Lattice Boltzmann accelerated direct simulation Monte Carlo for dilute gas flow simulations

Area of Science:

• Computational Fluid Dynamics
• Multiscale Modeling
• Non-equilibrium Gas Flows

Background:

• Simulating gas flows with varying non-equilibrium requires adaptive resolution techniques.
• Traditional methods like Direct Simulation Monte Carlo (DSMC) are computationally intensive for large-scale flows.
• The lattice Boltzmann (LB) method excels in simulating bulk fluid behavior under Navier-Stokes hydrodynamics.

Purpose of the Study:

• To develop and present a novel hybrid computational framework coupling DSMC and LB methods.
• To investigate the performance of this hybrid scheme for isothermal gas flows.
• To assess the computational efficiency and accuracy compared to full DSMC simulations.

Main Methods:

• A concurrent multiscale method is proposed, integrating DSMC for non-equilibrium regions (e.g., near boundaries) and LB for bulk flow.
• The scheme is applied to the dilute gas Couette flow problem.
• Isothermal flow conditions are assumed for the coupling.

Main Results:

• The hybrid DSMC-LB method demonstrates significant computational gains over full DSMC simulations.
• The LB method in the bulk flow accelerates the DSMC treatment of the Knudsen layer.
• LB effectively acts as a computational accelerator for DSMC.

Conclusions:

• The hybrid particle-continuum framework offers a more efficient approach to simulating rarefied gas dynamics.
• Coupling DSMC with LB provides substantial speedups, making complex flow simulations more feasible.
• This multiscale approach enhances the computational treatment of non-equilibrium phenomena in fluid dynamics.