Nonlinear energy dissipation and transfers in coarsening systems.

Verma, Mahendra K; Agrawal, Ramgopal; Yadav, Pradeep Kumar; Puri, Sanjay · Phys Rev E · 2023

basic_science · Level V

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Abstract

During coarsening, small structures disappear, leaving behind only large ones. Here we study the spectral energy transfers in Model A, where the order parameter ϕ evolves via nonconserved dynamics. We show that the nonlinear interactions dissipate fluctuations and facilitate energy transfers among the Fourier modes so that only ϕ(k=0), where k is the wave number, survives at the end and approaches the asymptotic value +1 or -1. We contrast the coarsening evolution for the initial conditions with 〈ϕ(x,t=0)〉=0 and with uniformly positive or negative ϕ(x,t=0).