Gas Fraction Research Articles

Astronomy's climate emissions: Global travel to scientific meetings in 2019.

Travel to academic conferences-where international flights are the norm-is responsible for a sizeable fraction of the greenhouse gas (GHG) emissions associated with academic work. In order to provide a benchmark for comparison with other fields, as well as for future reduction strategies and assessments, we estimate the CO2-equivalent emissions for conference travel in the field of astronomy for the prepandemic year 2019. The GHG emission of the international astronomical community's 362 conferences and schools in 2019 amounted to 42,500 tCO2e, assuming a radiative-forcing index factor of 1.95 for air travel. This equates to an average of 1.0 ± 0.6 tCO2e per participant per meeting. The total travel distance adds up to roughly 1.5 Astronomical Units, that is, 1.5 times the distance between the Earth and the Sun. We present scenarios for the reduction of this value, for instance with virtual conferencing or hub models, while still prioritizing the benefits conferences bring to the scientific community.

Gas and Star Formation in Satellites of Milky Way Analogs

We have imaged the entirety of eight (plus one partial) Milky Way (MW)–like satellite systems, a total of 42 (45) satellites, from the Satellites Around Galactic Analogs II catalog in both Hα and H i with the Canada–France–Hawaii Telescope and the Jansky Very Large Array. In these eight systems we have identified four cases where a satellite appears to be currently undergoing ram pressure stripping (RPS) as its H i gas collides with the circumgalactic medium (CGM) of its host. We also see a clear suppression of gas fraction (M HI/M *) with decreasing (projected) satellite–host separation—to our knowledge, the first time this has been observed in a sample of MW-like systems. Comparisons to the Auriga, A Project Of Simulating The Local Environment, and TNG50 cosmological zoom-in simulations show consistent global behavior, but they systematically underpredict gas fractions across all satellites by roughly 0.5 dex. Using a simplistic RPS model, we estimate the average peak CGM density that satellites in these systems have encountered to be logρcgm/gcm−3≈−27.3 . Furthermore, we see tentative evidence that these satellites are following a specific star formation rate to gas fraction relation that is distinct from field galaxies. Finally, we detect one new gas-rich satellite in the UGC 903 system with an optical size and surface brightness meeting the standard criteria to be considered an ultra-diffuse galaxy.

Gas-liquid-soild triphasic continuous flow microreactor for improving homogeneous distribution of solid composites in heterogeneous photocatalytic degradation progress

The homogeneous distribution of solid composites in continuous flow photocatalytic progress is difficult due to the settle and clog in capillary. To overcome this challenge, a gas–liquid-soild triphasic continuous flow photoreactor was designed and used for heterogeneous photocatalytic degradation of antibiotics wastewater. In this work, take Bi2WO6 as photocatalyst, photocatalytic degradation of ofloxacin wastewater was studied systematically under different operational parameters and flow characteristics. The photocatalytic degradation performance of flow photoreactor was superior to batch counterpart, especially in later stage of reaction. The apparent reaction rate constants (k) of flow photoreactor was about 1.6 times that of batch counterpart. The gas–liquid mass transfer coefficient of flow photoreactor was more than 25 times that of batch photoreactor. Moreover, the influence mechanism of gas fraction, flow rate and tube diameter on photocatalytic degradation performance was investigated under various continuous flow conditions. Higher gas fraction, faster flow rate and smaller tube diameter were beneficial to improve photocatalytic degradation performance due to the enhancement of irradiation transmission and intensification of mass transfer. Therefore, the results of this work provided a guideline for the application of gas–liquid-soild triphasic continuous flow photocatalytic degradation technology in the future.

Studying the Effects of Dissolved Noble Gases and High Hydrostatic Pressure on the Spherical DOPC Bilayer Using Molecular Dynamic Simulations.

