In fluid mechanics, capillary length is a characteristic length scale for an interface between two fluids which is subject both to gravitational acceleration and to a surface force due to surface tension in the interface.
The capillary length is defined as:
- For clean water and air at standard temperature and pressure, the capillary length is around 2.7 mm.
- For a soap bubble in air, the capillary length is around 4 meters (13 feet).
A capillary surface that has a characteristic length smaller than the capillary length can be considered a low Bond number surface. A sessile drop whose largest dimension is smaller than the capillary length, for example, will take the shape of spherical cap, which is the solution to the Young-Laplace equation with gravity completely absent.
- G.K. Batchelor, 'An Introduction To Fluid Dynamics', Cambridge University Press (1967)
|This fluid dynamics–related article is a stub. You can help Wikipedia by expanding it.|