Coalescence Deformation of Bubble Pairs Generated from Twin Nozzles in CMC Solutions

Abstract

A coupled level-set/volume-of-fluid method, under the consideration of the rheological characteristics of a fluid, is employed to investigate numerical coalescence deformation of bubble pairs generated at two adjacent nozzles in carboxymethyl cellulose aqueous solutions. The satisfactory agreement between numerical results and experimental measurements proves the validity of this approach in predicting the surface evolution of bubbles. Simulated results show that the bubble coalescence process involves four stages of independent growth, rapid mergence, radial expansion, and vertical stretching. The various effects of surfactant concentration, gas flow rate, nozzle spacing, and nozzle diameter on the aspect ratio depend greatly on each coalescence period.

Coalescence of Two Equal-Sized Bubbles with Air Injection

“…We carried out the numerical simulations using the self-developed Multi-interfaces Advection and Reconstruction Solver (MARS) based on the volume-of-fluid (VOF) method. , The VOF method has demonstrated its capability for capturing the dynamics of bubble formation and subsequent coalescence processes. , …”

“…29,30 The VOF method has demonstrated its capability for capturing the dynamics of bubble formation and subsequent coalescence processes. 26,27 2.2.1. Governing Equations.…”

“…In the presence of continuous air injection, numerical studies indicate the vortex formation and interaction around two growing bubbles before they contact. , This implies that the flow field affected by bubble growth might influence subsequent coalescence behaviors. Fan et al carried out numerical simulations on the bubble formation and coalescence processes of bubble pairs formed at adjacent nozzles. Their findings highlight that the effects of surfactant concentration, gas flow rate, nozzle size, and spacing on the bubble’s deformation vary across different periods, i.e., independent growth, rapid coalescence, radial expansion, and vertical stretching.…”

Coalescence Characteristics of Side‐by‐Side Growing Bubbles in Carboxymethyl Cellulose Solutions

“…The measurement setup consists of a bubble coalescence system and an image collection system. A detailed description of the setup and its components can be found in our previous work . The most relevant characteristics of the experimental setup is that it allows small bubble pairs to be always produced periodically at the given gas volume flow rate controlled accurately by the syringe pump.…”

“…Liu et al numerically investigated both coalescence and breakup regimes of multiple parallel bubbles in a power‐law fluid. Recently, Fan et al have simulated the coalescence process of bubble pairs at two adjacent nozzles in CMC solutions by using the combined level‐set and volume‐of‐fluid method. Zhu et al numerically considered the generation and coalescence of bubbles from two parallel nozzles and proposed two correlations for predicting the critical nozzle intervals for the transition.…”