Liquid Pockets Research Articles

Quasi-Static Fracture Toughness and Damage Monitoring in Liquid Metal Reinforced Hybrid Composites

An experimental study is performed to investigate the quasi-static fracture toughness and damage monitoring capabilities of liquid metal (75.5% Gallium/24.5% Indium) reinforced intraply glass/carbon hybrid composites. Two different layups (G-0, where glass fibers are along the crack propagation direction; C-0, where carbon fibers are along the crack propagation direction) and two different weight percentages of liquid metal (1% and 2%) are considered in the fabrication of the composites. A novel four-probe technique is employed to determine the piezo-resistive damage response under mode-I fracture loading conditions. The effect of layups and liquid metal concentrations on fracture toughness and changes in piezo-resistance response is discussed. The C-composite without liquid metal demonstrated higher fracture toughness compared to that of the G-composite due to carbon fiber breakage. The addition of liquid metal decreases the fracture initiation toughness of both G- and C-composites. Scanning electron microscopy images show that liquid metal takes the form of large liquid metal pockets and small spherical droplets on the fracture surfaces. In both C- and G-composites, the peak resistance change of composites with 2% liquid metal is substantially lower than that of both no-liquid metal and 1% liquid metal composites.

Enhanced heat transfer in microgravity from asymmetric sawtooth microstructure with engineered cavities

Nucleate pool boiling in microgravity is influenced by stagnant vapor bubble dynamics, leading to early dryout of the heated surface compared to terrestrial conditions. The Asymmetric Sawtooth and Cavity-Enhanced Nucleation-driven Transport (ASCENT) investigation studied an engineered microstructure in a nucleate pool boiling setup aboard the International Space Station (ISS) from November 2022-January 2023. The experiment was housed in the Microgravity Science Glovebox (MSG) and used degassed FC-72 as the test liquid. The engineered microstructure consisted of repeating mm-sized 60°-30° sawtooth structures located within a hermetically sealed square ampoule as the test chamber. Experimental investigations were conducted to explore a range of input heat fluxes, ranging from 0.5 to 2.3 W/cm². The resulting vapor dynamics and heat transfer were compared against a flat baseline surface. Both surfaces contained 250 µm square cavities spaced 1-mm apart. The constrained dimensions of the square chamber severely influenced vapor bubble dynamics across the heated surface. The presence of a liquid layer beneath vapor slugs on the microstructure was observed, in contrast to the baseline surface, where no liquid layer was visually detected. The transient heat transfer coefficient from the microstructure was higher than the baseline surface as the vapor bubbles grew larger at constant heat flux due to liquid film access provided by the asymmetric ridges on the microstructure. A significant increase in the heat transfer coefficient was observed at 1.8 W/cm2, potentially due to vigorous nucleation in the observed liquid pockets along the microstructure, increasing the heat transfer coefficient from 2900 to 6200 W/m2K. Nucleation was observed at heat fluxes as low as 0.5 W/cm2 from the engineered cavities, and a quasi-steady heat transfer coefficient of 2200 W/m2K was obtained at 2.3 W/cm2 from the microstructure surface. The quasi-steady analysis also indicated that both surfaces performed similarly in microgravity and terrestrial gravity in the same experimental setup. The results demonstrate that the liquid film dynamics underneath vapor slugs influence heat transfer to a large extent in microgravity conditions.

Characterization of the Spatial Distribution of the Thermodynamic Phase Within Mixed‐Phase Clouds Using Satellite Observations

AbstractModels assume that mixed‐phase clouds consist of uniformly mixed ice crystals and liquid cloud droplets when observations have shown that they consist of clusters, or “pockets,” of ice crystals and liquid cloud droplets. We characterize the spatial distribution of cloud phase over the Arctic and the Southern Ocean using active satellite observations and determine the relative importance of collocated meteorological parameters and aerosols from reanalysis to predict how uniformly mixed mixed‐phase clouds are for the first time. We performed a multi‐linear regression fit to the data set to predict the spatial distribution of the ice and liquid pockets. Contrary to what models suggest, mixed‐phase clouds are rarely perfectly homogeneous. Our results suggest that high temperatures are associated with homogeneously mixed ice and liquid pockets. We also find that a high mixing ratio of black carbon is associated with heterogeneously mixed ice and liquid pockets.

