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Updated: Jul 31, 2026
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An Analog Macroscopic Technique for Studying Molecular Hydrodynamic Processes in Dense Gases and Liquids
Published on: December 4, 2017
Theory of the lattice Boltzmann method: two-fluid model for binary mixtures
Li-Shi Luo1, Sharath S Girimaji
1ICASE, Mail Stop 132C, NASA Langley Research Center, 3 West Reid Street, Building 1152, Hampton, Virginia 23681-2199, USA.
Summary
A new two-fluid lattice Boltzmann model for binary mixtures allows independent control of viscosity and diffusion. This model simulates both miscible and immiscible fluids, overcoming limitations of existing methods.
Area of Science:
- Computational fluid dynamics
- Kinetic theory
- Multiphase flow modeling
Background:
- Existing single-fluid lattice Boltzmann models often restrict fluid property ratios.
- Simulating binary mixtures with independent viscosity and diffusion is challenging.
- Current models struggle to simulate both miscible and immiscible fluid behaviors.
Purpose of the Study:
- Develop a two-fluid lattice Boltzmann model for binary mixtures.
- Enable independent control over viscosity and diffusion coefficients.
- Allow simulation of both miscible and immiscible fluid systems.
Main Methods:
- Formal derivation from kinetic theory.
- Discretization of two-fluid Boltzmann equations.
- Independent treatment of mutual and self-collisions.
- Utilizing distinct relaxation-time scales for collision terms.
Main Results:
- Achieved independent variation of viscosity and diffusion coefficients.
- Successfully simulated both miscible and immiscible binary fluid mixtures.
- Demonstrated flexibility by altering the sign of the mutual-collision term.
- Overcame limitations of single-fluid models regarding Prandtl and Schmidt numbers.
Conclusions:
- The developed two-fluid lattice Boltzmann model offers enhanced flexibility for binary mixtures.
- The model provides independent control over transport coefficients.
- It is capable of simulating diverse fluid behaviors, including miscibility and immiscibility.
- Extension to multiscalar mixing is straightforward.
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