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Diffusion in stationary flow from mesoscopic nonequilibrium thermodynamics.
I Santamaría-Holek1, D Reguera, J M Rubí
1Departament de Física Fonamental-CER Física de Sistemes Complexos, Facultat de Física, Universitat de Barcelona, Diagonal 647, 08028 Barcelona, Spain.
Summary
We analyzed Brownian particle diffusion in fluid flow, revealing a violation of the fluctuation-dissipation theorem. Our nonequilibrium thermodynamics approach provides a complete description for inertial and diffusion regimes.
Area of Science:
- Statistical Physics
- Soft-Condensed Matter Physics
- Fluid Dynamics
Background:
- Brownian motion describes particle diffusion in fluids.
- Stationary flow introduces nonequilibrium conditions.
- Understanding particle diffusion under flow is crucial for soft-condensed matter systems.
Purpose of the Study:
- To derive and analyze the Fokker-Planck equation for Brownian particle diffusion in stationary flow.
- To investigate the violation of the fluctuation-dissipation theorem in this system.
- To develop a complete description of the system in inertial and diffusion regimes.
Main Methods:
- Utilizing nonequilibrium thermodynamics in phase space.
- Deriving the Fokker-Planck equation.
- Implementing hydrodynamic regimes via first moments of nonequilibrium distribution.
Main Results:
- Obtained a Fokker-Planck equation consistent with other methods but showing fluctuation-dissipation theorem violation.
- Derived relaxation equations for diffusion current and pressure tensor.
- Achieved a comprehensive description of inertial and diffusion regimes.
Conclusions:
- The proposed method is simple and general.
- It is applicable to complex soft-condensed matter systems with coupled degrees of freedom.
- This work advances the understanding of nonequilibrium statistical mechanics.