Regular Article

Asymmetric energy transfers in driven nonequilibrium systems and arrow of time

Department of Physics, Indian Institute of Technology, Kanpur 208016, India

^a e-mail: mkv@iitk.ac.in

Received: 31 March 2019
Received in final form: 3 June 2019
Published online: 2 September 2019

Abstract

Fundamental interactions are either fully or nearly symmetric under time reversal. But macroscopic phenomena may have a definite arrow of time. From the perspectives of statistical physics, the direction of time is towards increasing entropy. In this paper, we provide another perspective on the arrow of time. In driven-dissipative nonequilibrium systems forced at large scale, the energy typically flows from large scales to dissipative scales. This generic and multiscale process breaks time reversal symmetry and principle of detailed balance, thus can yield an arrow of time. In this paper we propose that conversion of large-scale coherence to small-scales decoherence could be treated as a dissipation mechanism for generic physical systems. We illustrate the above processes using turbulence as an example. In the paper we also describe exceptions to the above scenario, mainly systems exhibiting no energy cascade or inverse energy cascade.