Instabilities By Local Heating Below an Interface

Thermal lens oscillations, and associated hot-wire experiments, pertain to a class of instabilities produced when the free surface of a liquid is locally heated from below, generalizing to some extent the classical Benard-Marangoni instabilities [1-8]. They provided a host of original observations, including what is seemingly the first evidence of a type-ll intermittency in hydrodynamical experiments or the discovery of a new kind of propagating waves exhibiting a significant 1D-character. After two decades of study, this class of instabilities now receives a rather classical aspect [9] and deserves a review, which is presented in this paper. Beside the presentation of what is known and understood nowadays, the opportunity is taken to stress unsolved issues, therefore opening the way to future studies. This review completes and up-to-dates a previous one published one decade ago [10].