Fine-grained molecular dynamics simulations have been conducted to depict lipid objects enclosed in water and interacting with a series of noble gases dissolved in the medium. The simple point-charge (SPC) water system, featuring a boundary composed of 1,2-Dioleoyl-sn-glycero-3-phosphocholine (DOPC) molecules, maintained stability throughout the simulation under standard conditions. This allowed for the accurate modeling of the effects of hydrostatic pressure at an ambient pressure of 25 bar. The chosen pressure references the 240 m depth of seawater: the horizon frequently used by commercial divers, who comprise the primary patient population of the neurological complication of inert gas narcosis and the consequences of high-pressure neurological syndrome. To quantify and validate the neurological effects of noble gases and discriminate them from high hydrostatic pressure, we reduced the dissolved gas molar concentration to 1.5%, three times smaller than what we previously tested for the planar bilayer (3.5%). The nucleation and growth of xenon, argon and neon nanobubbles proved consistent with the data from the planar bilayer simulations. On the other hand, hyperbaric helium induces only a residual distorting effect on the liposome, with no significant condensed gas fraction observed within the hydrophobic core. The bubbles were distributed over a large volume-both in the bulk solvent and in the lipid phase-thereby causing substantial membrane distortion. This finding serves as evidence of the validity of the multisite distortion hypothesis for the neurological effect of inert gases at high pressure.

Pyrolysis of Specific Non-Recyclable Waste Materials: Energy Recovery and Detailed Product Characteristics.

This study explores the pyrolysis process applied to various non-utilized waste materials, specifically focusing on separated plastics from municipal waste, wood waste (including pallets and window frames), paper rejects, and automotive carpets. Different combinations of these waste materials were subjected to pyrolysis, a process involving high-temperature treatment (600 °C) in a nitrogen atmosphere. The resulting products, including biochar, gas, and liquid fractions, as well as the residual waste materials, underwent comprehensive analysis. The evaluation of pyrolysis products emphasizes their quality, energy content, and potential applications. Notably, the pyrolysis gas derived from the combination of separated municipal plastics and waste wood exhibited the highest calorific value at 49.45 MJ/m3. Additionally, Mixture 2, consisting of plastic and wood waste, demonstrated the highest calorific value for the pyrolysis condensate, reaching 30.62 MJ/kg. Moreover, Mixture 3, benefiting from biochar utilization as a sorbent, displayed the highest iodine value at 90.01 mg/g.

Mass yields of products and composition of syngas from pyrolysis of Brazilian plastic solid wastes: Combustion simulation and burner design to minimize COx and CxHy emissions

For the first time, the mass yields of products and the composition of synthesis gas (syngas) from pyrolysis of Brazilian plastic solid waste were evaluated for a reactor processing 20 g of plastic at 800 °C. Combustion of the syngas was simulated, evaluating the levels of COx and CxHy emissions, and a burner was designed to minimize emissions during combustion. The main findings highlighted the importance of performing thermogravimetric analyses of waste materials. Higher thermal degradation temperatures (530–900 °C) were obtained for all the plastics, compared to values reported in the literature (300–600 °C). Between 46.7 and 98.0 wt% of syngas was produced, with lower heating values ranging from 10390 to 45684 kJ kg−1, due to differences between the plastics in the fractions of inorganic and hydrocarbon gases produced. The maximum temperatures for syngas combustion, simulated using ANSYS software, were 2000 and 800 °C inside the burner and combustion chamber, respectively. In the burner, higher COx and CxHy levels were related to the syngas composition and incomplete chemical reactions in the flame zone. The CO and CxHy levels decreased towards the combustion chamber, where CO2 was less than 8 wt%, in compliance with the CONAMA 316/2002 regulation.

Comprehensive laboratory constraints on thermal desorption of interstellar ice analogues

