Fluctuating hydrodynamics of multispecies nonreactive mixtures

Area of Science:

• Fluid dynamics
• Computational physics
• Chemical engineering

Background:

• The Navier-Stokes equations describe fluid motion but require extensions for complex systems.
• Modeling thermal fluctuations in multispecies fluids is crucial for understanding phenomena like diffusion and instability.
• Existing numerical methods often struggle with the complexity of multicomponent fluid systems.

Purpose of the Study:

• To formulate fluctuating Navier-Stokes equations for multispecies, nonreactive fluids suitable for numerical solutions.
• To develop and validate an accurate and efficient numerical scheme for these stochastic partial differential equations.
• To apply the formulation to study nonequilibrium phenomena in multicomponent fluid mixtures.

Main Methods:

• Formulation of fluctuating Navier-Stokes equations for multispecies nonreactive fluids.
• Development of a numerical scheme based on prior work for single and binary mixtures.
• Testing the scheme at equilibrium and for various nonequilibrium scenarios, including diffusion barriers and instabilities.

Main Results:

• Successful numerical solution of stochastic partial differential equations for multispecies fluids.
• Accurate simulation of giant nonequilibrium concentration fluctuations in ternary mixtures.
• Demonstration of Rayleigh-Taylor instability triggering and reverse diffusion in ternary mixtures.

Conclusions:

• The developed formulation is robust and suitable for studying thermal fluctuations in multispecies fluids.
• The numerical scheme provides accurate results, validated against theory and experiments.
• This work offers a valuable tool for computational research in complex fluid systems.