Bubble Content Research Articles

Numerical simulation of bubble plumes and an analysis of their seismic attributes

To study the bubble plume’s seismic response characteristics, the model of a plume water body has been built in this article using the bubble-contained medium acoustic velocity model and the stochastic medium theory based on an analysis of both the acoustic characteristics of a bubble-contained water body and the actual features of a plume. The finite difference method is used for forward modelling, and the single-shot seismic record exhibits the characteristics of a scattered wave field generated by a plume. A meaningful conclusion is obtained by extracting seismic attributes from the pre-stack shot gather record of a plume. The values of the amplitude-related seismic attributes increase greatly as the bubble content goes up, and changes in bubble radius will not cause seismic attributes to change, which is primarily observed because the bubble content has a strong impact on the plume’s acoustic velocity, while the bubble radius has a weak impact on the acoustic velocity. The above conclusion provides a theoretical reference for identifying hydrate plumes using seismic methods and contributes to further study on hydrate decomposition and migration, as well as on distribution of the methane bubble in seawater.

Acoustics of a Polydisperse Vapor–Gas Bubbles-Laden Liquid

A mathematical model is presented that determines the propagation of acoustic waves in a liquid containing polydisperse vapor–gas bubbles with account for mass transfer processes. A system of integrodifferential equations of a disturbed motion of a two-phase mixture is written, and a dispersion relation is obtained. A general expression for the equilibrium velocity of sound has been found for a vapor–gas liquid mixture, and the influence of vapor concentration and of the volume content of bubbles on the value of the equilibrium velocity of sound has been analyzed. In particular cases, expressions of the equilibrium velocity of sound are presented for gas–liquid and vapor–liquid mixtures, and satisfactory agreement of the obtained values with the familiar experimental data has been obtained. The results of comparison of the dispersion curves of phase velocity and of the attenuation coefficient for a mixture of water with vapor–air bubbles at different values of the initial concentration of vapor in bubbles are given.

Rheological controls on the eruption potential and style of an andesite volcano: A case study from Mt. Ruapehu, New Zealand

The evolving magma rheology of three recent Ruapehu eruptions (1969, 1977, and 1995) is estimated using a combination of thermodynamic models and rheological calculations, supported by textural observations of the erupted scoria. We use a well-established thermodynamic model to determine the composition of these representative Ruapehu magmas from 300MPa to ∼30MPa. The outputs of the model provide the changing crystal and bubble content in a closed system (assuming no gas loss), as well as the fractionating melt compositions. We calculate the melt viscosity, and the effect of bubbles and crystals, to quantify the rheology of the magma during ascent (under assumed equilibrium conditions). The moderately high phenocryst content of Ruapehu scoria (∼30%) means that only a small amount of additional microlite crystallisation (∼5%) would result in a yield strength, which may lead the magma to stall. However, if the strain rates are high enough, more crystallisation would be possible without developing a yield stress. This suggests that microlite-rich magmas are almost certain to stall unless they encounter significant fluid addition from a source such as a hydrothermal system, groundwater, or surface water (i.e., Ruapehu's Crater Lake).Ruapehu magmas are initially H2O-undersaturated and as a consequence, crystallisation and bubble growth were suppressed until the magma achieved saturation, at ∼100 to 50MPa. From this analysis, we suggest that Ruapehu magmas are more likely to erupt compared to magmas of a similar composition that are H2O-saturated. This partly explains the regular, albeit small-volume eruptions at Ruapehu and the propensity for phreatomagmatic eruptions when the magma:water ratio is low.

Mathematical analysis of the effects of operating conditions and rheological behaviour of reaction medium on biodiesel synthesis under ultrasound irradiation

