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Grashof number
From Wikipedia, the free encyclopedia
The Grashof number is a dimensionless number in fluid dynamics which approximates the ratio of the buoyancy force to the viscous force acting on a fluid. It is named after the German engineer Franz Grashof.
where
- g = acceleration due to Earth's gravity
- β = volumetric thermal expansion coefficient
- Ts = source temperature
- T∞ = quiescent temperature
- L = characteristic length
- ν = kinematic viscosity
The product of the Grashof number and the Prandtl number gives the Rayleigh number, a dimensionless number that characterizes convection problems in heat transfer.
There is an analogous form of the Grashof number used in cases of natural convection mass transfer problems.
where
and
- g = acceleration due to Earth's gravity
- Ca,s = concentration of species a at surface
- Ca,a = concentration of species a in ambient medium
- L = characteristic length
- ν = kinematic viscosity
- ρ = fluid density
- Ca = concentration of species a
- T = constant temperature
- p = constant pressure
- Jaluria, Yogesh. Natural Convection Heat and Mass Transfer (New York: Pergamon Press, 1980).
| Dimensionless numbers in fluid dynamics |
|---|
| Archimedes • Bagnold • Bond • Brinkman • Capillary • Damköhler • Deborah • Eckert • Ekman • Euler • Froude • Galilei • Grashof • Hagen • Knudsen • Laplace • Lewis • Mach • Marangoni • Nusselt • Ohnesorge • Péclet • Prandtl • Rayleigh • Reynolds • Richardson • Rossby • Schmidt • Sherwood • Stanton • Stokes • Strouhal • Weber • Weissenberg • Womersley |