Capillarity

A general term referring to phenomena attributable to the forces of surface or interfacial tension.

Capillary

A tube having a very small internal diameter.

Capillary Flow

Liquid flow in response to a difference in pressures across a curved interface.

Capillary Forces

Interfacial forces acting among oil, water, gas and solid in a capillary or in a porous medium. These determine the pressure difference (capillary pressure) across a fluid/fluid interface in the capillary or in a pore.

Capillary Rise

The process of liquid rise in a capillary such as when water rises in a partially immersed glass capillary.

Equation of Capillarity

See Young Laplace equation.

Interfacial Tension

See Surface Tension.

Surface Tension

The contracting force per unit length around the perimeter of a surface is usually referred to as surface tension if the surface separates gas from liquid or solid phases, and interfacial tension if the surface separates two nongaseous phases. Surface tension can also be expressed in units of energy per unit surface area. For practical purposes surface tension is frequently taken to reflect the change in surface free energy per unit increase in surface area.

Young Laplace Equation

The fundamental relationship giving the pressure difference across a curved interface in terms of the surface or interfacial tension and the principal radii of curvature. In the special case of a spherical interface, the pressure difference is equal to twice the surface (or interfacial) tension divided by the radius of curvature. Also referred to as the equation of capillarity.

For additional definitions and explanations, more complete dictionaries are available. See:

Dictionary of Colloid and Interface Science

The Language of Colloid and Interface Science

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