Gas accretion and sublimation in various astrophysical conditions are crucial aspects of our understanding of the chemical evolution of the interstellar medium. To explain grain growth and destruction in warm media, ice mantle formation and sublimation in cold media, and gas line emission spectroscopy, astrochemical models must mimic the gas--solid abundance ratio. Ice-sublimation mechanisms determine the position of snow lines and the nature of gas emitted by and locked inside planetary bodies in star-forming regions. To interpret observations from the interplanetary and extragalactic interstellar mediums, gas phase abundances must be modelled correctly. We provide a collection of thermal desorption data for interstellar ice analogues, aiming to put constraints on the trapping efficiency of water ice, as well as data that can be used to evaluate astrochemical models. We conduct experiments on compact, amorphous H$_2$O films, involving pure ices as well as binary and ternary mixtures. By manipulating parameters in a controlled way, we generate a set of benchmarks to evaluate both the kinetics and thermodynamics in astrochemical models. We conducted temperature-programmed desorption experiments with increasing order of complexity of ice analogues of various chemical compositions and surface coverages using molecular beams in ultrahigh vacuum conditions (1 times 10$^ $ hPa) and low temperatures (10 K). We provide TPD curves of pure ices made of Ar, CO, CO$_2$, NH$_3$, CH$_3$OH, H$_2$O, and NH$_4^+$HCOO$^-$, their binary ice mixtures with compact amorphous H$_2$O, ternary mixtures of H$_2$O : CH$_3$OH : CO, and a water ice made in situ to investigate its trapping mechanisms. Each experiment includes the experimental parameters, ice desorption kinetics for pure species, and the desorption yield (gas--solid ratio) for ice mixtures. From the desorption yields, we find common trends in the trapping of molecules when their abundance is compared to water: compact amorphous water ices are capable of trapping up to 20<!PCT!> of volatiles (Ar, CO, and CO$_2$), sim 3<!PCT!> of CH$_3$OH, and sim 5<!PCT!> NH$_3$ in relation to the water content within the ice matrix; ammonium formate is not trapped in the water ice films, and compact amorphous water ice formed in situ has similar trapping capabilities to a compact amorphous water ice deposited using molecular beams. Deposited or formed in a very compact structure, amorphous water ice of less than 100 layers cannot trap a large fraction of other gases, including CO and CO$_2$. These desorption yields offer insights into the availability of species that can react and form interstellar complex organic molecules during the warm-up phase of ice mantles. Furthermore, in order to be reliable, gas-grain astrochemical models should be able to reproduce the desorption kinetics and desorption yield presented in our benchmark laboratory experiments.

Super-early JWST galaxies, outflows, and Lyα visibility in the Epoch of Reionization

The overabundance of super-early (redshift z > 10) luminous (MUV < −20) blue galaxies detected by JWST has been explained as being due to negligible dust attenuation in these systems. We show that this model correctly reproduces the UV luminosity function at z > 10 and the star formation rate (SFR) density evolution. The model also predicts, in agreement with data, that the cosmic specific SFR (sSFR) grows as sSFR ∝ (1 + z)3/2. At z ≃ 10, the cosmic sSFR crosses the critical value sSFR⋆ = 25 Gyr−1, and approximately 45% of the galaxies become super-Eddington, driving outflows reaching velocities of ≈830(ϵ⋆/fM)1/2 km s−1, where ϵ⋆ and fM are the star formation efficiency and fraction of the halo gas expelled in the outflow, respectively. This prediction is consistent with the outflow velocities measured in 12 super-Eddington galaxies of the JWST/JADES sample. Such outflows clear the dust, thus boosting the galaxy luminosity. They also dramatically enhance the visibility of the Lyα line from z > 10 galaxies by introducing a velocity offset. The observed Lyα properties in GN-z11 (z = 10.6) are simultaneously recovered by the outflow model if log NHI ≃ 20.1, implying that the outflow is largely ionized. We make analogous predictions for the Lyα visibility of other super-early galaxies, and we compare the model with Lyα surveys at z > 7, finding that essentially all super-Eddington (sub-Eddington) galaxies are (not) detected in Lyα. Finally, the sSFR positively correlates with the LyC escape fraction, as outflows carve ionized transparent channels through which LyC photons leak.

