Interfacial Instability in Fluid Layers Under Thermal Constraints

Abstract

Although reports on interfacial convection were published before the beginning of our century and their relevance had been discussed by several authors, a systematic study of the phenomenology did not really occur until the experimental work conducted by Henri BENARD /l/. This author posed himself the task of providing a quantitative description of the (steady) flows arising in a horizontal thin liquid layer heated from below and open to the ambient air. There is some evidence that Benard perceived the relevant role of surface tension in his problem but, however, he did not really address himself the question of interest to us here: how and how much the liquid-air interface affected or was affected by the observed convective flows. It took some fifty years until the right experimental (BLOCK /2/, KOSCHMIEDER /3/) and theoretical questions (PEARSON /4/) were asked and, to a first approximation, unambiguously answered (BIRIKH /5/, NIELD /6/, STERNLING and SCRIVEN /7/).Yet, today we do not dispose of a complete theory of the interfacial phenomena involved in Benard convection. However,interfacial convection is so relevant to chemical engineering, materials sciences, crystal growth (LANGER /8/, OSTRACH /9/, SCHWABE and SCHARMANN/10/) that many aspects of the problems have already been elucidated.