Ultrasound assisted transesterification has recently been introduced as an effective technology for biodiesel synthesis. However, the behaviour of micro bubbles under ultrasound is affected by operating conditions or rheological properties of reaction mixtures. This paper aims at investigating the changes of micro bubbles characteristics when operating conditions or rheological behaviour of the reaction medium are altered. The mechanistic simulation of micro bubbles was combined with the CFD simulation of reaction mixture to achieve the aims of this work. Continuity and momentum equations of Keller-Miksis model were employed along with reaction, mass and energy balances to simulate different characteristics of micro bubbles such as temperature, pressure, oscillation velocity, maximum radius of micro bubble, equilibrium state of bubble content, diffusion rates of reaction compounds towards bubbles and reaction within bubbles. It was found that among different combinations of reaction temperature, reactants ratio and intensity of ultrasound irradiation, the last one played the most important role. Radius, internal temperature and pressure of bubbles significantly increased with power amplitude due to stronger expansion and greater energy accumulation. At the same time, increase in reaction temperature and alcohol concentration made the bubbles characteristics rather moderate. It was also found that the growth of bubbles radius was reduced by about 4 times as the reaction progressed and the reaction mixture became more viscous and dense. The maximum internal temperature and pressure decreased by about 178K and 220bar due to moderate expansion of bubbles. Oscillation velocity was also restricted in this situation.

Interfacial Stabilization of Fiber-Laden Foams with Carboxymethylated Lignin toward Strong Nonwoven Networks.

Wet foams were produced via agitation and compressed air bubbling of aqueous solutions of carboxymethylated lignin (CML). Bubble size and distribution were assessed in situ via optical microscopy. Foamability, bubble collapse rate, and foam stability (half-life time) were analyzed as a function of CML concentration, temperature, pH, and air content. Dynamic changes of the CML liquid foam were monitored by light transmission and backscattering. Cellulosic fibers of different aspect ratios (long pine fibers and short birch fibers) were suspended under agitation by the liquid foams (0.6% CML in the aqueous phase) with an air (bubble) content as high as 75% in volume. Remarkably, the half-life time of fiber-laden CML foams was 10-fold higher than that of the corresponding fiber-free liquid foam. Such lignin-based foams were demonstrated, after dewatering, as a precursor for the synthesis of nonwoven, layered structures. The resulting fiber networks (paper), obtained here for the first time with lignin-based foams, were characterized for pore size distribution, lignin retention, morphology, and physical-mechanical properties (network formation quality, density, air permeability, surface roughness, and tensile and internal bond strengths). The results were compared against structures obtained from foams stabilized with an anionic surfactant (SDS) as well as those from foam-free, water-based web-laying. Remarkably, compared to SDS, the foam-formed materials produced with CML displayed better bonding and tensile strengths. Overall, CML-based foams were found to be suitable carriers of cellulosic fibers and have opened the possibility for integrating fully biobased systems in foam-forming. This is an emerging option to increase the effective solids content in the system without compromising the quality of formed nonwoven materials while achieving reductions in water and energy consumption.

Models for viscosity and shear localization in bubble-rich magmas

Bubble content influences magma rheology and, thus, styles of volcanic eruption. Increasing magma vesicularity affects the bulk viscosity of the bubble-melt suspension and has the potential to promote non-Newtonian behavior in the form of shear localization or brittle failure. Here, we present a series of high temperature uniaxial deformation experiments designed to investigate the effect of bubbles on the magma bulk viscosity. The starting materials are cores of natural rhyolitic obsidian synthesized to have variable vesicularity (ϕ=0–66%). The foamed cores were deformed isothermally (T=750°C) at atmospheric conditions using a high-temperature uniaxial press under constant displacement rates (strain rates between 0.5–1×10−4 s−1) and to total strains of 10–40%. The viscosity of the bubble-free melt (η0) was measured by micropenetration and parallel plate methods to establish a baseline for experiments on the vesicle rich cores. At the experimental conditions, rising vesicle content produces a marked decrease in bulk viscosity that is best described by a two-parameter empirical equation: log10⁡ηBulk=log10⁡η0−1.47[ϕ/(1−ϕ)]0.48. Our parameterization of the bubble-melt rheology is combined with Maxwell relaxation theory to map the potential onset of non-Newtonian behavior (shear localization) in magmas as a function of melt viscosity, vesicularity, and strain rate. For low degrees of strain (i.e. as in our study), the rheological properties of vesicular magmas under different flow types (pure vs. simple shear) are indistinguishable. For high strain or strain rates where simple and pure shear viscosity values may diverge, our model represents a maximum boundary condition. Vesicular magmas can behave as non-Newtonian fluids at lower strain rates than unvesiculated melts, thereby, promoting shear localization and (explosive or non-explosive) magma fragmentation. The extent of shear localization in magma influences outgassing efficiency, thereby, affecting magma ascent and the potential for explosivity.

