3D Simulations and MLT: I. Renzini's Critique

Understand

Renzini (1987) wrote an influential critique of mixing-length theory (MLT) as used in stellar evolution codes, and concluded that three-dimensional (3D) fluid dynamical simulations were needed to clarify several important issues.

• We have critically explored the limitations of the numerical methods and conclude that they are approaching the required accuracy.
• Implicit large eddy simulations (ILES) automatically connect large scale turbulence to a Kolmogorov cascade below the grid scale, allowing turbulent boundary layers to remove singularities that appear in the theory.
• Interactions between coherent structures give multi-modal behavior, driving intermittency and fluctuations.