Bubble Formation In Water Research Articles

Bubble formation in water with magnetite nanoparticles during microwave irradiation

In this study, bubble formation phenomena in the dispersion medium of magnetite nanoparticle in water during microwave irradiation were investigated. From the experimental results, it was found that under microwave treatment, the maximum bubble size was greatly influenced by the suspension density at a given temperature due to the distribution of microwave energy to the particles itself or the liquid-air interface of bubbles around the particle. Nanoparticles in the dispersion medium were also found to play a key role in achieving stable nucleation of bubbles on particles surface. Smaller bubble sizes were produced at higher suspension density. Microwave power also has a positive impact on the maximum bubble size especially at low suspension density. Moreover, particle material having dielectric constant property was also found to be an important factor for bubble size during microwave irradiation. From these results and findings, it is envisaged that bubble size can be controlled by the presence of nanoparticle and microwave irradiation.

Cavitation bubble dynamics during pulsed laser ablation of a metallic glass in water

We report a cavitation bubble formation in water induced by nanosecond pulsed laser ablation of a Zr-based (Vitreloy 1) bulk metallic glass target. Only the first bubble occurs due to an explosive-boiling-type ablation of the target. A theoretical model is developed to quantitatively describe the bubble nucleation and its initial growth. The results demonstrate that the laser-induced plasma can induce the nucleation of the bubble. Furthermore, it is revealed that the initial bubble growth is approximately adiabatic and inertial, obeying the Rayleigh–Plesset theory, albeit the significant ablation. This work sheds insight into the mechanics of water-confined laser ablation of metallic glasses, and provides guidance for synthesizing amorphous nanoparticles.

Observation of bubble formation in water during microwave irradiation by dynamic light scattering

A microwave reactor was designed for in situ observation of nano- and micro-bubbles, and size profiles during and after irradiation were measured with respect to irradiation power and time. Bubble formation in water during irradiation was observed even at temperatures below the boiling point of water. The maximum size strongly depended on radiation power and time, even at a given temperature. Nano-particles in the dispersion medium were found to play an important role in achieving more stable nucleation of bubbles around particles, and stable size distributions were obtained from clear autocorrelation by a dynamic light scattering system. Moreover, a combination of microwave induction heating and the addition of nano-particles to the dispersion medium can prevent heterogeneous nucleation of bubbles on the cell wall. Quantitative nano-bubble size profiles obtained by in situ observation provide useful information regarding microwave-based industrial processes for nano-particle production.

Bubble formation in water with addition of a hydrophobic solute.

We show that phase separation can occur in a one-component liquid outside its coexistence curve (CX) with addition of a small amount of a solute. The solute concentration at the transition decreases with increasing the difference of the solvation chemical potential between liquid and gas. As a typical bubble-forming solute, we consider O2 in ambient liquid water, which exhibits mild hydrophobicity and its critical temperature is lower than that of water. Such a solute can be expelled from the liquid to form gaseous domains while the surrounding liquid pressure is higher than the saturated vapor pressure p cx. This solute-induced bubble formation is a first-order transition in bulk and on a partially dried wall, while a gas film grows continuously on a completely dried wall. We set up a bubble free energy ΔG for bulk and surface bubbles with a small volume fraction ϕ. It becomes a function of the bubble radius R under the Laplace pressure balance. Then, for sufficiently large solute densities above a threshold, ΔG exhibits a local maximum at a critical radius and a minimum at an equilibrium radius. We also examine solute-induced nucleation taking place outside CX, where bubbles larger than the critical radius grow until attainment of equilibrium.

Spherical gold nanoparticles and core/shell microparticles under intense femtosecond laser excitation: relaxation dynamics of gold nanoparticles and nanostructuring of borosilicate glass using microparticles

This paper reports surface nanostructuring of borosilicate glass covered with a water layer and the production of diameter pits using core/shell microparticles under excitation with pulses using the optical scheme of an inverted microscope with a objective. We compare the thresholds for hole formation in glass with the use of and uncoated microparticles. The threshold is for and for microparticles, which coincides with the threshold for nanostructuring by a focused femtosecond pulse without microparticles: . Femtosecond pump – probe spectroscopy has been used to study the relaxation dynamics of laser pulse energy absorbed in a Au nanoparticle and the dynamics of energy dissipation to the ambient medium. The threshold for cavitation bubble formation in water with has been determined to be , which is a factor of 30 lower than the bubble formation threshold in the case of uncoated microparticles.

Bubble formation induced by nanosecond laser ablation in water and its diagnosis by optical transmission technique

In this paper, bubble formation and ablation rate in laser ablation of a thin-film aluminum target are studied. The target was an aluminum thin-film coated on a quartz substrate and interacted by a nanosecond Nd:YAG laser beam in ambient air and distilled water. Measuring optical transmission of a He-Ne beam through the ablation region shows that the ablation rate in water is higher than that in ambient air. The results also show that an initial peak appears in the transmission signal which is an evi- dence for bubble formation in water. Analyzing the data is useful for monitoring the bubble formation in water and relatively estimating the ablation rate.

