  We assess the viability of a recently proposed novel approach to LES for
compressible variable density flows by means of a priori tests. The a priori
tests have been carried out filtering a two-dimensional DNS database of the
classic lock-exchange benchmark. The tests confirm that additional terms should
be accounted for in subgrid scale modeling of variable density flows, with
respect to the terms usually considered in the traditional approach. Several
alternatives for the modeling of these terms are assessed and discussed.