Slag conditions in electrosmelting: A review

The literature on the foaming of electrofurnace slag is reviewed. On that basis, recommendations for improvement in slag foaming are formulated. Inconsistencies in the published data are noted, and some principles are elaborated. It is evident that two key factors have been ignored in the existing research: the temperature of the slag; and its content of small gas bubbles.

Features of the dynamics of postdetonation waves

We present the results of numerical investigations of the parameters of postdetonation waves forming at a passage from the zone occupied with a bubbly liquid formed by the detonation wave to a zone filled with a liquid without bubbles. The dependence of the pressure amplitude of detonation waves and postdetonation waves on the gas volumetric content of bubbles has been studied. A possibility of the detonation transfer through the layer of a bubble-free liquid separating the regions of the bubbly liquid has been shown, the map of possible situations at the detonation transfer through the layer of this liquid has been presented.

MATHEMATICAL MODELING OF LADLE FURNACE THERMAL CONDITIONS DURING GAS-BUBBLE MELT BLOWING. REPORT IV

A significant effect on heat transfer during copper fire refining in a ladle furnace is caused not only by forming and motion of gas bubbles in a melt, but also by the volume content of gas bubbles. The presented mathematical model analyzes the effect of melt gas fullness during blowing and gas temperature under the cover on an average temperature of the melt being refined.

BUBBLE BURSTING AT A FREE SURFACE IN A CLOSED DOMAIN

When a charge explodes underwater near a free surface, a bubble would be generated and the surface pushed up very high. Experiments have shown that the motion of the spike lags a lot behind the bubble motion. Many studies only focus on the nonlinear interaction between the bubble and free surface while the water waves afterward is mainly studied based on the linear theory. The nonlinear motion of the water wave after the bubble pulsation is seldom studied. In this study, we concerns the interaction between underwater explosion generated bubble and a free surface and its bursting at a free surface in a closed domain. Suppose that the fluid outside the bubble is incompressible, non-viscous and irrotational and the velocity potential satisfies the Laplace equation. Boundary integral method is used to solve the Laplace equation for the velocity potential. The bubble content is described by an adiabatic law. The whole process of the bubble motion and subsequently the water wave propagation will be simulated in this paper. Particular attention will be focused on the phenomenon of water wave propagation in a closed domain.

About the equilibrium speed of sound in a liquid with gas-vapor bubbles

The general expression of an equilibrium velocity of a sound in vapor-gas-liquid mixtures is presented and influence of concentration of vapor and a volume content of bubbles on the received expression is analyzed. In special cases, for gas-liquid and vapor-liquid mixtures expressions of an equilibrium velocity are presented and the satisfactory consent of the received expressions with known experimental data is discovered.

Limited role for thermal erosion by turbulent lava in proximal Athabasca Valles, Mars.

The Athabasca Valles flood lava is among the most recent (<50 Ma) and best preserved effusive lava flows on Mars and was probably emplaced turbulently. The Williams et al. [2005] model of thermal erosion by lava has been applied to what we term "proximal Athabasca," the 75 km long upstream portion of Athabasca Valles. For emplacement volumes of 5000 and 7500 km3 and average flow thicknesses of 20 and 30 m, the duration of the eruption varies between ~11 and ~37 days. The erosion of the lava flow substrate is investigated for three eruption temperatures (1270°C, 1260°C, and 1250°C), and volatile contents equivalent to 0-65 vol% bubbles. The largest erosion depths of ~3.8-7.5 m are at the lava source, for 20 m thick and bubble-free flows that erupted at their liquidus temperature (1270°C). A substrate containing 25 vol% ice leads to maximum erosion. A lava temperature 20°C below liquidus reduces erosion depths by a factor of ~2.2. If flow viscosity increases with increasing bubble content in the lava, the presence of 30-50 vol % bubbles leads to erosion depths lower than those relative to bubble-free lava by a factor of ~2.4. The presence of 25 vol % ice in the substrate increases erosion depths by a factor of 1.3. Nevertheless, modeled erosion depths, consistent with the emplacement volume and flow duration constraints, are far less than the depth of the channel (~35-100 m). We conclude that thermal erosion does not appear to have had a major role in excavating Athabasca Valles.

