Soap Bubbles Research Articles

Charged Cavitation Multibubbles Dynamics Model: Growth Process

The nonlinear dynamics of charged cavitation bubbles are investigated theoretically and analytically in this study through the Rayleigh–Plesset model in dielectric liquids. The physical and mathematical situations consist of two models: the first one is noninteracting charged cavitation bubbles (like single cavitation bubble) and the second one is interacting charged cavitation bubbles. The proposed models are formulated and solved analytically based on the Plesset–Zwick technique. The study examines the behaviour of charged cavitation bubble growth processes under the influence of the polytropic exponent, the number of bubbles N, and the distance between the bubbles. From our analysis, it is observed that the radius of charged cavitation bubbles increases with increases in the distance between the bubbles, dimensionless phase transition criteria, and thermal diffusivity, and is inversely proportional to the polytropic exponent and the number of bubbles N. Additionally, it is evident that the growth process of charged cavitation bubbles is enhanced significantly when the number of bubbles is reduced. The electric charges and polytropic exponent weakens the growth process of charged bubbles in dielectric liquids. The obtained results are compared with experimental and theoretical previous works to validate the given solutions of the presented models of noninteraction and interparticle interaction of charged cavitation bubbles.

Measurement of Three‐Dimensional Bubble distributionVia Single‐Directional Capture Using a Light Field Camera

In water electrolysis, which converts electricity into hydrogen, the distribution of bubbles affects ion transport in the electrolyte. Therefore, measuring the three‐dimensional distribution of bubbles in the electrolysis cell can be effective in improving efficiency. However, the electrolysis cell contains electrodes and membranes, making it difficult to use conventional stereo photography to measure the three‐dimensional bubble distribution. Therefore, in this study, we investigated the measurement of the three‐dimensional distribution of bubbles in liquids using a light field camera that enables three‐dimensional imaging from one direction by using a microlens array. The study was conducted by performing imaging experiments of bubbles ejected from an axisymmetric nozzle using a light field camera and determining whether the measurement of the three‐dimensional distribution of bubbles was possible. As a result, we found that the axisymmetric bubble distribution can be measured in three dimensions and that a light field camera can be used for this measurement. © 2024 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC.

Maximum entropy model of chaotic explosion and implosion of a large gas bubble in liquid

A mathematical model for the chaotic explosion of a large gas bubble in a liquid is presented in which there is a maximum increase in entropy. It is shown that this requires that the acoustic radiation during the chaos must be minimal and that the spherical surface at the end of the chaos must be stable. Also, a model including the acoustic radiation is developed for the spherical phases of the explosion and implosion of the bubble during which there is no change in entropy. The (final) chaotic phase of the implosion is also modeled so that there is a maximum increase in entropy. There might be additional periods of the bubble during which the bubble explodes and implodes in a similar fashion as the first period. The calculations using this model are shown to agree reasonably well with the data. In particular, these calculations determined that the ratio of the duration of the second period of the bubble to the first period imply that the energy lost in the first period during its implosion is about 2/3 of the energy of the first period. Also, these calculations determine that only about 30% of the total energy is radiated and the rest is absorbed by the water for a total of about 2/3 of the total energy. This also agrees with the data. Furthermore, the data appear to scale with initial total energy as in the calculations using this chaos model.

Modeling of vapor bubble dynamics considering the metastable fluid state

This study investigates the dynamic modeling of a spherical vapor bubble in an infinite liquid. Initially, the liquid is in a state of saturation, but then, there is a change in ambient pressure. Unlike previous studies that assumed vapor saturation, our model fully considers the metastable fluid state of subcooled vapor and superheated liquid. The theoretical model is based on the state equation of vapor and the kinetic theory of gases, allowing the visualization of the effects of superheating and subcooling on the bubble pressure and the phase transition rate. The accuracy of the numerical solutions for the bubble collapse and growth is confirmed by experimental results using water as the working fluid. Two approaches of heat transfer simplification are validated in the numerical solution, and an adhesion coefficient within the range of 0.1–1 is recommended for the calculation. Additionally, this study provides insights into how the metastable fluid state affects the bubble pressure and phase transition, especially in the early stages of bubble collapse. Furthermore, the conservation of vapor mass inside the bubble is also demonstrated.

