In
fluid dynamics, the
drag coefficient (commonly denoted as:
cd,
cx or
cw) is a
dimensionless quantity that is used to quantify the
drag or resistance of an object in a fluid environment, such as air or water. It is used in the
drag equation, where a lower drag coefficient indicates the object will have less
aerodynamic or
hydrodynamic drag. The drag coefficient is always associated with a particular surface area.