Abstract

Abstract

The memory of the bubbles

Javier Rodríguez Rodríguez

Carlos III University of Madrid, Spain Abstract

Two micrometric bubbles translating as a result of an acoustic pulse. Duration of the trajectory (in white) about 200 microseconds (left) and numerical simulations of the flow and concentration field around a CO2 bubble that first grows and then dissolves in a liquid (right).

Although seemly different, the translational motion of a bubble in an acoustic field and the growth or dissolution of a bubble in the surrounding liquid share a common physical effect: diffusion. Indeed, diffusion contributes to the transport of vorticity in the first case and of the gas exchanged by the bubble in the second. In many applications, the temporal term in the diffusion-advection transport equations can be safely neglected, which greatly simplifies the analysis of these problems (otherwise the analysis involves solving integro-differential equations!). However, there are situations in which neglecting these transient effects results in an unsatisfactory description of the flow. Here, we will explore from a theoretical and experimental point of view when and how to take into account memory effects, in a relatively painless way, in the two situations mentioned above. We will show how including these terms, even in an approximate way, significantly improves the agreement between theory and experiments.

References:

E Igualada-Villodre, A Medina-Palomo, P Vega-Martínez, J Rodríguez-Rodríguez, Transient effects in the translation of bubbles insonated with acoustic pulses of finite duration, Journal of Fluid Mechanics 836, 649-693, 2018

P Peñas-López, MA Parrales, J Rodríguez-Rodríguez, D Van Der Meer, The history effect in bubble growth and dissolution. Part 1. Theory, Journal of fluid mechanics 800, 180-212, 2016

P Peñas-López, ÁM Soto, MA Parrales, D Van Der Meer, D Lohse, J Rodríguez-Rodríguez, The history effect on bubble growth and dissolution. Part 2. Experiments and simulations of a spherical bubble attached to a horizontal flat plate, Journal of fluid mechanics 820, 479-510, 2017