A candidate mechanism for exciting sound during bubble coalescence

Abstract

Coalescing bubbles are known to produce a pulse of sound at the moment of coalescence, but the mechanism driving the sound production is uncertain. A candidate mechanism for the acoustic forcing is the rapid increase in the bubble volume, as the neck of air joining the two parent bubbles expands. A simple model is presented here for the volume forcing caused by the coalescence dynamics, and its predictions are tested against the available data. The model predicts the right order of magnitude for the acoustic amplitude, and the predicted amplitudes also scale correctly with the radius of the smaller parent bubble.

Passive acoustic quantification of gas fluxes during controlled gas release experiments

“…In practical uses for today's industrial leaks (in order to assess of gas leaks levels for oil and gas facilities) or high volume methane seeps (to investigate temporal variability over long periods of time), estimates of gas flux to within an order of magnitude are usually useful. Better characterization of emission mechanisms (Deane and Stokes, 2008;Deane and Czerski, 2008;Czerski, 2011) will improve the accuracy of the method in line with the deployment of new methods for increasingly accurate estimates of the void fraction of gas bubbles beneath the seabed (Leighton and Robb, 2008;Leighton, 2007a,b).…”

“…and the mechanisms of excitation (Deane and Czerski, 2008;Czerski, 2011;Czerski and Deane, 2011), when even reshaping or reorientation of a given nozzle can in some circumstances change the acoustic emission. Therefore it was important to undertake a validation exercise to investigate to what extent the inversion scheme described here allows useful gas flux estimates to be made before the developing theoretical basis for bubble excitation mechanics can progress to a level to use in this model.…”

Toward animating water with complex acoustic bubbles

“…However, estimates of the Laplace pressure jump, as well as hydrostatic pressure and shape mode coupling effects, show that they represent a minor (< 10%) amount of the total forcing [Pumphrey and Ffowcs Williams 1990]. A recent set of papers from Deane and Czerski [2008;2011;2011] propose a family of models based on neck collapse (for entrainment and splitting events) and neck expansion (for merging events) where surface tension effects account for the majority of forcing (summarized in Figure 12).…”

“…Bubble forcing models are devised to account for bubble excitations during surface entrainment, but also subsequent splitting and merging events. While prior works considered only Laplace pressure-jump forcing at entrainment, we leverage improved models of detailed surfacetension modeling (recently proposed by Deane and Czerski [2008;2011;2011]). To model bubble popping sounds, we describe a Helmholtz resonator model.…”

A note on the critical gap of bubble coalescence during foaming process: A diffuse-interface modeling

“…Sprittles simulated coalescence numerically and com-pared the results with experimental data [14]. Czerski investigated sound during bubble coalescence [15]. Case et al employed an electrical method to study the coalescence of two low-viscosity droplets at early times [16,17].…”