. . "In continuum mechanics, Whitham's averaged Lagrangian method \u2013 or in short Whitham's method \u2013 is used to study the Lagrangian dynamics of slowly-varying wave trains in an inhomogeneous (moving) medium.The method is applicable to both linear and non-linear systems. As a direct consequence of the averaging used in the method, wave action is a conserved property of the wave motion. In contrast, the wave energy is not necessarily conserved, due to the exchange of energy with the mean motion."@en .