Planar Simulation of Bubble Growth in Film Boiling in Near-Critical Water Using a Variant of the VOF Method

A planar simulation of film boiling and bubble formation in water at 373°C, 219 bar on an isothermal horizontal surface was performed by using a volume of fluid (VOF) based interface tracking method. The complete Navier-Stokes equations and thermal energy equations were solved in conjunction with a interface mass transfer model. The numerical method takes into account the effect of temperature on the transportive thermal properties (thermal conductivity and specific heat) of vapor, effects of surface tension, the interface mass transfer and the corresponding latent heat. The computations provided a good insight into film boiling yielding quantitative information on unsteady periodic bubble release patterns and on the spatially and temporally varying film thickness. The computations also predicted the transport coefficients on the horizontal surface, which were greatly influenced by the variations in fluid properties, compared to calculations with constant properties.

Erbium: yttrium-aluminum-garnet laser induced vapor bubbles as a function of the quartz fiber tip geometry.

The use of modern erbium: yttrium-aluminum-garnet (YAG) laser systems in opthalmic microsurgery requires a precise knowledge of the size and dynamics of the laser induced vapor bubbles. The aim of this work was to clarify the possibilities of controlling the vapor bubble shape and size by using an optimized fiber tip geometry for various ophthalmic applications with the erbium: YAG laser. The mid-infrared radiation of free-running erbium: YAG laser was coupled optically into means of different low OH(-) quartz fiber tips to investigate the vapor bubble formation in water by high-speed photography. The core diameter of four fiber tips ranged from 200 up to 940 microm. Fourteen fiber tips were polished at an angle graduated from 10 degrees to 70 degrees over the full core diameter (seven fiber tips) and over the half core diameter (seven fiber tips). Three fiber tips were produced to have a curvature at the distal end with curvature radii of 160, 230, and 420 microm. The shape as well as the size of erbium: YAG laser induced vapor bubbles can be controlled systematically by using adequate fiber tip geometries. In detail, the used different angles and curvatures demonstrate that the propagation direction of the vapor bubbles can be estimated by optical modeling considering Snell's law and the Fresnel laws at a quartz-air boundary. Beside this, the size of a vapor bubble can be predetermined by choosing ideal fiber tip geometries to reduce or increase the radiant exposure at the distal end of the quartz fiber tip. The good possibility of controlling the shape and size of vapor bubbles offers a wider range of new applications, especially in ophthalmic microsurgery such as erbium YAG laser vitrectomy.

Frequency of bubble formation in water and liquid iron

In the present work a device for measuring the frequency of bubble formation was developed and tested in water and liquid iron. Using a pressure sensor, the pressure difference induced by bubble formation from a nozzle inserted in the liquid phase is registered and analysed by a frequency analyser. The test results showed a good reliability and accuracy of the device in comparison with the bubble formation theory.

Bubble Formation in Water at Smooth Hydrophobic Surfaces

It has frequently been assumed that hydrophobic surfaces serve as initiation points for in vivo bubble formation; yet, no studies have demonstrated that this relationship actually exists. In the present investigation, the concept of spontaneous bubble formation at smooth hydrophobic surfaces has been examined. Smooth polystyrene and silica beads, each with either hydrophilic or hydrophobic surfaces, were examined for their ability to generate bubbles in distilled water at gas supersaturations ranging from 5 to 125 atm N2 at room temperature (24-27°C). Few bubbles occurred in suspensions exposed to gas supersaturations in the range from 5 to 50 atm N2. Even at higher gas supersaturations, which approached the spontaneous nucleation threshold of bulk water, relatively few bubbles were formed in these suspensions. Clearly, these surfaces did not induce gas bubble formation, even at high gas supersaturations. This suggests that the cohesive forces between the water and hydrophobic particles were not weakened to the point of rupture, so that these interfaces did not provide bubble nucleation sites. This investigation demonstrated that smooth surfaces, whether hydrophilic or hydrophobic in nature, do not facilitate in vitro gas bubble formation by dissolved gas in water.

Skins of varying permeability: A stabilization mechanism for gas cavitation nuclei

Numerous experiments suggest that bubble formation in water is initiated by preexisting gas nuclei. This is unexpected since gas phases larger than the order of 1 μm in radius ought to rise to the surface of a standing liquid, whereas smaller ones should dissolve rapidly via the outward diffusion of gas that results from surface tension. Several mechanisms for stabilizing gas nuclei have been proposed, but in each case there is experimental evidence to the contrary. In this article, a model is investigated in which stability is maintained by surface-active skins of varying gas permeability. Data on ultrasonic cavitation and on bubble formation by counter-diffusion indicate that such skins, if they exist, must be initially permeable. Quantitative comparisons with bubble counts obtained recently from supersaturated gelatin lead to the further conclusion that nuclear skins become effectively impermeable if the static pressure is raised rapidly by a sufficiently large amount. The surface area, length, and energy per skin molecule deduced from these comparisons are remarkably similar to those of known surfactants, such as lung extract, lecithin, and oleyl alcohol.