N2H+(1–0) as a tracer of dense gas in and between spiral arms

ABSTRACT Recent advances in identifying giant molecular filaments in Galactic surveys allow us to study the interstellar material and its dense, potentially star forming phase on scales comparable to resolved extragalactic clouds. Two large filaments detected in the 13CO/C18O(J = 3–2) Heterodyne Inner Milky Way Plane Survey (CHIMPS) survey, one in the Sagittarius-arm and one in an interarm region, were mapped with dense gas tracers inside a 0.06 square degrees area and with a spatial resolution of around 0.4 and 0.65 pc at the distance of the targets using the 30 m telescope of the Institut de Radioastronomie Millimétrique (IRAM) to investigate the environmental dependence of the dense gas fraction. The N2H+(1 − 0) transition, an excellent tracer of the dense gas, was detected in parsec-scale, elliptical clumps and with a filling factor of around 8.5 per cent in our maps. The N2H+-emitting areas appear to have higher dense gas fraction (e.g. the ratio of N2H+ and 13CO emission) in the interarm than in the arm which is opposite to the behaviour found by previous studies, using dust emission rather than N2H+ as a tracer of dense gas. However, the arm filament is brighter in 13CO and the infrared emission of dust, and the dense gas fraction determined as above is governed by the 13CO brightness. We caution that measurements regarding the distribution and fraction of dense gas on these scales may be influenced by many scale- and environment-dependent factors, as well as the chemistry and excitation of the particular tracers, then consider several scenarios that can reproduce the observed effect.

Simulation of Underground Coal-Gasification Process Using Aspen Plus

In order to study the underground coal-gasification process, Aspen Plus software was used to simulate the lignite underground gasification process, and a variety of unit operation modules were selected and combined with the kinetic equations of coal underground gasification. The model can reflect the complete gasification process of the coal underground gasifier well, and the simulation results are more in line with the experimental results of the lignite underground gasification model test. The changes in the temperature and pressure of oxygen, gasification water, spray water, and syngas in pipelines were studied, and the effects of pipe diameters on pipeline conveying performance were investigated as well. The effects of the oxygen/water ratio, processing capacity, and spray-water volume on the components of syngas and components in different reaction zones were studied. In addition, the change tendency of gasification products under different conditions was researched. The results indicate that: (1) The depth of injection and the formation pressure at that depth need to be taken into account to determine a reasonable injection pressure. (2) The liquid-water injection process should select a lower injection pressure. (3) Increasing the oxygen/water ratio favors H2 production and decreasing the oxygen/water ratio favors CH4 production. (4) The content of CO2 is the highest in the oxidation zone, the lowest in the reduction zone, and then increases a little in the methanation reaction zone for the transform reaction. The content of CO is the lowest in the oxidation zone and the highest in the reduction zone. In the methanation reaction zone, CO partially converts into H2 and CO2, and the content of CO is reduced. (5) The injection of spray water does not affect the components of the gas but will increase the water vapor content in the gas; thus, this changes the molar fraction of the wet gas.

Predicting the Scaling Relations between the Dark Matter Halo Mass and Observables from Generalised Profiles II: Intracluster Gas Emission

Abstract We investigate the connection between a cluster’s structural configuration and observable measures of its gas emission that can be obtained in X-ray and Sunyaev-Zeldovich (SZ) surveys. We present an analytic model for the intracluster gas density profile: parameterised by the dark matter halo’s inner logarithmic density slope, α, the concentration, c, the gas profile’s inner logarithmic density slope, ε, the dilution, d, and the gas fraction, η, normalised to cosmological content. We predict four probes of the gas emission: the emission-weighted, TX, and mean gas mass-weighted, Tmg, temperatures, and the spherically, Ysph, and cylindrically, Ycyl, integrated Compton parameters. Over a parameter space of clusters, we constrain the X-ray temperature scaling relations, M200 – TX and M500 – TX, within 57.3% and 41.6%, and M200 – Tmg and M500 – Tmg, within 25.7% and 7.0%, all respectively. When excising the cluster’s core, the M200 – TX and M500 – TX relations are further constrained, to within 31.3% and 17.1%, respectively. Similarly, we constrain the SZ scaling relations, M200 – Ysph and M500 – Ysph, within 31.1% and 17.7%, and M200 – Ycyl and M500 – Ycyl, within 25.2% and 22.0%, all respectively. The temperature observable Tmg places the strongest constraint on the halo mass, whilst TX is more sensitive to the parameter space. The SZ constraints are sensitive to the gas fraction, whilst insensitive to the form of the gas profile itself. In all cases, the halo mass is recovered with an uncertainty that suggests the cluster’s structural profiles only contribute a minor uncertainty in its scaling relations.

