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In engineering, the Moody chart or Moody diagram (also Stanton diagram) is a graph in non-dimensional form that relates the Darcy–Weisbach friction factor f D, Reynolds number Re, and surface roughness for fully developed flow in a circular pipe. It can be used to predict pressure drop or flow rate down such a pipe.
The Reynolds and Womersley Numbers are also used to calculate the thicknesses of the boundary layers that can form from the fluid flow’s viscous effects. The Reynolds number is used to calculate the convective inertial boundary layer thickness that can form, and the Womersley number is used to calculate the transient inertial boundary thickness that can form.
Dimensionless numbers (or characteristic numbers) have an important role in analyzing the behavior of fluids and their flow as well as in other transport phenomena. [1] They include the Reynolds and the Mach numbers, which describe as ratios the relative magnitude of fluid and physical system characteristics, such as density, viscosity, speed of sound, and flow speed.
Peel number: N P = coating (adhesion of microstructures with substrate) [15] Pixel: px: digital imaging (smallest addressable unit) Power factor: pf = electrical (real power to apparent power) Power number: N p
In fluid dynamics, the Reynolds number (Re) is a dimensionless quantity that helps predict fluid flow patterns in different situations by measuring the ratio between inertial and viscous forces. [2] At low Reynolds numbers, flows tend to be dominated by laminar (sheet-like) flow, while at high Reynolds numbers, flows tend to be turbulent.
The Reynolds number and power number fall from the above analysis if , n, and D are chosen to be the basis variables. If, instead, μ {\textstyle \mu } , n , and D are selected, the Reynolds number is recovered while the second dimensionless quantity becomes N R e p = P μ D 3 n 2 {\textstyle N_{\mathrm {Rep} }={\frac {P}{\mu D^{3}n^{2}}}} .
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From the chart, it is evident that the friction factor is never zero, even for smooth pipes because of some roughness at the microscopic level. The friction factor for laminar flow of Newtonian fluids in round tubes is often taken to be: [4] = [5] [2] where Re is the Reynolds number of the flow.