Fluid-solid boundary conditions for multiparticle collision dynamics.

Area of Science:

• Computational physics
• Soft matter physics
• Fluid dynamics

Background:

• Accurate simulation of colloidal particles requires precise modeling of colloid-solvent interactions.
• Existing multiparticle collision dynamics (MPCD) methods face challenges in representing boundary conditions faithfully.

Purpose of the Study:

• To evaluate different stick boundary condition proposals in MPCD simulations.
• To investigate their performance in both stationary and moving boundary scenarios.
• To compare collision rules for mitigating spurious slip and their impact on colloid thermal motion.

Main Methods:

• Utilizing the multiparticle collision dynamics (MPCD) method.
• Simulating plane Poiseuille flow with stationary boundaries.
• Performing particle-based colloid simulations with mobile, thermally affected boundaries.
• Comparing various collision rules and stochastic reflection methods.

Main Results:

• Stochastic reflection at solid boundaries inaccurately represents stick conditions.
• Bounce-back conditions are effective for both stationary and mobile surfaces.
• Specific collision rules successfully minimize spurious slip near surfaces.
• The thermal motion of colloidal particles is influenced by boundary condition choices.

Conclusions:

• Bounce-back boundary conditions are essential for accurate MPCD simulations of colloids.
• MPCD simulations can be extended to implement partial slip boundary conditions.
• The findings provide guidelines for improving the fidelity of colloidal simulations.