# Cavitation Number

Written by Matt Milbury. Posted in Pump

$$Ca$$ - Cavitation Number 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.

## Formula

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

Where:

$$Ca$$ = Cavitation Number

$$p$$ = local [[Pressure|pressure]]

$$p_v$$ = fluid [[Vapor Pressure|vapor pressure]]

$$\rho$$ = fluid [[Density|density]]

$$v$$ = flow [[Characteristic Velocity|characteristic velocity]]

Solve for:

$$p = \frac {Ca \rho v^2} {2} \;+\; p_v$$

$$p_v = p \;-\; \frac {Ca \rho v^2} {2}$$

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

$$v = \sqrt { \frac { 2 \left (p \;-\;p_v \right)} {Ca v^2} }$$