Capillary pressure in a tube (contact angle)


In a sufficiently narrow tube of circular cross-section of radius “a”, the interface between two fluids forms a meniscus that is a portion of the surface of a sphere with radius R. The pressure jump across this surface is related to the surface tension, the tube’s cross section radius and the contact angle of the meniscus.

Related formulas


ΔpPressure difference (Pa)
γSurface tension (N/m)
θContact angle (degrees)
aTube's cross section radius (m)