Transfert de masse à l'interface d'un film turbulent libre ou cisaillé

Abstract

Mass transfer of weakly soluble gases through gas-liquid turbulent interfaces is analysed by means of the Large-Eddy Simulation technique. Two different flow configurations are considered, namely an open channel flow with a shear-free surface and a liquid layer driven by an interfacial shear. The very good agreement found between the global mass transfer coefficients provided by the simulation and those coming for measurements validates the LES approach which is used for the first time in high-Schmidt-number mass transfer problems. The relationship between the turbulent motions active close to the interface and the instantaneous concentration field is investigated both statistically and dynamically. The validity of available mass transfer models based on the concept of surface renewal is then discussed in the light of this information which is still, to a large degree, unachievable in experiments.