Symmetric form of governing equations for capillary fluids
  In classical continuum mechanics, quasi-linear systems of conservation laws can be symmetrized if they admit an additional convex conservation law. In particular, this implies the hyperbolicity of governing equations. For capillary fluids, the internal energy depends not only on the density but also on its derivatives with respect to space variables. Consequently, the governing equations belong to the class of dispersive systems. In that case we propose a symmetric form of governing equations which is different from the classical Godunov -Friedrichs - Lax representation. This new symmetric form implies the stability of constant solutions. 
Sergey Gavrilyuk, Henri Gouin (MSNMGP, LMMT)