Drag coefficient

In fluid dynamics, the drag coefficient (commonly denoted as: C d {\displaystyle \scriptstyle C_{\mathrm {d} }\,}, C x {\displaystyle \scriptstyle C_{\mathrm {x} }\,} or C w {\displaystyle \scriptstyle C_{\mathrm {w} }\,}) 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 in which 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.