Chapt06

Transition also occurs in external flows around

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Unformatted text preview: g transition from laminar to turbulent flow. Thereafter the force coefficient of a body was acknowledged to be a function of the Reynolds number [Eq. (5.2)]. There are now extensive theories and experiments of laminar-flow instability which explain why a flow changes to turbulence. Reference 5 is an advanced textbook on this subject. Laminar-flow theory is now well developed, and many solutions are known [2, 3], but there are no analyses which can simulate the fine-scale random fluctuations of turbulent flow.1 Therefore existing turbulent-flow theory is semiempirical, based upon dimensional analysis and physical reasoning; it is concerned with the mean flow properties only and the mean of the fluctuations, not their rapid variations. The turbulent-flow “theory” presented here in Chaps. 6 and 7 is unbelievably crude yet surprisingly effective. We shall attempt a rational approach which places turbulent-flow analysis on a firm physical basis. (b) (c) Fig. 6.5 Reynolds’ sketches of pipe-flow transition:...
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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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