Description
Convection has traditionally been described by the mixing-length theory (MLT) in one-dimensional numerical models of stellar evolution. The MLT, due to its local nature, does not provide any information about mass exchange between a convective layer and a neighbouring stably-stratified layer. Theoretical arguments, laboratory experiments, as well as decades of astronomical observations suggest that convective boundary mixing (CBM) is a real phenomenon playing a vital role in our understanding of stellar physics and evolution. However, the physical processes involved in CBM depend on the type of convection zone in question and the mixing rate is difficult to quantify in most cases relevant to stars. I will provide an overview of our current understanding of CBM along with some historical developments leading to it. I will argue that the growth of convective layers can already be simulated with confidence in late stages of massive star evolution and that simplified hydrodynamic simulations combined with analytical theory are beginning to provide predictive models of CBM even for stars on the main sequence.
