# Cavitation Number

on . Posted in Dimensionless Numbers

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

## Cavitation number formula

$$\large{ Ca = \frac{ 2\; \left(p \;-\;p_v \right) }{\rho\; U^2} }$$
Symbol English Metric
$$\large{ Ca }$$ = Cavitation number $$\large{ dimensionless }$$
$$\large{ U }$$ = characteristic velocity of flow $$\large{\frac{ft}{sec}}$$ $$\large{\frac{m}{s}}$$
$$\large{ \rho }$$  (Greek symbol rho) = density of fluid $$\large{\frac{lb}{ft^3}}$$ $$\large{\frac{kg}{m^3}}$$
$$\large{ p }$$ = local pressure $$\large{\frac{lbf}{in^2}}$$ $$\large{Pa}$$
$$\large{ p_v }$$ = vapor pressure $$\large{\frac{lbf}{in^2}}$$ $$\large{Pa}$$