An example of entropy balance in natural convection,Part 1: the usual Boussinesq equations

Numerical simulations of natural convection in cavities performed with the usual Boussinesq equations result in an unbalanced irreversibility budget. Thermodynamic analysis shows that these equations represent a system that exchanges with the surroundings, not only two heat fluxes, but also two fluxes of mechanical energy: an input, that generates the fluid motion, and an output, due to viscous friction. After this analysis, the thermodynamic discrepancies can be explained. To cite this article: M. Pons, P. Le Quéré, C. R. Mecanique 333 (2005).