Hydrodynamic Study of a Hybrid Electro-Flotation Column

Bubble columns are used in the mining industry for mineral recovery but are also widely utilized in the chemical and petrochemical industry. The hydrodynamic characteristics of their performance is a field of interest with a number of points, which are nonetheless poorly understood, and a considerable amount of methods have aimed to shed light on the flow regimes that prevail in the columns. The study of the hydrodynamic part of a flotation process should consider characteristics such as air flow, volumetric gas fraction, flow field, and bubble size, along with the mechanical and design factors and pulp properties. The present work aims to elucidate the characteristics of the gas phase of a hybrid flotation system. For this purpose, a hybrid flotation column was designed and constructed and the bubbles size distributions at different radial positions in the flotation column were computed by analyzing high resolution digital images. A patented electrical impedance technique was employed to instantaneously measure the local volumetric gas fraction. Flow dispersion in the column was studied by residence time distributions using conductivity tracers. The experimental results are discussed to comprehend the variation in the gas fraction in the column. In particular, the study showed that the size of the bubbles changed from the center to the walls of the column, and this was observed both radically and vertically. Moreover, the size of the bubbles affected the volume fractions, and no coalescence of the bubbles was observed. Finally, the dispersion of the tracer in the working solution was distributed uniformly in the volume of the column, with a time difference for the four positions of the column.

Measurement of steam dryness using one-dimensional acoustic waves in pipelines

Heavy oil, extra-heavy oil and bitumen exceed 6 trillion barrels, roughly three times the world total Conventional oil and gas reserves. Thermal-chemical flooding (TCF) is an effective alternative to enhance heavy oil recovery after steam injection. In the steam injection and extraction process of oil, the accurate measurement of water steam dryness can provide a strong guarantee for the efficient exploitation of oil fields. The traditional steam dryness measurement device is affected by the steam flow state, and the error generated will affect the enthalpy calculation of the injected steam, which affects the judgment of energy efficiency of oil well injection in the field. Firstly, this paper proposes a mathematical model for calculating water steam dryness using mixed sound velocity and operating temperature, which is based on the mathematical relationship between water steam dryness and gaseous volume fraction, combined with Wood's formula and the density and sound velocity calculation formula for each region in the IAPWS-IF97 model to derive the monotonic correspondence function of sound velocity and dryness. Secondly, the one-dimensional acoustic wave model of the pipeline is applied to establish a set of sound velocity equations for the frequency-domain data of the array sensors, and the traversal iteration method is used to solve the mixed sound velocity of water steam. Finally, the dryness of steam injection under the operating condition of 270°C∼290°C at the wellhead was measured in the experimental area H33 in Xinfanguan of Liaohe Oilfield, and compared with the standard dryness value, the relative error of the experiment was -3.33% and the repeatability was 1.24%, the accuracy met the requirements of energy efficiency calculation, which verified the feasibility of the sound velocity method to measure the dryness of water steam. Therefore, it is of great engineering guiding significance to utilize sound velocity method to realize the measurement of dryness in the thick oil steam injection process.

Differences in the properties of disrupted and surviving satellites of Milky-Way-mass galaxies in relation to their host accretion histories

ABSTRACT From the chemodynamical properties of tidal debris in the Milky Way, it has been inferred that the dwarf satellites that have been disrupted had different chemical abundances from their present-day counterparts of similar mass that survive today, specifically, they had lower [Fe/H] and higher [Mg/Fe]. Here we use the Artemis simulations to study the relation between the chemical abundances of disrupted progenitors of MW-mass galaxies and their stellar mass, and the evolution of the stellar mass–metallicity relations (MZR) of this population with redshift. We find that these relations have significant scatter, which correlates with the accretion redshifts (zacc) of satellites, and with their cold gas fractions. We investigate the MZRs of dwarf populations accreted at different redshifts and find that they have similar slopes, and also similar with the slope of the MZR of the surviving population (≈0.32). However, the entire population of disrupted dwarfs displays a steeper MZR, with a slope of ≈0.48, which can be explained by the changes in the mass spectrum of accreted dwarf galaxies with redshift. We find strong relations between the (mass-weighted) 〈zacc〉 of the disrupted populations and their global chemical abundances (〈[Fe/H]〉 and 〈[Mg/Fe]〉), which suggests that chemical diagnostics of disrupted dwarfs can be used to infer the types of merger histories of their hosts. For the case of the MW, our simulations predict that the bulk of the disrupted population was accreted at 〈zacc〉 ≈ 2, in agreement with other findings. We also find that disrupted satellites form and evolve in denser environments, closer to their hosts, than their present-day counterparts.

