The gravity-driven migration of N ≥ 1 bubble(s) near a free surface is addressed within the assumption of negligible inertial effects by solving a boundary-integral equation at each time and assuming axisymmetric free surface and bubble(s) with axis of revolution aligned with the gravity. The implemented boundary element method permits one to accurately invert at a reasonable cpu time cost the ...

The breakup of a millimetre size buoyantly rising bubble encountering a horizontal plane turbulent jet is experimentally investigated using high-speed shadowgraphy and acoustic techniques. The bubble diameter to jet height ratio is 0.75 and the jet height based Reynolds number is 4000. The high-speed imaging was recorded at 7 kHz simultaneous with hydrophone output at 100 kHz. Bubble breakup ev...

Mass transfer in gas liquid systems depends on the contact between the entities in which the gas phase is dispersed into the liquid, the bubbles, and the surrounding liquid. Further knowledge of the hydrodynamics of the growing and rising bubbles under mass transfer conditions will help in the understanding of the mass transfer process in bubble columns and in the design of the equipment.

Closure relations are presented for the lift coe.cient for ordered arrays of 2-D and 3-D bubbles at various bubble volume fractions. These were determined via lattice Boltzmann simulations of bubble rise in periodic boxes, where the bubbles were also subjected to shear. The single-bubble lift coe.cient, determined by low-shear computational experiments, varies in a systematic manner with the as...

China’s decade-long housing boom looks nothing short of a gigantic bubble familiar to many countries: In big cities the price-to-income ratio reached 30 to 1 and the vacancy rate stood at 30% or above. This paper provides a theoretical framework to shed light on the causes and consequences of the great housing boom in China. We argue that the boom could be a rational bubble rooted in China’s un...

The effect of soluble surfactants on the unsteady motion and deformation of a bubble rising in an otherwise quiescent liquid contained in an axisymmetric tube is computationally studied by using a finite-difference/front-tracking method. The unsteady incompressible flow equations are solved fully coupled with the evolution equations of bulk and interfacial surfactant concentrations. The surface...

The proper interpretation of bubble rising in a liquid column is critical in the investigation of the waterevapour two phase flow and heat transfer. In this paper, the bubble behaviours are studied using the combination of Level Set Method (LSM) and moving mesh method in a collocated grid. Level set method is used to track the interface of the bubble, which has many advantages over other interf...

The rise and impact of bubbles at an initially flat but deformable liquid-air interface in ultraclean liquid systems are modelled by taking into account the buoyancy force, hydrodynamic drag, inertial added mass effect and drainage of the thin film between the bubble and the interface. The bubble-surface interaction is analyzed using lubrication theory that allows for both bubble and surface de...

The Chandra X-ray Observatory is finding a surprisingly large number of cavities in the X-ray emitting intracluster medium (ICM), produced by the release of radio plasma from active galactic nuclei. In this Letter, we present simple analytic formulae for the evolution of the X-ray deficit and for the radio spectrum of a buoyantly rising bubble. The aim of this work is to provide a theoretical f...

A planar laser-induced fluorescence (PLIF) technique for visualizing gas–liquid mass transfer and wake structure of rising gas bubbles is described. The method uses an aqueous solution of the pH-sensitive dye Naphthofluorescein and CO2 as a tracer gas. It features a high spatial resolution and frame rates of up to 500 Hz, providing the ability to capture cinematographic image sequences. By stee...