This is a work in progress with Laure St-Raymond (ENS Lyon) andFrédéric Faure (IF). Stratification of the density in anincompressible fluid is responsible for the propagation of internalwaves. In domains with topography, these waves exhibit interestingproperties. In particular, numerical and lab experiments performed inthe team of Thierry Dauxois, especially by Christophe Brouzet, at ENSLyon, show that in 2D these waves concentrate on attractors for somegeneric frequencies of the forcing. I will present simplifiedmathematical model and discuss some of their properties.