Isomorphic multifractal shear flows for hard disks via adiabatic and isokinetic nonequilibrium molecular dynamics

Identical particle trajectories can result from driven shear flows of two different types: (i) thermostatted flows, simulating a nonequilibrium steady state, and (ii) adiabatic flows, in which the irreversible heating associated with viscous work is not extracted from the system. This trajectory isomorphism applies to shears of hard particles, such as hard disks and spheres. Here we simulate such isomorphic shear flows. We also discuss the associated instantaneous Lyapunov spectra, which are not isomorphic. We extrapolate the dissipative hard-disk spectra to the large-system limit.