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The Hagen number is a dimensionless number used in forced flow calculations. It is the forced flow equivalent of the Grashof number and was named after the German hydraulic engineer G. H. L. Hagen.

It is defined as:

where:

•  is the pressure gradient


• L is a characteristic length


•  is the fluid density


•  is the kinematic viscosity

For natural convection

and so the Hagen number then coincides with the Grashof number.

[edit]See also

[hide] v t e Dimensionless numbers in fluid dynamics Archimedes Atwood Bagnold Bejan Biot Bond Brinkman Capillary Cauchy Damköhler Dean Deborah Eckert Ekman Eötvös Euler Froude Galilei Graetz Gra