A study on aramid nano-aerogel fiber and its fabric thermal conductivity

Aramid nano-aerogel represents an ideal structure for the fabrication of next-generation high-performance thermal insulation fibers and textiles. Single aramid nano-aerogel fiber can be achieved via wet spinning. The thermal conductivity of these fibers, a crucial determinant of textile insulation performance, remains under-explored in terms of numerical modeling. This research aims to establish a numerical inversion model to determine the thermal conductivity of single aramid nano-aerogel fiber. By simulating the three-dimensional geometry of plain fabric, the volume fraction of gas and solid within the fabrics are computed. Drawing from the law of energy conservation and Fourier's law of heat conduction, a relationship model is proposed between the thermal conductivity of single aramid nano-aerogel fiber and the overall thermal conductivity of the fabric. The finite difference method is employed to ascertain the thermal conductivity of single aramid nano-aerogel fiber. Furthermore, the influence of the geometric structure and the fiber diameter on the thermal insulation performance of the single-layer fabric is analyzed, which provides a feasible approach for the subsequent design of fabric structures with excellent thermal insulation properties.

Microstructural characterization and inductively coupled plasma-reactive ion etching resistance of Y2O3–Y4Al2O9 composite under CF4/Ar/O2 mixed gas conditions

In the semiconductor manufacturing process, when conducting inductively coupled plasma-reactive ion etching in challenging environments, both wafers and the ceramic components comprising the chamber’s interior can be influenced by plasma attack. When ceramic components are exposed to long-term plasma environments, the eroded components must be replaced. Furthermore, non-volatile reactants can form and settle on semiconductor chips, acting as contaminants and reducing semiconductor production yield. Therefore, for semiconductor processing equipment parts to be utilized, it is necessary that they exhibit minimized generation of contaminant particles and not deviate significantly from the composition of conventionally used Al2O3 and Y2O3; part must also last long in various physicochemical etching environment. Herein, we investigate the plasma etching behavior of Y2O3–Y4Al2O9 (YAM) composites with a variety of mixing ratios under different gas fraction conditions. The investigation revealed that the etching rates and changes in surface roughness for these materials were significantly less than those of Y2O3 materials subjected to both chemical and physical etching. Microstructure analysis was conducted to demonstrate the minimization of crater formation. Mechanical properties of the composite were also analyzed. The results show that the composite can be commercialized as next-generation ceramic component in semiconductor processing equipment applications.

The ALMaQUEST Survey. XIII. Understanding Radial Trends in Star Formation Quenching via the Relative Roles of Gas Availability and Star Formation Efficiency

Star formation quenching is one of the key processes that shape the evolution of galaxies. In this study, we investigate the changes in molecular gas and star formation properties as galaxies transit from the star-forming main sequence to the passive regime. Our analysis reveals that as galaxies move away from the main sequence toward the green valley the radial profile of specific star formation rate surface density (ΣsSFR) is suppressed compared with main-sequence galaxies out to a galactocentric radius of 1.5 R e(∼7 kpc for our sample). By combining radial profiles of gas fraction (f gas) and star formation efficiency (SFE), we can discern the underlying mechanism that determines ΣsSFR at different galactocentric radii. Analysis of relative contributions of f gas and SFE to ΣsSFR uncovers a diverse range of quenching modes. Star formation in approximately half of our quenching galaxies is primarily driven by a single mode (i.e., either f gas or SFE), or a combination of both. A collective analysis of all galaxies reveals that the reduction in star formation within the central regions (R < 0.5 R e) is primarily attributable to a decrease in SFE. Conversely, in the disk regions (R > 0.5 R e), both f gas and SFE contribute to the suppression of star formation. Our findings suggest that multiple quenching mechanisms may be at play in our sample galaxies, and even within a single galaxy. We also compare our observational outcomes with those from galaxy simulations and discuss the implications of our data.

