New paper shows that surface thermodynamics can be used on shock waves

Our paper entitled Nonequilibrium thermodynamics of surfaces captures the energy conversions in a shock wave has been published in the open access journal Chemical Physics Letters X.

In the letter, we develop a theory for the entropy production in a shock wave using Gibbs’ excess properties in the framework of non-equilibrium thermodynamics (NET) of surfaces. The theory was used to analyze numerical results from non-equilibrium molecular dynamics simulations. The Gibbs equation for surface excess thermodynamic variables was confirmed by comparison with a direct numerical evaluation of the entropy balance. The NET analysis showed that the dominant contribution to the entropy production is the dissipation of kinetic and compression energy. The new framework to describe shock waves opens the door to accurate representations of energy conversions in shock waves.

The work described in the letter is a result of work that has been going on for several years. However, there are still many interesting physical phenomena in shock waves that we would like to better understand. The great advantage with surface thermodynamics, is that it relies on bulk properties extrapolated to the shock front. The continuous thermodynamic description across the shock wave however, remains elusive, as exemplified by the anisotropy in the different contributions to the kinetic temperature at the shock front. The picture below shows the positive peak in the entropy production at the shock front.