Solutions aux équations d'interfaces fluides

Laboratoire d'Aérothermique du CNRS, 4ter, route des Gardes, 92190 Meudon, France.

Abstract

Interface media are usually material phase separations. One can write both the balance equations system and the thermodynamic Gibbs relation, involving surface tensions, which leads to the expression of entropy production. From this last result we obtain, following the thermodynamics of irreversible processes, phenomenological relations between generalised fluxes and forces acting inside the interface as well as between interface and bulk.

The interface formalism may be partially extended to other situations as shock waves, flames and boundary layers, taking into account the fact that these phenomena disappear completely at equilibrium. There is no major difficulty to write correct balance equations. However, it is not at all easy to obtain constitutive relations and phenomenological equations in this case.

After recalling the general equations which govern fluid interface behaviours, we present solutions for a few problems of various nature : the Bénard-Marangoni instability, the Smith-Topley effect, the non stationary motion of a non adiabatic plane flame and the kinematic effects of fresh gases velocity perturbations on a premixed flame.