Intense sound waves exert a steady (DC) force on objects and interfaces — acoustic radiation pressure. This enables acoustic levitation, tweezers, and streaming. Based on the Langevin and Gor'kov theories.
Acoustic Trap Simulation
← Emitter (transducer)Reflector →
Setup Mode
Radiation force F: -- nN
Gor'kov potential U: -- pJ
Levitation SPL: -- dB
U = 4πr³[f₁p²/3ρ₀c² − f₂ρ₀v²/2]
F = −∇U
f₁ = 1 − κₚ/κ₀, f₂ = 2(ρₚ−ρ₀)/(2ρₚ+ρ₀)
Gor'kov (1962) showed particles are trapped at pressure nodes if more compressible than fluid, or at pressure antinodes if denser. Acoustic levitation by Whymark (1975) levitates particles in air against gravity using ~150+ dB standing waves.
Gor'kov Potential Landscape
The Gor'kov potential determines trap locations. Minima (dark) are stable traps. Drag the particle on the simulation above to see it snap back to the trap.