Phys Rev E. 2016 Feb;93(2):022210. doi: 10.1103/PhysRevE.93.022210. Epub 2016 Feb 16.
Physical review. E
Hans Dierckx, Henri Verschelde
PMID: 26986334 DOI: 10.1103/PhysRevE.93.022210
The dynamics of many natural systems is dominated by nonlinear waves propagating through the medium. We show that in any extended system that supports nonlinear wave fronts with positive surface tension, the asymptotic wave-front dynamics can be formulated as a gradient system, even when the underlying evolution equations for the field variables cannot be written as a gradient system. The variational potential is simply given by a linear combination of the occupied volume and surface area of the wave front and changes monotonically over time.