Multiple-relaxation-time discrete Boltzmann modeling of multicomponent mixture with nonequilibrium effects

Area of Science:

• Computational fluid dynamics
• Statistical mechanics
• Multiphase flow modeling

Background:

• Existing models often simplify complex fluid behaviors.
• Understanding nonequilibrium effects in multicomponent mixtures is crucial for advanced simulations.
• The Navier-Stokes equations have limitations in describing kinetic phenomena.

Purpose of the Study:

• To develop and validate a multiple-relaxation-time discrete Boltzmann model (DBM) for multicomponent mixtures.
• To investigate compressible, hydrodynamic, and thermodynamic nonequilibrium effects.
• To analyze the entropy production mechanism and nonequilibrium behaviors in fluid flows, specifically the Kelvin-Helmholtz instability (KHI).

Main Methods:

• Implementation of a multiple-relaxation-time discrete Boltzmann model (DBM).
• Incorporation of adjustable specific heat ratio and Prandtl number for versatility.
• Simulation of compressible Kelvin-Helmholtz instability (KHI) to study nonequilibrium phenomena.

Main Results:

• The DBM accurately captures multicomponent Navier-Stokes equations and diffusion laws in the hydrodynamic limit.
• Analysis of KHI revealed similarities in mixing degree and fluid flow across varying thermal conductivity and initial temperatures.
• Maximum and minimum temperatures showed distinct trends based on initial temperature gradients, indicating their influence.

Conclusions:

• The DBM provides enhanced kinetic information beyond traditional fluid dynamics models.
• Non-equilibrium effects in multicomponent mixtures, particularly during KHI, can be effectively studied using this DBM.
• While heat conduction and temperature have minor impacts on KHI morphology, temperature gradients significantly affect thermal behavior.