Characteristics of velocity, bubble's radius, and pressure in liquid and gas bubble mixture

The study focuses on the formation of gas bubbles, a crucial phenomenon that significantly impacts the hydrodynamics in liquid–gas reactors. This phenomenon has been observed in industrial engineering, leading to the development of model equations that describe the velocity of a liquid–gas mixture, pressure, and deviation in the gas bubble's initial radius. Kudryashov–Sinelshchikov (KS) established coupled equations (CEs) to describe the dynamics of the liquid–gas mixture. Here, the study aims to investigate the behavior of velocity, deviation in the bubble radius, and pressures by deriving exact solutions of the KSCEs and representing them graphically. The findings show that the velocity can take negative or positive values, representing interfacial velocity or superficial velocity for both liquid and gas, respectively. The pressure may also be negative or positive, corresponding to the shrinking or stretchering of the liquid surface, respectively. The dynamics of the velocity and the deviation in the bubble radius exhibit similar qualitative behavior, while the pressure shows a variant behavior. The dominant parameters are found to be the gas bubble's initial radius and the polytropic exponent. The stability of the steady-state solution is also analyzed. This study contributes to the existing literature by examining the CEs, which have not been studied until now.

On the scalability of helium-filled soap bubbles for volumetric PIV

The scalability of experiments using PIV relies upon several parameters, namely illumination power, camera sensor and primarily the tracers light scattering capability. Given their larger cross section, helium-filled soap bubbles (HFSB) allow measurements in air flows over a significantly large domain compared to traditional oil or fog droplets. Controlling their diameter translates into scalability of the experiment. This work presents a technique to extend the control of HFSB diameter by geometrical variations of the generator. The latter expands the more limited range allowed by varying the relative helium-air mass flow rates. A theoretical model predicts the bubble size and production rate, which is verified experimentally by high-speed shadow visualization. The overall range of HFSB produced in a stable (bubbling) regime varies from 0.16 to 2.7 mm. Imaging by light scattering of such tracers is also investigated, in view of controversies in the literature on whether diffraction or geometrical imaging dominate the imaging regime. The light scattered by scaled HFSB tracers is imaged with a high-speed camera orthogonal to the illumination. Both the total energy collected on the sensor for a single tracer, as well as its peak intensity, are found to preserve scaling with the square of the diameter at object magnification of 10–1 or below, typical of PIV experiments. For large-scale volumetric applications, it is shown that varying the bubble diameter allows increasing both the measurement domain as well as the working distance of the imagers at 10 m and beyond. A scaling rule is proposed for the latter.Graphical abstract

Self-assembled soft alloy with Frank-Kasper phases beyond metals.

Soft building blocks, such as micelles, cells or soap bubbles, tend to adopt near-spherical geometry when densely packed together. As a result, their packing structures do not extend beyond those discovered in metallic glasses, quasicrystals and crystals. Here we report the emergence of two Frank-Kasper phases from the self-assembly of five-fold symmetric molecular pentagons. The μ phase, an important intermediate in superalloys, is indexed in soft matter, whereas the ϕ phase exhibits a structure distinct from known Frank-Kasper phases in metallic systems. We find a broad size and shape distribution of self-assembled mesoatoms formed by molecular pentagons while approaching equilibrium that contribute to the unique packing structures. This work provides insight into the manipulation of soft building blocks that deviate from the typical spherical geometry and opens avenues for the fabrication of 'soft alloy' structures that were previously unattainable in metal alloys.

The Flash Crash: The Impact of High-Frequency Trading on the Stability of Financial Market

The growing prevalence of High-Frequency Trading (HFT) in financial markets has sparked intense debate over its impact on market stability. This paper aims to research the adverse effects that come along with HFT's enhancement of liquidity and price discovery efficiency. It contrasts the hardware infrastructure and execution speeds of high-frequency automated trading against manual trading and analyzes how the liquidity bubbles provided by HFT contribute to market volatility. This paper then concludes with three main points. First, HFT can pose a threat to market stability. Second, specific HFT strategies may mislead other market participants and lead to price distortions. Lastly, HFT may exacerbate market participation inequality, posing a market fairness challenge. Based on these findings, this paper recommends that regulatory authorities and policymakers pay closer attention to the potential risks of HFT and implement measures to maintain market stability and fairness.

