Gianni Jona Lasinio

Dipartimento di Fisica, Università "Sapienza" di Roma

On thermodynamic transformations

In a transformation between stationary states (equilibrium or nonequilibrium) a system necessarily goes through deviations from stationarity which are small if the transformation is quasi-static. Classical thermodynamics is unable to describe this intrinsically dynamic aspect. In thermodynamic books quasi-static transformations are introduced in a descriptive way appealing to intuition without any mathematics. We show that it is possible to analyse mathematically these transformations by expanding thermodynamic variables in powers of 1/T for large T, where T is the duration of the transformation. In this way we obtain equations relating changes of thermodynamic functionals to solutions of hydrodynamics slightly deviating from a stationary state. Optimization problems arise in this context.

[SLIDES PDF]