Pseudo-turbulence in two-dimensional buoyancy driven bubbly flows: a DNS study

TL;DR

This DNS study explores how buoyancy-driven bubbles in 2D flows exhibit different energy scaling regimes, including inverse cascades, unaffected by bubble density ratio or coalescence.

Contribution

The paper introduces a detailed DNS analysis of 2D buoyancy-driven bubbly flows, revealing the influence of the Galilei number on energy spectra and cascade behavior.

Findings

High Galilei numbers lead to inverse energy cascades.

Density ratio and coalescence do not affect scaling regimes.

Spectral properties are governed by the Galilei number.

Abstract

We present a direct numerical simulation (DNS) study of buoyancy driven bubbly flows in two-dimensions. We employ volume of fluid (VOF) method to track the bubble interface. To investigate spectral properties of the flow, we derive the scale-by-scale energy budget equation. We show that the Galilei number (Ga) controls different scaling regimes in the energy spectrum. For high Galilei numbers, we find the presence of an inverse energy cascade. Our study indicates that the density ratio of the bubble with the ambient fluid or the presence of coalescence between the bubbles does not alter the scaling behaviour.