Multi-analytical approach for monitoring the freezing process of a milkshake based product

On or off-line controls of the freezing process, used to ensure the desired final quality of frozen dairy desserts, is an important task, especially for manufacturers who consider the standard of production as a primary goal. One of the products of interest in this context is the milkshake, a drink that contains ice crystals and a precise content of air. Herein, we used three different techniques, based on as many prototypes, to monitor and control the freezing process of a milkshake based product over a period of 1–29h: an optical technique based on a digital microscope and image analysis, a rotational rheometer and a capacitive device. The optical technique characterized crystal growth and air content during freezing, and can be regarded as a reference method. The dimension of ice crystals and content of air bubbles showed a non-linear increase during preparation time. Correlations were high, with coefficients of determination up to 0.991. Parameters measured by other techniques, such as a rotational rheometer and a capacitive device, also showed good, logarithmic correlations with freezing time, with R2 values up to 0.964. Correlations between the main freezing parameters and data obtained with the rotational and capacitive techniques appeared good (R2 up to 0.983). Thus, these latter techniques might conceivably replace more complicated and expensive optical methods used to monitor the freezing process, especially when processing a product characterized by a constant composition.

Distributions of crystals and gas bubbles in reservoir ice during growth period

In order to understand the dominant factors of the physical properties of ice in ice thermodynamics and mechanics, in-situ observations of ice growth and decay processes were carried out. Two samplings were conducted in the fast and steady ice growth stages. Ice pieces were used to observe ice crystals and gas bubbles in ice, and to measure the ice density. Vertical profiles of the type and size of ice crystals, shape and size of gas bubbles, and gas bubble content, as well as the ice density, were obtained. The results show that the upper layer of the ice pieces is granular ice and the lower layer is columnar ice; the average crystal size increases with the ice depth and remains steady in the fast and steady ice growth stages; the shape of gas bubbles in the upper layer of ice pieces is spherical with higher total content, and the shape in the middle and lower layers is cylinder with lower total content; the gas bubble size and content vary with the ice growth stage; and the ice density decreases with the increase of the gas bubble content.

Development of low weight self-levelling mortars

This work shows the development of self levelling mortars, using micro bubbles based on aluminium silicate with a density of 0.25 g/cm3. Mortars formulations are composed by 8 different components in order to achieve properties balance between fresh and solid state. The mean objective is development light weight mortars with high fluidity and compression strength using micro bubbles and some additives. Formulations were designed employing Taguchi DOE of 8 variables and 3 states. Result analysis according to Taguchi method lets indentify the preponderant effect of each variable on the cited properties. Several formulations reached fluidity higher than 250%, with compression strength around 100 kg/cm2 and a low volumetric weigh. Obtained volumetric weights are 20% less than commercial self levelling mortars weight. Finally some relations are presented such: as relation water/cement with fluidity, and micro bubble content versus mortars volumetric weight, and finally compression strength versus the volumetric weight of mortars.

Constitutive Equation of Bubbly Oil Considering Shear Rate and Temperature

So far, the studies of the constitutive equation of bubbly oil have been limited to extremely low shear rate range, and the influence of the temperature has not been considered as well. The bubbly oil preparation device is set up, and the analytical technique based on image processing to characterize bubble content is proposed. The rheological performance of bubbly oil is then tested with Physica MCR 101 rotating rheological instrument within a wider range of shear rate under different temperature and bubble content. The influences of shear rate, temperature and bubble content on the rheological performance of bubbly oil are studied. A novel viscosity model and constitutive equation of CD15W/40 are developed, which can be applied to the situations with various shear rates and temperatures. The results show that at the same shear rate, the features of shear thinning of the bubbly oil are weakened as the temperature rises, while they are strengthened with the bubble content increasing. The influence of bubble content on the viscosity of bubbly oil is dependent on the shear rate. As the bubble content increases, the viscosity increases under lower shear rate, while the viscosity decreases under higher shear rate.

