Acoustic Streaming and Its Suppression in Inhomogeneous Fluids

Area of Science:

• Fluid dynamics
• Acoustics
• Nonlinear phenomena

Background:

• Acoustic streaming, or Rayleigh streaming, typically arises from boundary layer dissipation in homogeneous fluids.
• Inhomogeneous fluids introduce complexities not fully understood in acoustic streaming phenomena.

Purpose of the Study:

• To investigate the effects of fluid inhomogeneity on boundary-driven acoustic streaming.
• To identify and characterize novel forces influencing acoustic streaming in variable density and compressibility fluids.

Main Methods:

• Theoretical modeling of acoustic streaming in inhomogeneous media.
• Numerical simulations to analyze fluid behavior under acoustic forcing.
• Experimental validation using ultrasound in microfluidic devices with inhomogeneous solutions.

Main Results:

• Identified a nondissipative force density acting in inhomogeneous fluids.
• Demonstrated that this force stabilizes specific inhomogeneity configurations.
• Observed significant alteration and suppression of acoustic streaming flows.

Conclusions:

• Fluid inhomogeneity introduces stabilizing forces that modify acoustic streaming.
• The findings challenge traditional understanding of Rayleigh streaming in uniform media.
• This work provides a foundation for controlling acoustic streaming in complex fluids.