clear that x A is small in far field. 1 2 0 0.252 0.08 2 s U x x U == ∂Θ A Also find max 0.35 0.4 s u U uv uv ′′ (rms) If we assume that a constant value of v τ could represent turbulent diffusion. 1
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i.e) 2 0 2 UU v v Uu x yy τ ∂∂ ∂ =− = ∂∂ () [] 2 0 2 2 2 , , 1 1 exp 2 s s s sT xy U uv v y gU x v U U v U v gf x y U Uxy v f UR uv ττ ηη η −= −= − = =  ′′ ==    A 2 s uv U y = A Consider Turbulent KE equation Stationary 2 2 i u t 0 2 2 i u U x + 22 ii uu VW yz ++ 0 (1) L A 2
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22 ii uu pu u pv v xyz  ∂∂∂  =− + +   0 2 ij ij UUVV vu v v s xyxy µ ∂∂∂∂ +−−−− s () L A ( ) 1 ( ) L A ( ) 1 ( ) 2 L A ( ) L A 1 {} 2 ji j us xy z ∂∂ −− 0 1 Re L A 1 Re Dominant term is dissipation rate. 0 uv Up u + ±²³ ²´ ±²²³ ² ²´ u N U uv y ε
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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 20 - Turbulence Lecture 20 Us ( x) x =...

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