Hagen_number

Hagen number

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:

$\mathit{Hg} = -\frac{1}{\rho}\frac{\mathrm{d} p}{ \mathrm{d} x}\frac{L^3}{\nu^2}$

where:

$\frac{\mathrm{d} p}{\mathrm{d} x}$ is the pressure gradient
L is a characteristic length
$ρ$ is the fluid density
$ν$ is the kinematic viscosity

For natural convection

$\frac{\mathrm{d}p}{\mathrm{d}x} = \rho g \beta \Delta T,$

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

See also

v • d • 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 • Grashof • ‎Görtler • Hagen • Knudsen • Laplace • Lewis • Mach • Marangoni • Morton • Nusselt • Ohnesorge • Péclet • Prandtl (magnetic, turbulent) • Rayleigh • Reynolds (magnetic) • Richardson • Roshko • Rossby • Rouse • Ruark • Schmidt • Sherwood • Stanton • Stokes • Strouhal • Suratman • Taylor • Ursell • Weber • Weissenberg • Womersley