P {\displaystyle P\;} is static pressure, 1 2 ρ v 2 {\displaystyle {\tfrac {1}{2}}\rho v^{2}} is dynamic pressure, usually denoted by q {\displaystyle q\;} , ρ {\displaystyle \rho \,} is the density of the fluid, v {\displaystyle v\,} is the flow velocity, and P 0 {\displaystyle P_{0}\;} is total pressure which is constant along any streamline.