Metastable and unstable hydrodynamics in multiphase lattice Boltzmann

Area of Science:

• Computational physics and chemistry
• Fluid dynamics
• Statistical mechanics

Background:

• Metastability in liquids is fundamental to phase transformations like nucleation and cavitation.
• Accurate simulation of metastable hydrodynamics is challenging due to slow convergence in conventional numerical methods.
• Intermolecular interactions and thermal fluctuations are critical but difficult to model accurately.

Purpose of the Study:

• To demonstrate the capability of the Shan-Chen lattice Boltzmann model for simulating metastable liquid hydrodynamics.
• To theoretically derive and numerically verify the structure factor of density fluctuations in metastable states.
• To investigate critical phenomena and phase separation dynamics within the metastable region.

Main Methods:

• Utilized the Shan-Chen lattice Boltzmann model for simulating fluid dynamics.
• Derived the theoretical structure factor of density fluctuations.
• Performed numerical simulations across various wave vectors, temperatures, and pressures, deep into the metastable region.

Main Results:

• Achieved high-precision agreement between theoretical predictions and numerical simulations for the structure factor.
• Observed consistent divergence of the static structure factor near the critical point and spinodal line.
• Confirmed theoretically predicted critical exponents and observed phase separation patterns similar to molecular dynamics.

Conclusions:

• The Shan-Chen lattice Boltzmann model accurately captures the hydrodynamics of metastable liquids.
• The model's success stems from its precise implementation of mechanical equilibrium conditions at the lattice level.
• This approach provides a powerful tool for studying complex phase transitions and critical phenomena.