# Capillary Number

Written by Jerry Ratzlaff on . Posted in Dimensionless Numbers

Capillary number, abbreviated as Ca, is a dimensionless number representing the relative effect of viscous forces against the surface tension between a liquid/ gas or liquid/ liquid interface.  It is the ratio of viscous forces to surface tension forces. The equations for Capillary Number and calculation are shown below.

 $$\large{ Ca = \frac { \mu \; v } { \sigma } }$$                  Where: $$\large{ Ca }$$ = Capillary number $$\large{ \mu }$$  (Greek symbol mu) = dynamic viscosity $$\large{ \sigma }$$  (Greek symbol sigma) = shear tension $$\large{ v }$$ = velocity of the fluid

Tags: Equations for Fluid