Reynolds Number and Friction Factor: How Does It Work?

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An increase in Reynolds number indicates a transition from laminar to turbulent flow, which typically leads to greater energy loss due to eddies. However, the friction factor decreases with higher Reynolds numbers, as shown in the Moody diagram and supported by experimental data. This counterintuitive relationship occurs because the increase in flow velocity affects dynamic pressure more significantly than the decrease in friction factor. Consequently, while turbulence increases flow complexity, the overall wall shear stress can still rise due to the dominant effect of dynamic pressure. Understanding this relationship is crucial for accurate fluid dynamics analysis.
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So, I understand that when reynolds number increases, the fluid becomes more turbulent, and there is a greater energy loss due to formation of eddies. However, shouldn't this increase in reynolds number cause an increase in friction as well?

But, according to the moody diagram (http://piping-designer.com/wiki/images/0/05/Moody-Diagram.jpg)
as well as experimental data I have collected, it seems that friction factor actually decreases as reynolds number increases. How is this possible, if increasing turbulence causes more haphazard flow, wouldn't their be greater frictional forces?
 
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The drag shear stress at the wall is equal to the friction factor times the dynamic pressure ##\rho \frac{v^2}{2}##, and the latter increases with flow velocity more than the friction factor decreases. So the net effect is an increase in the frictional wall stress.
 

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