Comparing methods for the modelling of boundary-driven streaming in acoustofluidic devices

Area of Science:

• Fluid dynamics
• Acoustics
• Numerical simulation

Background:

• Acoustic streaming flows are crucial for acoustofluidic manipulation devices.
• Accurate numerical simulations are needed to understand and optimize these devices.
• Boundary-driven streaming flows present unique modeling challenges.

Purpose of the Study:

• To compare two perturbation theory-based numerical methods for modeling boundary-driven acoustic streaming flows.
• To assess the viability and applicability of the Reynolds stress and limiting velocity methods.
• To provide guidance for selecting appropriate numerical methods in acoustofluidics.

Main Methods:

• Reynolds stress method: Predicts streaming fields from driving terms, resolving inner and outer flow fields.
• Limiting velocity method: Solves outer streaming fields using 'limiting velocities' as boundary conditions, ignoring the acoustic boundary layer.
• Comparison of computational efficiency and accuracy for both 2D and 3D models.

Main Results:

• Reynolds stress method effectively demonstrates driving mechanisms but is computationally limited to 2D models.
• Limiting velocity method is computationally efficient for 3D outer flows when channel curvature is large compared to the acoustic boundary layer thickness.
• The limiting velocity method requires channel scales > 100 times the acoustic boundary layer thickness for ~5% accuracy.

Conclusions:

• Both numerical methods are viable for modeling acoustic streaming flows in acoustofluidics.
• The choice of method depends on the specific application, dimensionality, and required accuracy.
• This comparison aids researchers in selecting optimal methods for designing acoustofluidic particle manipulation devices.