A covariant approach to relativistic large-eddy simulations: The fibration picture

Understand

Models of turbulent flows require the resolution of a vast range of scales, from large eddies to small-scale features directly associated with dissipation.

• As the required resolution is not within reach of large scale numerical simulations, standard strategies involve a smoothing of the fluid dynamics, either through time averaging or spatial filtering.
• These strategies raise formal issues in general relativity, where the split between space and time is observer dependent.
• To make progress, we develop a new covariant framework for filtering/averaging based on the fibration of spacetime associated with fluid elements and the use of Fermi coordinates to facilitate a meaningful local analysis.