Work

Non-Gaussian statistics of concentration fluctuations in free liquid diffusion

Year: 2026

Type: article

Abstract: We show that the three-point skewness of concentration fluctuations is nonvanishing in free liquid diffusion, even in the limit of vanishingly small mean concentration gradients. We exploit a high-Schmidt reduction of nonlinear Landau-Lifshitz hydrodynamics for a binary fluid, both analytically and by a massively parallel Lagrangian Monte Carlo simulation. Non-Gaussian statistics result from nonlinear coupling of concentration fluctuations to thermal velocity fluctuations, analogous to the turbulent advection of a passive scalar. Concentration fluctuations obey no central limit theorem, counter to the predictions of macroscopic fluctuation theory for generic diffusive systems.

Source: Physical Review Research

DOI: 10.1103/d27z-4fxz

Authors: Marco Bussoletti, Mirko Gallo, Amir Jafari, Gregory L. Eyink

Institutions: Sapienza University of Rome, Johns Hopkins University

Language: English

Topic: Fluid Dynamics and Turbulent Flows

Subfield: Computational Mechanics

Field: Engineering

Domain: Physical Sciences

Open Access status: gold

Estimated APC paid: $2,625

Funders: European Commission, European Research Council