Hagen number

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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.

It is defined as:

<math>

\mathit{Hg} = -\frac{1}{\rho}\frac{\mathrm{d} p}{ \mathrm{d} x}\frac{L^3}{\nu^2} </math>

where:

• <math>\frac{\mathrm{d} p}{\mathrm{d} x}</math> is the pressure gradient
• L is a characteristic length
• <math>\rho</math> is the fluid density
• <math>\nu</math> is the kinematic viscosity

For natural convection

<math>

\frac{\mathrm{d}p}{\mathrm{d}x} = \rho g \beta \Delta T, </math>

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

[edit] See also

v • d • e Dimensionless numbers in fluid dynamics

Archimedes • Bagnold • Biot • Bond • Brinkman • Capillary • Damköhler • Dean • Deborah • Eckert • Ekman • Eötvös • Euler • Froude • Galilei • Grashof • Hagen • Knudsen • Laplace • Lewis • Mach • Magnetic Reynolds • Marangoni • Morton • Nusselt • Ohnesorge • Péclet • Prandtl • Rayleigh • Reynolds • Richardson • Roshko • Rossby• Ruark • Schmidt • Sherwood • Stanton • Stokes • Strouhal • Suratman • Taylor • Weber • Weissenberg • Womersley

de:Hagen-Zahl

fr:Nombre de Hagen it:Numero di Hagen