Aerodynamics, that branch of dynamics which treats of the force-relations of air or other elastic fluids. It is usually studied in conjunction with hydrodynamics (q.v.), of which it may be regarded as a special application. If the force-relations are such that equilibrium is the result, we have the division aerostatics. If motion is produced, aerokinetics. The practical applications of the science to aerial navigation introduce us to the art of aeronautics.