Capillary number
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In fluid dynamics, the capillary number represents the relative effect of viscous forces versus surface tension acting across an interface between a liquid and a gas, or between two immiscible liquids. It is defined as
- <math>\text{Ca} \ \stackrel{\mathrm{def}}{=}\ \frac{\mu v}{\sigma} </math>
where <math>\mu</math> is the viscosity of the liquid, <math>v</math> is a characteristic velocity and <math>\sigma</math> is the surface or interfacial tension between the two fluid phases.
For low capillary numbers (a rule of thumb says less than <math>10^{-5}</math>), flow in porous media is dominated by capillary forces.
[edit] See also
Dimensionless numbers in fluid dynamics |
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| 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 |
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