The treatment of overshooting in stellar modelling: the need of a diffusive approach

Paolo Ventura

Abstract. The extent of the extra-mixing region which convective eddies travels beyond the formal border of convective zone is still under debate. A solution based on first principles is rendered difficult by the lack of any solution of the Navier-Stokes equations, which include the non locality required to solve this long standing problem. In this contribution we discuss the stellar astrophysical contexts where overshooting must be taken into acount, stressing those situations where the use of a diffusive approach, in which nuclear burning and mixing of chemicals are self-consistently coupled, is strongly recommended.