An evaluation of predictive correlations for the terminal rising velocity of a single bubble in quiescent clean liquid

Evaluation work was carried out on widely used correlations for predicting the terminal velocities of single bubbles rising in quiescent liquids against a database with 758 data points. The data were collected from the experiments of air bubbles rising in pure water with diameters covering 0.02–66.97 mm. The correlations are firstly categorized into three groups according to their application ranges: group 1 for spherical and ellipsoidal bubbles with rectilinear paths, group 2 for ellipsoidal bubbles with unstable paths and spherical-cap bubbles and group 3 for bubbles of all sizes. Evaluation results show that among group 1 correlations, the Moore (1965) correlation demonstrates the best MAE of 2.9% within its application range (Re ¿ 50). The Chen et al. correlation and Rastello et al. correlation, with the broadest application range in group 1, yield good overall MAEs of 7.0% and 5.0%, respectively. The Lehrer correlation gives the smallest MAE of 4.3% in group 2. In group 3, the Dijkhuizen et al. correlation and Baz-Rodríguez et al. correlation achieve the highest accuracy against all the experimental data, with global MAEs of 7.7% and 8.7%, respectively. Although present prediction methods have achieved good agreement with the experimental results, predicting the terminal velocity of ellipsoidal bubbles with unstable paths is the most intractable and lacks satisfactory methods, and it still remains challenging to develop a unified correlation.

Cellular instabilities of outwardly propagating spherical hydrogen-oxygen flames using a soap bubble method

Explosion hazards associated with hydrogen-oxygen mixtures remain a significant challenge for the energy industry, despite hydrogen garnering attention as a carbon emissions-free alternative energy source. While several studies have been conducted on hydrogen-air explosions, research on hydrogen-oxygen explosions has been limited. In the current study, we employed a spherical soap bubble method to experimentally investigate the flame propagation behavior of an unconfined hydrogen-oxygen explosion. The experimental values of the laminar burning velocity were in agreement with its calculated values and were notably higher than those observed hydrogen-air mixtures. In the case of hydrogen-oxygen mixtures, a spherical expanding flame is accelerated due to the presence of Darrieus-Landau and diffusive-thermal instabilities. Furthermore, we compared the correlation between the critical Pѐclet number and the critical Karlovitz number with the Markstein number for hydrogen-oxygen mixtures to results obtained with propane-oxygen and methane-oxygen mixtures.

Stability and rheological properties of firefighting foams with sodium carboxymethyl cellulose and hydrocarbon/silicone surfactants

Firefighting foam stability is a critical aspect in determining fire extinguishing efficiency. The stability and rheological properties of environmental firefighting foams are investigated in this work. The results show that increasing NaCMC polymer concentration decreases the equilibrium surface tension of CTAB/501W surfactants, while enhancing the viscosity and conductivity. And the yield strain and yield stress of the foam improve. However, when the NaCMC concentration is enhanced to 0.8 wt.%, the NaCMC concentration has less effect on the change in rheological characteristics. Slight NaCMC concentration addition enhances the foaming ability of CTAB/501W surfactant solutions, but further addition of NaCMC concentration decreases its foaming ability. Increasing NaCMC cocentration reduces the height decay of the foam produced by CTAB/501W surfactant solutions, retarding the bubble coarsening and liquid drainage process, and leading to foam stability enahncement, where the stability turning point occurs when NaCMC concentration is 0.5 wt.%. This is mainly attributed to the interaction between NaCMC polymer and CTAB molecule, and the increased viscosity.

3D simulation of pulsatile bubbly flow resembling decompression sickness conditions inside a realistic human artery

I-VED (In-Vivo Embolic Detector) is a novel diagnostic tool for non-invasive, real-time detection of bubbles in humans. Bubbles are precursors of decompression sickness (DCS), which can be encountered in astronauts, scuba divers, etc. I-VED exploits an EU patented electrical impedance spectroscopy technology, developed under the umbrella of a European Space Agency project. So far, I-VED has been calibrated and validated in vitro. In view of the forthcoming in-vivo trials, it needs to be configured for sensing bubbles in the bloodstream. For this, 3D computational fluid dynamics simulation is performed to investigate axial and radial variation of void fraction (α) and flow velocity (U) in a pulsatile bubbly flow inside a realistic human artery (diameter: 5–20 mm, implying vessel dilatation or contraction), where liquid velocity, bubble size, and void fraction resemble DCS conditions. Results show that U and α show a core-peaking profile despite the variation of artery diameter, while 3D sharp turns yield U and α non-uniformities in the angular direction that do not affect mean void fraction across the artery. Obtained knowledge allows deeper insight on the physics and spatial characteristics of bubbly flow in a real artery, which is useful in the design of measuring volume and tuning of I-VED.

