Capillary Rise

vCalc Reviewed
Equation / Last modified by KurtHeckman on 2017/01/19 19:13
Capillary Rise
Variable Instructions Datatype
`(sigma)"Surface Tension of the Fluid"` Enter the mass component of surface tension coefficient. Surface tension is typically in units of `g/s^2` or `kg/s^2`. The s^2 is added. Enter the mass and the s^2 is added. Decimal (g)
`(lambda)"Meniscus Angle"` Enter the angle between the minisucs and the capillary tube as degrees Decimal (°)
`(rho_w)"Density of the Fluid"` Enter the density of the fluid Decimal (kg/m³)
`(R)"Radius of the Capillary Tube"` Enter the radius of the capillary tube Decimal (mm)
Engineering->Civil Engineering
4 variables
vCalc.Capillary Rise

The Capillary Rise calculator equation computes the height of liquid in a small diameter tube due to capillary force on the liquid.  CapillaryRise-illustration.png

INSTRUCTIONS: Choose your preferred units and enter the following:

  • (σ) This is the surface tension of the fluid
  • (λ) This is the meniscus angle
  • (ρw) This is the density of the fluid
  • (R) This is the radius of the capillary tube

Capillary Rise: The calculator returns the rise in meters.  However this can be automatically converted into other length units via the pull-down menu.

General Information

The force on the fluid is caused by the attraction between the solid and the liquid which pulls the water up into the tube.  The water rises until the force of capillary attraction is offset by the force due to gravity on the water column.  The surface of the water in the tube meets the walls of the tube at a contact angle that is unique to the fluid, in this case water, creating a concave upper surface to the water.  The rise of the water is computed from the following:
 surface tension of the water

  • angle of the meniscus, the angle at which the water surface intersects the sides of the tube
  • density of the fluid
  • local acceleration due to gravity (assumed at sea level)
  • the radius of the tube