In engineering, the Moody chart or Moody diagram (also Stanton diagram) is a graph in
non-dimensional
A dimensionless quantity (also known as a bare quantity, pure quantity, or scalar quantity as well as quantity of dimension one) is a quantity to which no physical dimension is assigned, with a corresponding SI unit of measurement of one (or 1) ...
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.
History
In 1944,
Lewis Ferry Moody plotted the
Darcy–Weisbach friction factor against
Reynolds number Re for various values of relative
roughness ε / ''D''.
[
]