p {\displaystyle p} is the pressure at the point at which pressure coefficient is being evaluated p ∞ {\displaystyle p_{\infty }} is the pressure in the freestream (i.e. remote from any disturbance) ρ ∞ {\displaystyle \rho _{\infty }} is the freestream fluid density (Air at sea level and 15 °C is 1.225 k g / m 3 {\displaystyle kg/m^{3}} ) V ∞ {\displaystyle V_{\infty }} is the freestream velocity of the fluid, or the velocity of the body through the fluid