Study of Bubbles Elimination in Silica Glass Produced by Flame Fusion from Brazilian Natural Quartz Powder

Silica glass is a fundamental material for the high technology industry due to its physical properties. This material is widely used in the semiconductor, chemical and optical industry. For applications in the optical industry and special lamps, it is necessary that the silica has a reduced content of bubbles and high optical transmittance in the wavelength regions of visible and medium ultraviolet (200 nm – 300 nm). Silica glass samples were produced by the flame fusion Verneuil Method of Brazilian commercial natural quartz powder and imported high purity commercial powder. An acid leaching procedure of the national quartz powder was introduced before the fusion in order to decrease bubbles concentration. The results were compared with the silica glass produced with imported quartz powder and a commercial silica glass used for the fabrication of special lamps, showing an excellent feasibility of application of Brazilian natural quartz to produce high value added silica glass.

Preparation of high open porosity ceramic foams via direct foaming molded and dried at room temperature

Abstract Herein an alternative approach was considered for addressing one difficulty of ceramic foams that the foam slurry with a high content of bubbles which were obtained via direct foaming, cannot maintain well for a long time at room temperature. It is fascinating that the foam slurry mentioned above could stably mold and dry at room temperature, based on an animal protein as foaming agent, kaolin, talc powder and alumina as raw materials, alpha-tricalcium phosphate prepared via co-precipitation as curing agent, and hydrophobic activated carbon powders as stabilizing agent. Effects of the calcination temperatures, the contents of alpha-tricalcium phosphate and activated carbon powder on microstructures, crystal phases, compressive strength and open porosities of ceramic foams were studied systematically. The results indicated that ceramic foams with a high open porosity and uniform pore distribution and sizes sought for application in catalysts supports, could be produced by adjusting these parameters.

Plant-mediated transport and isotopic composition of methane from shallow tropical wetlands

The methane (CH4) content of gas bubbles in sediments and CH4 emission from plants in the Pantanal wetland of Brazil was examined across a depth gradient to ascertain the relative importance of plant-mediated CH4 emission versus ebullition. Sediment bubbles contained >50% CH4 at sites with water depths >1 m but often contained <50% CH4 in shallower waters. Previous work has shown that bubble % CH4 is related to ebullition rates, and therefore these patterns are suggestive of greater CH4 emission by ebullition from deeper waters compared to waters <1 m in depth. Stable isotope ratios of carbon and hydrogen in the CH4 showed evidence for significant CH4 oxidation but no apparent relation with water depth. Shallower waters typically contain rooted emergent plants with erect, vertical stems or petioles, whereas in waters deeper than ~1 m, emergent aquatic plants are limited to rooted forms with long stems that float at the water surface. Rooted emergent plants typical of deeper waters had low rates of CH4 emission (0.0–0.2 mg d−1 CH4 for individual plants) compared to species typical of inundation depths <1 m (1.6–7.5 mg d−1 CH4). These observations suggest that tropical savanna floodplains like the Pantanal with inundation depths >1 m have low rates of CH4 emission via rooted emergent and floating-leaf plants, in contrast to results from shallower rice fields and temperate wetlands in which plant-mediated transport dominates CH4 emission from vegetated waters.

A discussion of possible measurement techniques for muddy sediments and of the related modeling challenges

Present paper draws on recent work of the late William Carey at Dodge Pond, CT, and on related modeling efforts at RPI. Carey affirmed that muddly sediments can have a substantial air bubble content. The water, solid particles (clay), and bubbles lead to a low sound speed that for low frequencies is explained by a modification of the Mallock-Wood formula. Independent measurements of mass density and sound speed should enable estimates of the fractional composition. The attenuation of sound in muddy sediments without bubbles is small, much smaller than of sandy sediments, and this is explained in terms of the card house model because of the very small size of the clay particles. The larger bubbles are randomly dispersed and have flattened shapes (also explained by the card-house model), and lead to scattering and reflection phenomena. Speculations are made as to whether inversion techniques can be devised to determine bubble shapes and size distributions. The small shear modulus of muddy segments has been tentatively explained in terms of electrostatic effects inherent to the card-house model, and this can possibly be measured by interface waves. Paper also suggests that penetrometer measurements, guided by theoretical modeling, may lead to useful inferences.