Chapt06

The great majority of our analyses are concerned with

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Unformatted text preview: s are concerned with laminar flow or with turbulent flow, and one should not normally design a flow operation in the transition region. Historical Outline | v v Since turbulent flow is more prevalent than laminar flow, experimenters have observed turbulence for centuries without being aware of the details. Before 1930 flow instruments were too insensitive to record rapid fluctuations, and workers simply reported | e-Text Main Menu | Textbook Table of Contents | Study Guide 6.1 Reynolds-Number Regimes 329 mean values of velocity, pressure, force, etc. But turbulence can change the mean values dramatically, e.g., the sharp drop in drag coefficient in Fig. 5.3. A German engineer named G. H. L. Hagen first reported in 1839 that there might be two regimes of viscous flow. He measured water flow in long brass pipes and deduced a pressure-drop law LQ p (const) 4 entrance effect (6.1) R This is exactly our laminar-flow scaling law from Example 5.4, but Hagen did not realize that the constant w...
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