Highly efficient pool boiling heat transfer on surfaces with zoned rose-petal-inspired hierarchical structures

Efficient boiling heat transfer depends on the rapid formation and detachment of vapor bubbles on solid surfaces. However, this process is hindered by the contradictory requirements of bubble nucleation and departure. Herein, a novel surface with zoned rose-petal-inspired hierarchical structures is prepared on copper by laser-based methods to promote bubble nucleation and detachment simultaneously. The surface features parahydrophobic rose zones surrounded by superwetting pump zones. The rose-petal-inspired hierarchical structures on the rose zones greatly enhance the bubble nucleation, resulting in very high heat transfer coefficients (HTC). The pump zones with hierarchical mini-nanostructures facilitate the formation of distinct pathways for liquid and vapor flows, enabling efficient liquid rewetting and bubble departure at high heat fluxes. The synergistic effects of the rose and pump zones enhance both bubble nucleation and departure, leading to superior boiling performance. The critical heat flux (CHF) and the HTC achieved at the CHF (HTC@CHF) increase by 100% and 360%, respectively, compared to a smooth surface. Our results provide new avenues for the development of metal-based highly efficient boiling surfaces, which may enhance the efficiency of energy utilization and heat dissipation of various thermal management devices.

Smectic and Soap Bubble Optofluidic Lasers

Soap bubbles are simple, yet very unique and marvelous objects. They exhibit a number of interesting properties such as beautiful interference colors and the formation of minimal surfaces. Various optical phenomena have been studied in soap films and bubbles, but so far they have not been employed as optical cavities. Here we demonstrate that dye doped soap or smectic liquid crystal bubbles can support whispering gallery mode lasing, which is observed in the spectrum as hundreds of regularly spaced peaks, resembling a frequency comb. The lasing enabled the measurement of size changes as small as 10 nm in a millimeter-sized, ∼100−nm-thick bubble. Bubble lasers were used as extremely sensitive electric field sensors with a smallest measurable electric field of 110 Vm−1 Hz−1/2. They also enable the measurement of pressures up to a 100 bar with a resolution of 1.5 Pa, resulting in a dynamic range of almost 107. By connecting the bubble to a reservoir of air, almost arbitrarily low pressure changes can be measured while maintaining an outstanding dynamic range. The demonstrated soap bubble lasers are a very unique type of microcavities which are one of the best electric field and pressure microsensors to date and could in the future also be employed to study thin films and cavity optomechanics. Published by the American Physical Society 2024

Liquid inertia versus bubble cloud buoyancy in circular plunging jet experiments

When a liquid jet plunges into a pool, it can generate a bubble-laden jet flow underneath the surface. This common and simple phenomenon is investigated experimentally for circular jets to illustrate and quantify the role played by the net gas/liquid void fraction on the maximum bubble penetration depth. It is first shown that an increase in either the impact diameter or the jet fall height to diameter ratio at constant impact momentum leads to a reduction in the bubble cloud size. By measuring systematically the local void fraction using optical probes in the biphasic jet, it is then demonstrated that this effect is a direct consequence of the increase in air content within the cloud. A simple momentum balance model, including only inertia and the buoyancy force, is shown to predict the bubble cloud depth without any fitting parameters. Finally, a Froude number based on the bubble terminal velocity, the cloud depth and also the net void fraction is introduced to propose a simple criterion for the threshold between the inertia-dominated and buoyancy-dominated regimes.

Design and manufacture a syringe pump for intelligent injection of specific doses of contrast medicine in medical imaging applications

The construction of an Arduino Uno based syringe pump with the ability to measure the patient's body temperature during injection and detect the contrast material bubble has not been done so far. A syringe pump is a device that controls the volume and flow of milliliters to microliters for a certain period of time with very high precision, which gradually pushes the injection piston. This use of syringe pump for drug administration has been done for years. The working principle of this system consists of installing two steel rods to push the syringe piston at a set speed, which works through a coupling system. The advancement of technology has made it possible to use a motor as the driving force of the syringe filled with liquid released through the needle, and the electronic system in this tool is used as a controller. The design using a stepper motor based on Arduino Uno is chosen to adjust the flow rate; the research includes two stages of software and hardware construction. The hardware is implemented with the components needed to build a syringe pump with an Arduino Uno as the brain of the system and a stepper motor as a piston pusher.The flow rate in the syringe pump can be adjusted with the keyboard and displayed on the screen. It is also possible to see the patient's body temperature on the screen, and to detect bubbles in the contrast liquid during injection, we also put a sensor in this device that alerts the operator.

