Chapt06

Downstream of x le the velocity profile is constant

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Unformatted text preview: is constant, the wall 1 | v v Reference 32 is a computer model of large-scale turbulent fluctuations. | e-Text Main Menu | Textbook Table of Contents | Study Guide 6.2 Internal versus External Viscous Flows Growing boundary layers Boundary layers merge Inviscid core flow 331 Developed velocity profile u (r ) r x u (r, x) Entrance length Le (developing profile region) Fully developed flow region Pressure Entrance pressure drop Fig. 6.6 Developing velocity profiles and pressure changes in the entrance of a duct flow. Linear pressure drop in fully developed flow region 0 x Le shear is constant, and the pressure drops linearly with x, for either laminar or turbulent flow. All these details are shown in Fig. 6.6. Dimensional analysis shows that the Reynolds number is the only parameter affecting entrance length. If Q Le f(d, V, , ) V A Le d then g Vd g(Re) (6.4) For laminar flow [2, 3], the accepted correlation is Le d 0.06 Re laminar (6.5) The maximum laminar entrance length, at Red,crit 2300, is Le...
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This note was uploaded on 10/27/2009 for the course MAE 101a taught by Professor Sakar during the Spring '08 term at UCSD.

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