5 662 the viscosity vanishes and hence fully rough

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Unformatted text preview: on factor increases by 9 times as the roughness increases by a factor of 5000. In the transitional-roughness region, sand grains behave somewhat differently from commercially rough pipes, so Fig. 6.12b has now been replaced by the Moody chart. The Moody Chart In 1939 to cover the transitionally rough range, Colebrook [9] combined the smoothwall [Eq. (6.54)] and fully rough [Eq. (6.63)] relations into a clever interpolation formula 1 f 1/2 2.0 log /d 3.7 2.51 Red f 1/2 (6.64) This is the accepted design formula for turbulent friction. It was plotted in 1944 by Moody [8] into what is now called the Moody chart for pipe friction (Fig. 6.13). The Moody chart is probably the most famous and useful figure in fluid mechanics. It is accurate to 15 percent for design calculations over the full range shown in Fig. 6.13. It can be used for circular and noncircular (Sec. 6.6) pipe flows and for open-channel flows (Chap. 10). The data can even be adapted as an approximation to boundary-layer flows (Chap. 7). Equation (6.64) is cumbersome to evaluate...
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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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