Imaging aspects of maxillomandibular bone alterations in patients with multiple myeloma treated with bisphosphonates: A systematic review.

Multiple myeloma (MM) is a rare cancer that is typically managed with bisphosphonates to slow bone resorption and prevent skeletal complications. This study aimed to identify imaging patterns in MM patients receiving bisphosphonate therapy. This systematic review included studies investigating maxillomandibular bone alterations based on imaging examinations in MM patients treated with bisphosphonates. The selected studies were qualitatively assessed using the Critical Appraisal Tools from SUMARI. Six studies, involving 669 MM patients, were included, with 447 receiving bisphosphonate treatment. The majority were treated with pamidronate, zoledronate, or a combination of both. Seventy patients developed medication-related osteonecrosis of the jaw (MRONJ), predominantly in the mandible, characterized by the presence of bony sequestrum, bone sclerosis, increased periodontal ligament space, osteolytic lesions, and osteomyelitis as observed in imaging analyses. For non-MRONJ lesions, the mandible also exhibited the highest frequency of asymptomatic bone alterations. These ranged from "punched-out" osteolytic lesions or "soap bubble" lesions to solitary bone lesions, areas of bone sclerosis, abnormalities of the hard palate, osteoporosis, non-healed alveoli, and cortical bone rupture. MM patients treated with bisphosphonates display radiographic patterns of maxillomandibular bone lesions. These patterns aid in diagnosis and facilitate early and targeted treatment, thereby contributing to improved morbidity outcomes for these patients.

19Multidisciplinary analysis of two pictures by D. Dobrovich – a preliminary report

In this work, we are presenting a preliminary study of the pigments used in two paintings by Dimitar Dobrovich: "Children playing with soap bubbles," oil on canvas, and "Roma. Girl with a Jar", oil on canvas. They were analyzed non-destructively by means of X-ray fluorescence (p-XRF) and Raman spectrometry. Chemical analysis of the used pigments and the obtained analytical results show a very rich palette, including cinnabar, ochre, lead white, lead yellow, minium, realgar/orpiment, gold, etc. The interest in the technical-technological features of these paintings aims to determine the specific issues for conservation and restoration purposes. This particular task is part of a larger study of more than 70 paintings from the private collection of Mr. Miroslav Dachev, subject of multidisciplinary analyses for autentification.

Spatiotemporal mapping of nanotopography and thickness transitions of ultrathin foam films.

Freshly formed soap films, soap bubbles, or foam films display iridescent colors due to thin film interference that changes as squeeze flow drives drainage and a progressive decrease in film thickness. Ultrathin (thickness <100 nm) freestanding films of soft matter containing micelles, particles, polyelectrolyte-surfactant complexes, or other supramolecular structures or liquid crystalline phases display drainage via stratification. A fascinating array of thickness variations and transitions, including stepwise thinning and coexistence of thick-thin flat regions, arise in micellar foam films that undergo drainage via stratification. In this tutorial, we describe the IDIOM (interferometry digital imaging optical microscopy) protocols that combine the conventional interferometry principle with digital filtration and image analysis to obtain nanometer accuracy for thickness determination while having high spatial and temporal resolution. We provide fully executable image analysis codes and algorithms for the analysis of nanotopography and summarize some of the unique insights obtained for stratified micellar foam films.

Study of hydrate nucleation and growth aided by micro-nanobubbles: Probing the hydrate memory effect

Gas hydrates have been considered promising in gas storage, gas separation, and water desalination. The hydrates' technical application is affected by the long kinetics time. Of interest is gas hydrates show strong facilitation in dissociated water containing a high concentration of micro-nanobubbles. Here, it was discovered that the nano-particles present in the dissociated water were identified as nano-bubbles, characterized by nanoparticle track analyzer and infrared spectrum. The presence of bubbles increased the nucleation probability, likely attributed to the provision of nucleation sites. Results indicated that the ability of facilitation was related to the nanobubble types: the bubble solution with the same guest molecules exhibited similar facilitation to dissociated water; specifically, the average induction time was shortened by 27.48 %, the nucleation probability was increased by 50 % compared to deionized water. Moreover, the time hydrate filled the field of view with high bubble concentration was reduced by 60 % compared with low bubble concentration. The facilitation effect mechanism could be related to the presence of gas-dense regions inside the bubbles, based on the Raman results. This finding may offer valuable insights for the application of hydrate-based energy storage technology and shed light on the potential role of bubbles in causing memory effects.