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Stellar evolution models of massive stars are important for many areas ofastrophysics, for example nucleosynthesis yields, supernova progenitor modelsand understanding physics under extreme conditions. Turbulence occurs in starsprimarily due to nuclear burning at different mass coordinates within the star.The understanding and correct treatment of turbulence and turbulent mixing atconvective boundaries in stellar models has been studied for decades but stilllacks a definitive solution. This paper presents initial results of a study onconvective boundary mixing (CBM) in massive stars. The 'stiffness' of aconvective boundary can be quantified using the bulk Richardson number($\textrm{Ri}_B$), the ratio of the potential energy for restoration of theboundary to the kinetic energy of turbulent eddies. A 'stiff' boundary($\textrm{Ri}_B \sim 10^4$) will suppress CBM, whereas in the opposite case a'soft' boundary ($\textrm{Ri}_B \sim 10$) will be more susceptible to CBM. Oneof the key results obtained so far is that lower convective boundaries (closerto the centre) of nuclear burning shells are 'stiffer' than the correspondingupper boundaries, implying limited CBM at lower shell boundaries. This is inagreement with 3D hydrodynamic simulations carried out by Meakin and Arnett[The Astrophysical Journal 667:448-475, 2007]. This result also hasimplications for new CBM prescriptions in massive stars as well as for nuclearburning flame front propagation in Super-Asymptotic Giant Branch stars and alsothe onset of novae.

Linking 1D Evolutionary to 3D Hydrodynamical Simulations of Massive Stars