Minimal model for acoustic forces on Brownian particles.

Area of Science:

• Computational physics
• Fluid dynamics
• Acoustic particle manipulation

Background:

• Inertial coupling (IC) is a method for simulating particle-fluid interactions.
• Existing IC methods have limitations in resolving radiation forces for particles with arbitrary acoustic properties.
• Thermal fluctuations and micro-scale phenomena require accurate modeling in particle simulations.

Purpose of the Study:

• To generalize the inertial coupling (IC) method for arbitrary acoustic contrast factors.
• To accurately resolve radiation forces on small particles in fluid simulations.
• To enable efficient, large-scale simulations of particle dynamics.

Main Methods:

• A generalized Eulerian-Lagrangian approach using the finite volume method for fluid equations.
• Incorporation of thermal fluctuations via Landau-Lifshitz fluid description.
• Extension of particle kernel functionality to handle arbitrary particle compressibility and enforce a no-slip constraint for instantaneous coupling.

Main Results:

• The generalized IC method accurately reproduces monopolar (compressibility) and dipolar (mass) contributions to acoustic forces.
• The method captures fast, nonlinear effects in particle-radiation force interactions.
• Simulations with up to 10^4 particles are feasible on a standard GPU due to low computational cost.

Conclusions:

• The generalized IC method provides a robust and efficient tool for simulating acoustic radiation forces on particles.
• This advancement facilitates the study of micro-scale particle dynamics in complex fluid environments.
• The computational efficiency allows for unprecedented large-scale simulations of particle-laden flows.