  We study the effects of polymer additives on turbulence generated by the
ubiquitous Rayleigh-Taylor instability. Numerical simulations of complete
viscoelastic models provide clear evidence that the heat transport is enhanced
up to 50% with respect to the Newtonian case. This phenomenon is accompanied by
a speed up of the mixing layer growth. We give a phenomenological
interpretation of these results based on small-scale turbulent reduction
induced by polymers.
