  In a previous work we devised a framework to derive generalised gradient
systems for an evolution equation from the large deviations of an underlying
microscopic system, in the spirit of the Onsager-Machlup relations. Of
particular interest is the case where the microscopic system consists of random
particles, and the macroscopic quantity is the empirical measure or
concentration. In this work we take the particle flux as the macroscopic
quantity, which is related to the concentration via a continuity equation. By a
similar argument the large deviations can induce a generalised gradient or
Generic system in the space of fluxes. In a general setting we study how flux
gradient or generic systems are related to gradient systems of concentrations.
The arguments are explained by the example of reacting particle systems, which
is later expanded to include spatial diffusion as well.
