Improved lattice Boltzmann model for immiscible multicomponent systems with high viscosity gradients at the interface

Area of Science:

• Computational fluid dynamics
• Multiphase flow modeling
• Numerical methods

Background:

• The lattice Boltzmann pseudopotential model is widely used for simulating fluid flow.
• Accurate modeling of immiscible fluids, especially with large viscosity ratios, remains a challenge.
• Existing models can suffer from spurious currents and limited stability.

Purpose of the Study:

• To propose improved discretization schemes for the lattice Boltzmann pseudopotential model.
• To enhance the modeling of incompressible multicomponent systems, particularly for large viscosity ratios.
• To achieve better control over interface dynamics and reduce numerical artifacts.

Main Methods:

• Developed alternative discretization schemes for the lattice Boltzmann pseudopotential model.
• Incorporated an explicit force term and second-order stream term discretization.
• Utilized a moments-based model for kinetic nonequilibrium distributions and high-order spatial derivative discretization.
• Investigated static bubble, Poiseuille flow, and fluid-fluid displacement scenarios.

Main Results:

• Achieved improved control of the interface region and interfacial tension.
• Demonstrated smaller spurious current magnitudes with increasing viscosity ratios.
• Showcased a significantly wider stability range compared to existing literature.
• Validated accuracy through simulations of static bubbles, Poiseuille flow, and fluid-fluid displacement.

Conclusions:

• The proposed discretization schemes offer a robust and simple extension of the pseudopotential model for multicomponent systems.
• The enhanced model provides superior accuracy and stability for simulating immiscible fluid flow with large viscosity ratios.
• This work contributes to more reliable computational fluid dynamics simulations in various engineering applications.