Viscous Flow in Pipes.pdf
Viscous Flow in Pipes.pdf
Viscous Flow in Pipes.pdf
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Integral Analysis for Increased Pressure Drop <strong>in</strong> theEntrance Region(From S.R. Turns, Thermal-Fluid Sciences, Cambridge Univ. Press, 2006)The <strong>in</strong>creased pressure drop <strong>in</strong> the entrance region result from tworeasons: 1. flow acceleration, 2. <strong>in</strong>creased wall shear stress.1. <strong>Flow</strong> accelerationIntegral momentum balance for the control volume below leads to4P0A x-sec −P2A x-sec − ∫ τAwdAw = mv &avg−mv&avgw 3Increased momentum flowor flow acceleration