Theory of Diffusive Fluctuations

Diffusive Transport Enhanced by Thermal Velocity Fluctuations

We study the contribution of advection by thermal velocity fluctuations to the effective diffusion coefficient in a mixture of two identical fluids. We find good agreement between a simple fluctuating hydrodynamics theory and particle and finite-volume simulations. The enhancement of the diffusive transport depends on the system size L and grows as ln(L/L0) in quasi two-dimensional systems, whi...

Diffusive transport by thermal velocity fluctuations.

We study the contribution of advection by thermal velocity fluctuations to the effective diffusion coefficient in a mixture of two identical fluids. We find good agreement between a simple fluctuating hydrodynamics theory and particle and finite-volume simulations. The enhancement of the diffusive transport depends on the system size L and grows as ln(L/L₀) in quasi-two-dimensional systems, whi...

Dynamics of Fluctuations in Driven Diffusive Systems: Finite-size Effects

Enhancement of Diffusive Transport by Nonequilibrium Thermal Fluctuations

We study the contribution of advection by thermal velocity fluctuations to the effective diffusion coefficient in a mixture of two identical fluids. The steady-state diffusive flux in a finite system subject to a concentration gradient is enhanced because of long-range correlations between concentration fluctuations and fluctuations of the velocity parallel to the concentration gradient. The en...

Hydrodynamics and Fluctuations Outside of Local Equilibrium: Driven Diffusive Systems

We derive hydrodynamic equations for systems not in local thermodynamic equilibrium, that is, where the local stationary measures are "non-Gibbsian" and do not satisfy detailed balance with respect to the microscopic dynamics. As a main example we consider the driven diffusive systems (DDS), such as electrical conductors in an applied field with diffusion of charge carriers. In such systems, th...