In engineering, the Moody chart or Moody diagram (also Stanton diagram) is a graph in
non-dimensional
Dimensionless quantities, or quantities of dimension one, are quantities implicitly defined in a manner that prevents their aggregation into units of measurement. ISBN 978-92-822-2272-0. Typically expressed as ratios that align with another sy ...
form that relates the
Darcy–Weisbach friction factor ''f''
''D'',
Reynolds number
In fluid dynamics, the Reynolds number () is a dimensionless quantity that helps predict fluid flow patterns in different situations by measuring the ratio between Inertia, inertial and viscous forces. At low Reynolds numbers, flows tend to ...
Re, and
surface roughness
Surface roughness or simply roughness is the quality of a surface of not being smooth and it is hence linked to human ( haptic) perception of the surface texture. From a mathematical perspective it is related to the spatial variability structure ...
for fully developed
flow in a circular pipe. It can be used to predict pressure drop or flow rate down such a pipe.
History
In 1944,
Lewis Ferry Moody plotted the
Darcy–Weisbach friction factor against
Reynolds number
In fluid dynamics, the Reynolds number () is a dimensionless quantity that helps predict fluid flow patterns in different situations by measuring the ratio between Inertia, inertial and viscous forces. At low Reynolds numbers, flows tend to ...
Re for various values of relative
roughness ε / ''D''.
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