Variational principle to derive the Stokes equations

A variational principle is proposed, which is aimed at deriving the Stokes equations. It is shown that the equations can be derived by requiring the stationarity of a quantity composed of the work by the pressure force and the entropy production, where the latter is expressed as the product of the stress and the strain in viscous flow. Discussion is given on the relation of this principle to the minimum dissipation principle for the Stokes flow.