Growth and static stability of bubble clouds in yield stress fluids

This study explores the growth and static stability of bubble clouds in yield-stress fluids using an experimental approach. Carbopol gels with varying concentrations and initial gas contents as well as Laponite gels are used as model yield stress fluids in our experiments. A vacuum system is exploited to generate the bubbles and control their growth in the gels. The focus of this study is on determining the maximum gas concentration which could be held trapped in the system and the critical yield number, i.e. the ratio of the yield stress to the buoyancy stress at the onset of motion. Our findings demonstrate the effect of the bubbles proximity as well as the gel structure and rheology on both the maximum gas concentration and critical yield number. Our results confirm that for higher gas fractions, the critical yield number is larger. Also, they show that the size and degree of elongation of the bubbles at the onset of motion are controlled by their proximity as well as the gel rheology. Moreover, our results reveal two different scenarios for the bubble release depending on the uniformity of the structure of the gel. In the case of low concentration Carbopol gels, characterized by uniform structures, quasi mono-dispersed bubble suspensions are formed. At a pretty high gas concentration, this might lead to a bubble cloud burst upon static instability onset. Conversely, in the case of high concentration Carbopol gels or Laponite gels, the polydisperse bubble suspensions emerge and the bubble release occurs gradually rather than suddenly. It can be associated with the heterogeneous structure of these gels stemming from their significant shear history dependence.

Characterization of multiphase flow through Venturi nozzle using gamma-ray tomography

Venturi-based differential pressure flow meters have proven to be robust and well suited to measure the flowrate of multiphase flow in combination with other measurement techniques. However, important challenges remain in order to reduce the effect of flow regime dependent measurement uncertainties from non-homogeneous flow.Understanding the complexities of multiphase flow through a Venturi is critical, not only for the Venturi flow measurement but also for the potential implications it might have on adjacent measurements affected by the constriction-induced flow perturbations.In this study, we examine the evolution of multiphase flow through a vertically oriented Venturi situated downstream of a T-bend, with a particular emphasis on the effects this might have on associated measurements within a multiphase metering context. Using Gamma-ray tomography, we conducted measurements at the inlet, throat, outlet, and downstream of the Venturi across a wide range of flow rates and Gas Volume Fractions (GVFs). We evaluated gas fraction (GF), slip, and cross-sectional distribution, quantified using measures of asymmetry and annularity.Our findings suggest that deviations between GF and GVF, relative slip velocity, annularity, and asymmetry are generally less at the outlet and downstream of the Venturi compared to the inlet and throat. Notably, annularity exhibits a greater impact than asymmetry on the estimation of bulk fractions from cord measurements.Overall, the study suggests that there may be more favorable conditions for measurements that require a homogeneous mix and less difference between GF and GVF at the outlet or a short distance downstream of the Venturi. However, despite the inlet results showing larger deviations due to inhomogeneous flow compared to the outlet and downstream, these results demonstrate a more predictable pattern in line with predictive models, offering potential benefits for the application of corrective models.

Interplay of stellar and gas-phase metallicities: unveiling insights for stellar feedback modelling with Illustris, IllustrisTNG, and EAGLE

ABSTRACT The metal content of galaxies provides a window into their formation in the full context of the cosmic baryon cycle. In this study, we examine the relationship between stellar mass and stellar metallicity (MZ*R) in the hydrodynamic simulations Illustris, TNG, and EAGLE (Evolution and Assembly of GaLaxies and their Environment) to understand the global properties of stellar metallicities within the feedback paradigm employed by these simulations. Interestingly, we observe significant variations in the overall normalization and redshift evolution of the MZ*R across the three simulations. However, all simulations consistently demonstrate a tertiary dependence on the specific star formation rate (sSFR) of galaxies. This finding parallels the relationship seen in both simulations and observations between stellar mass, gas-phase metallicity, and some proxy of galaxy gas content (e.g. SFR, gas fraction, and atomic gas mass). Since we find this correlation exists in all three simulations, each employing a subgrid treatment of the dense, star-forming interstellar medium (ISM) to simulate smooth stellar feedback, we interpret this result as a fairly general feature of simulations of this kind. Furthermore, with a toy analytic model, we propose that the tertiary correlation in the stellar component is sensitive to the extent of the ‘burstiness’ of feedback within galaxies.