# Cavitation Number

Written by Jerry Ratzlaff on . Posted in Dimensionless Numbers

Cavitation number, abbreviated Ca, is a dimensionless number that expresses the relationship between the difference of a local absolute pressure from the vapor pressure and the kinetic energy per volume.

## Cavitation Number formulas

 $$\large{ Ca = \frac { 2\; \left(p \;-\;p_v \right) } {\rho\; U^2} }$$ $$\large{Ca = \frac { \left(p \;-\;p_v \right) } { \frac {1}{2} \; \rho\; U^2} }$$

### Where:

$$\large{ Ca }$$ = Cavitation number

$$\large{ U }$$ = characteristic velocity

$$\large{ \rho }$$  (Greek symbol rho) = density of fluid

$$\large{ p }$$ = local pressure

$$\large{ p_v }$$ = vapor pressure