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.

 $$\large{ Ca = \frac { 2 \left(p \;-\;p_v \right) } {\rho U^2} }$$          $$\large{Ca = \frac { \left(p \;-\;p_v \right) } { \frac {1}{2} \rho U^2} }$$         Where: $$\large{ Ca }$$ = Cavitation number $$\large{ U }$$ = characteristic velocity $$\large{ \rho }$$  (Greek symbol rho) = density of the fluid $$\large{ p }$$ = local pressure $$\large{ p_v }$$ = vapor pressure Solve for: $$\large{ p = \frac {Ca \rho U^2} {2} \;+\; p_v }$$ $$\large{ p_v = p \;-\; \frac {Ca \rho U^2} {2} }$$ $$\large{ \rho = \frac { 2 \left (p \;-\;p_v \right)} {Ca U^2} }$$ $$\large{ v = \sqrt { \frac { 2 \left (p \;-\;p_v \right)} {Ca U^2} } }$$