Geometrical structures of the instantaneous current and their macroscopic effects: vortices and perspectives in non-gradient models

First we discuss the definition of the instantaneous current in interacting particle systems, in particular in mass-energy systems and we point out its role in the derivation of the hydrodynamics. Later we present some geometrical structures of the instantaneous current when the rates satisfy a common symmetry. These structures give some new ideas in non-gradient models and show new phenomenology in diffusive interacting particle systems. Specifically, we introduce models with vorticity and present some new perspectives on the link between the Green-Kubos formula and the hydrodynamics of non-gradient models.