Raman lidar-derived optical and microphysical properties of ice crystals within thin Arctic clouds during PARCS campaign

Abstract. Cloud observations in the Arctic are still rare, which requires innovative observation techniques to assess ice crystal properties. We present an original approach using the Raman lidar measurements applied to a case study in northern Scandinavia. The vertical profiles of the optical properties, the effective radius of ice crystals and ice water content (IWC) in Arctic semi-transparent clouds were assessed using quantitative ground-based lidar measurements at 355 nm performed from 13 to 26 May 2016 in Hammerfest (north of Norway, 70∘39′48′′ N, 23∘41′00′′ E). The field campaign was part of the Pollution in the ARCtic System (PARCS) project of the French Arctic Initiative. The presence of low-level semi-transparent clouds was noted on 16 and 17 May. The cloud base was located just above the atmospheric boundary layer where the 0 ∘C isotherm reached around 800 m above the mean sea level (a.m.s.l.). To ensure the best penetration of the laser beam into the cloud, we selected case studies with cloud optical thickness (COT) lower than 2 and out of supercooled liquid pockets. Lidar-derived multiple scattering coefficients were found to be close to 1 and ice crystal depolarization around 10 %, suggesting that ice crystals were small and had a rather spherical shape. Using Mie computations, we determine effective radii between ∼7 and 25 µm in the clouds for ice water contents between 1 and 8 mg m−3, respectively. The uncertainties regarding the effective radii and ice water content are on average 2 µm and 0.65 mg m−3, respectively.

Evolution dynamics of premelted polycrystalline microstructures

Below their bulk melting temperature, polycrystalline materials may exhibit the premelting phenomenon, with the grain boundaries (GB) turning into liquidlike nanofilms. This structural change has several important consequences, for example in terms of mechanical properties. We study using phase field simulations the grain evolution in the premelted polycrystal of a pure substance. The dynamics is governed by heat fluxes across the liquid films, across the liquid pockets at the triple junctions, and within the grains. Depending on the dimensionless undercooling Δ and the grain size λ, we identify different regimes. When Δ≪1, the width ρ∼δ/Δ of the liquid pockets is much larger than the atomic distance δ and the dynamics becomes independent of the free energy of the dry GBs. Then, when λ≫ρ, the premelted GBs evolve according to a curvature-driven dynamics, while the grain evolution corresponds to a usual Ostwald coarsening when the liquid pockets overlap, i.e. when λ∼ρ. Within the curvature-driven regime, the triple junctions maintain their equilibrium configuration with 2π/3 angles when λ≫ρ/Δ, while a non-equilibrium configuration develops when λ∼ρ/Δ. We analyze and confirm these effects through two-dimensional phase field simulations. We finally relate our findings to experiments on ceramics exhibiting an anisotropic abnormal grain growth. Supported by additional phase field simulations, we propose a scenario for this phenomenon based on the competition between the velocity of the quasi-liquid layer propagating along the dry GBs and the curvature-driven velocity of the already pre-melted GBs.

Unveiling growth and dynamics of liposomes by graphene liquid cell-transmission electron microscopy.

Liposome is a model system for biotechnological and biomedical purposes spanning from targeted drug delivery to modern vaccine research. Yet, the growth mechanism of liposomes is largely unknown. In this work, the formation and evolution of phosphatidylcholine-based liposomes are studied in real-time by graphene liquid cell-transmission electron microscopy (GLC-TEM). We reveal important steps in the growth, fusion and denaturation of phosphatidylcholine (PC) liposomes. We show that initially complex lipid aggregates resembling micelles start to form. These aggregates randomly merge while capturing water and forming small proto-liposomes. The nanoscopic containers continue sucking water until their membrane becomes convex and free of redundant phospholipids, giving stabilized PC liposomes of different sizes. In the initial stage, proto-liposomes grow at a rate of 10-15 nm s-1, which is followed by their growth rate of 2-5 nm s-1, limited by the lipid availability in the solution. Molecular dynamics (MD) simulations are used to understand the structure of micellar clusters, their evolution, and merging. The liposomes are also found to fuse through lipid bilayers docking followed by the formation of a hemifusion diaphragm and fusion pore opening. The liposomes denaturation can be described by initial structural destabilization and deformation of the membrane followed by the leakage of the encapsulated liquid. This study offers new insights on the formation and growth of lipid-based molecular assemblies which is applicable to a wide range of amphiphilic molecules.

