Critical corrections to formulations of nonlinear energy dissipation of ultrasonically excited bubbles and a unifying parameter to asses and enhance bubble activity in applications

TL;DR

This paper critically revises the formulations of nonlinear energy dissipation in ultrasonically excited bubbles, incorporating radiation damping effects, and introduces a unifying parameter to evaluate bubble activity in various applications.

Contribution

It provides corrected formulations for nonlinear bubble energy dissipation including radiation damping and proposes a new parameter to assess bubble activity effectiveness.

Findings

Corrected the nonlinear energy dissipation formulas for bubbles.

Highlighted the significance of radiation damping at high pressures.

Introduced a unifying parameter to evaluate bubble activity.

Abstract

Nonlinear oscillations of bubbles can significantly increase the attenuation of the host media. Optimization of bubble related applications needs a realistic estimation of the medium attenuation and bubble activity. A correct estimation of the wave attenuation in bubbly media requires an accurate estimation of the power dissipated by nonlinear oscillations of bubbles. Pioneering work of Louisnard \cite{1} meticulously derived the nonlinear energy terms for viscous and thermal damping; however, radiation damping arising from the compressibility of the liquid was neglected. Jamshidi $\&$ Brenner \cite{2} have considered the effects of the compressibility of the liquid and showed that damping due to radiation becomes the most significant factor at pressures above the blake threshold. Despite the improvement in their formulation; however, the radiation damping term estimates non-physical values for some frequency and pressure regions including near resonance oscillations. Thus, the new terms arising from the compressibility of the liquid needs critical assessment. In this work, we provide critical corrections to the present formulations. Importance of the new corrections are highlighted by the scattering to damping ratio (STDR). We then introduce a unifying parameter to assess the efficacy of applications; this parameter is defined as the multiplication of maximum scattered pressure by STDR.