Acoustic radiation force on a heated spherical particle in a fluid including scattering and microstreaming from a standing ultrasound wave

TL;DR

This paper derives analytical expressions for the acoustic radiation force on a heated spherical particle in a fluid, accounting for scattering and microstreaming effects, revealing how temperature-induced sound speed changes can reverse force direction.

Contribution

It introduces a comprehensive model including particle heating, scattering, and microstreaming effects to analyze the acoustic radiation force on particles.

Findings

Temperature gradients significantly alter the force via sound speed changes.

Particle heating can reverse the force direction with minimal temperature increase.

Microstreaming patterns are sensitive to particle heating and fluid properties.

Abstract

Analytical expressions are derived for the time-averaged, quasi-steady, acoustic radiation force on a heated, spherical, elastic, solid microparticle suspended in a fluid and located in an axisymmetric incident acoustic wave. The heating is assumed to be spherically symmetric, and the effects of particle vibrations, sound scattering, and acoustic microstreaming are included in the calculations of the acoustic radiation force. It is found that changes in the speed of sound of the fluid due to temperature gradients can significantly change the force on the particle, particularly through perturbations to the microstreaming pattern surrounding the particle. For some fluid-solid combinations, the effects of particle heating even reverse the direction of the force on the particle for a temperature increase at the particle surface as small as 1 K.