Coagulation drives turbulence in binary fluid mixtures

Akshay Bhatnagar; Prasad Perlekar; Dhrubaditya Mitra

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arXiv · 2109.09671

Coagulation drives turbulence in binary fluid mixtures

Akshay Bhatnagar·Prasad Perlekar·Dhrubaditya Mitra

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Abstract

We use direct numerical simulations and scaling arguments to study coarsening in binary fluid mixtures with a conserved order parameter in the droplet-spinodal regime -- the volume fraction of the droplets is neither too small nor symmetric -- for small diffusivity and viscosity. Coagulation of droplets drives a turbulent flow that eventually decays. We uncover a novel coarsening mechanism, driven by turbulence where the characteristic length scale of the flow is different from the characteristic length scale of droplets, giving rise to a domain growth law of $t^{1/2}$, where $t$ is time. At intermediate times, both the flow and the droplets form self-similar structures: the structure factor $S(q) \sim q^{-2}$ and the kinetic energy spectra $E(q) \sim q^{-5/3}$ for an intermediate range of $q$, the wavenumber.

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Akshay Bhatnagar, Prasad Perlekar, Dhrubaditya Mitra. 2021-09-20. Coagulation drives turbulence in binary fluid mixtures. https://arxiv.org/abs/2109.09671

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