# Drag Coefficient

Written by Jerry Ratzlaff on . Posted in Dimensionless Numbers

## Drag Coefficient

Drag coefficient ( $$C_d$$ ) (dimensionless number) expresses a force in the direction of flow due to pressure and surface stress on an object.

### Drag Coefficient FORMULA

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

Where:

$$\large{ C_d }$$ = drag coefficient

$$\large{ F_d }$$ = drag force

$$\large{ v }$$ = velocity

$$\large{ \rho }$$  (Greek symbol rho) = mass density

$$\large{ A }$$ = area