Does the friction factor typically increases with the Reynolds number?
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The relationship between the friction factor and Reynolds number varies based on the flow conditions. At extreme Reynolds numbers, a power-law scaling suggests a decrease in the friction factor with increasing Reynolds number . In contrast, for high Reynolds numbers in fully developed turbulent pipe flow, the friction factor can decrease with an increase in Reynolds number, as observed in experiments ranging from 31×10^3 to 35×10^6 . Additionally, in micro-tubes with Reynolds numbers between 1500 and 8100, the friction factor and heat transfer factor decrease with increasing Reynolds number, showing a collapsing ratio for different cases, especially at Reynolds numbers above 3800 . Therefore, the behavior of the friction factor with respect to Reynolds number is dependent on the specific flow conditions and geometries being considered.
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155 Citations | The skin-friction coefficient typically follows a power law for Reynolds numbers below 62,000 and transitions to a log law at higher Reynolds numbers in turbulent channel flow. |
| Yes, the friction factor typically increases with the Reynolds number, as shown in the investigation of fully developed turbulent pipe flow in the high Reynolds number range. | |
| No, the friction factor decreases with increasing Reynolds number in the long micro-tube with dimples, as shown in the study. | |
12 Citations | At extreme Reynolds numbers, the friction factor follows a new power-law scaling, f = Ce/Re2/13, indicating a different behavior than the traditional increase with Reynolds number. |
63 Citations | Yes, the friction factor generally increases with the Reynolds number in pipe flow, as shown in the study up to ReD = 1.8 × 10^7, deviating from the Prandtl equation. |
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