# Drag Coefficient

Written by Jerry Ratzlaff. Posted in Dimensionless Numbers

Drag coefficient is a dimensionless number that expresses a force in the direction of flow due to pressure and surface stress on an object.

## FORMULA

$$C_D = \frac {2F_D} {\rho v^2 A}$$

Where:

$$C_D$$ = drag coefficient

$$F_D$$ = drag force

$$v$$ = velocity

$$\rho$$ = mass density

$$A$$ = area