Three-dimensional pseudopotential lattice Boltzmann model for multiphase flows at high density ratio.

Area of Science:

• Computational fluid dynamics
• Multiphase flow modeling
• Statistical physics

Background:

• Lattice Boltzmann methods (LBM) are powerful for fluid simulations.
• Existing pseudopotential LBM models face challenges with high density ratios and independent surface tension control.
• Accurate simulation of multiphase flows requires robust handling of interfaces and boundary conditions.

Purpose of the Study:

• To extend the 2D pseudopotential lattice Boltzmann model to a 3D version for high-density-ratio multiphase flow simulations.
• To achieve thermodynamic consistency and independent control of surface tension.
• To enhance model stability and accurately simulate various contact angles.

Main Methods:

• Incorporation of an additional source term into the evolution function.
• High-order Chapman-Enskog analysis to recover Navier-Stokes equations with an accurate pressure tensor.
• Development of an alternative geometric formulation for contact angle control.
• Implementation of an iterative initialization scheme for improved stability.
• Application of a wetting boundary scheme for precise contact angle realization.

Main Results:

• The 3D model accurately recovers Navier-Stokes equations with a correct pressure tensor.
• Thermodynamic consistency is achieved, allowing surface tension tuning independent of density ratio.
• A wide range of contact angles were precisely simulated using the wetting boundary scheme.
• The model demonstrated stability and capability in dynamic simulations of droplet impingement.

Conclusions:

• The proposed 3D pseudopotential lattice Boltzmann model is a stable and capable tool for multiphase flow simulations.
• The model successfully addresses limitations of previous methods, particularly for high density ratios.
• It offers independent control over surface tension and accurate realization of contact angles, crucial for various applications.