A physics-inspired alternative to spatial filtering for large-eddy simulations of turbulent flows

Spatial filtering is commonly used to justify LES equations and inform closure modeling. However, spatial filtering theory for LES is not without its shortcomings, including the precise definition of filtering near boundaries, the presence of commutation errors for non-uniform resolution, and difficulties associated with additional physical complexity such as two-phase interfaces. This presentation will introduce a new theory for LES using a coarsening procedure that imitates nature. This physics-inspired approach is equivalent to Gaussian filtering for single-phase wall-free flows with uniform resolution but opens up new insights even in that simple case. An alternative to the Germano identity will be introduced and used to define a dynamic procedure without the need for a test filter. Boundaries and nonuniform resolution can be treated seamlessly in this framework without commutation errors, and the divergence-free condition is retained for incompressible flows. Preliminary results for simple flows will be shown and potential extensions to more complex physics will be briefly discussed.