  The impressive development of global numerical simulations of turbulent
stellar interiors unveiled a variety of possible differential rotation (solar
or anti-solar), meridional circulation (single or multi-cellular), and dynamo
states (stable large scale toroidal field or periodically reversing magnetic
fields). Various numerical schemes, based on the so-called anelastic set of
equations, were used to obtain these results. It appears today mandatory to
assess their robustness with respect to the details of the numerics, and in
particular to the treatment of turbulent sub-grid scales. We report on an
ongoing comparison between two global models, the ASH and EULAG codes. In EULAG
the sub-grid scales are treated implicitly by the numerical scheme, while in
ASH their effect is generally modelled by using enhanced dissipation
coefficients. We characterize the sub-grid scales effect in a turbulent
convection simulation with EULAG. We assess their effect at each resolved scale
with a detailed energy budget. We derive equivalent eddy-diffusion coefficients
and use the derived diffusivities in twin ASH numerical simulations. We find a
good agreement between the large-scale flows developing in the two codes in the
hydrodynamic regime, which encourages further investigation in the
magnetohydrodynamic regime for various dynamo solutions.