Numerical modelling of porosity with combined gas and shrinkage effects in HPDC

High-pressure die casting is a manufacturing process in which near-net-shape components are produced rapidly under a pressurized environment. However, due to the relatively higher cooling rate prevailing during the process, isolated liquid pockets form at certain locations, leading to increased porosity formation. A one-dimensional deformable grid numerical model has been developed for predicting the evolution of a single pore in an elementary volume, which combines the diffusion model with the shrinkage affected growth. The model accounts for the change in pore size due to shrinkage and inter-granular growth. This model can provide predictions in representative volumes and be used for component level predictions by combining with a macroscopic model.

Experimental Guidelines to Image Transient Single-Molecule Events Using Graphene Liquid Cell Electron Microscopy.

In quest of the holy grail to "see" how individual molecules interact in liquid environments, single-molecule imaging methods now include liquid-phase electron microscopy, whose resolution can be nanometers in space and several frames per second in time using an ordinary electron microscope that is routinely available to many researchers. However, with the current state of the art, protocols that sound similar to those described in the literature lead to outcomes that can differ. The key challenge is to achieve sample contrast under a safe electron dose within a frame rate adequate to capture the molecular process. Here, we present such examples from different systems─synthetic polymer, lipid assembly, DNA-enzyme─in which we have done this using graphene liquid cells. We describe detailed experimental procedures and share empirical experience for conducting successful experiments, starting from fabrication of a graphene liquid cell, to identification of high-quality liquid pockets from desirable shapes and sizes, to effective searching for target sample pockets under electron microscopy, and to discrimination of sample molecules and molecular processes of interest. These experimental tips can assist others who wish to make use of this method.

Numerical investigations of thermodynamic states formed near a reacting, supercritical CH[formula omitted]/O[formula omitted] flame

The identification of the correct thermodynamic states forming in supercritical mixing and combustion is an important area of research in engineering. When a multi-component mixture evolves at pressures that are higher than the critical pressures of each individual component, a real-gas (RG) equation of state (EoS) must be used in order to achieve superior accuracy in the predictions. However, this may not be enough when the complex non-linear mixing allows the formation of multi-phase states. The physics and the modeling of multi-phase states occurring at supercritical conditions is the subject of many research efforts and it has already been shown to play in important role when coupled with fluid-mechanics. In this situation, the RG EoS needs to be augmented with a multi-phase model that can predict the formation of pockets of liquid and vapor in a certain region, therefore the presence of “pseudo” phases, commonly discussed in supercritical thermodynamics no longer applies. Currently, the concept of vapor-liquid equilibrium (VLE) seems to be one viable approach to describe this physics. In this paper, we focus the attention on the thermodynamic states formed in the vicinity of a supercritical CH4/O2 flame. In particular, we investigate the occurrence of multi-phase conditions that require state-of-the-art modeling in RG thermodynamics. We provide emphasis about the numerical issues that may occur when inverse thermodynamic problems are solved in presence of VLE (as for example obtaining temperature and pressure out of internal energy, density and overall mixture composition) and how they can be avoided. The VLE model is compared with the corresponding single phase (no VLE) counterpart and the results are analyzed and explained. Finally, we provide an a-posteriori method to explain the role of each component in the formation of VLE states and compare it with zero-dimensional, conventional mixing models. The idea behind this work is to establish the effect of VLE in a relatively simple, canonical configuration, as well as describe a method that helps to understand how these states are formed and how they can be predicted before-hand.

Novel optical temperature and phase change sensor based on the response of hydroxypyrene to sucrose in water ice

A novel optical temperature sensor based on the protonation states of 8- hydroxypyrene-1,3,6-trisulfonic acid trisodium, also known as pyranine, is developed and characterized. When water freezes and becomes ice, impurities create small pockets of liquid water, the sizes of which are dependent on temperature. Pyranine and sucrose are added to water as it freezes to create these pockets. Water of solvation molecules surrounding sucrose create a change in the ratio of protonated to deprotonated pyranine as a function of sucrose concentration within the liquid pockets. The protonated and deprotonated forms of pyranine emit light at 440 nm and 511 nm, respectively, which is captured with a photosensitive device. These phenomena are leveraged to create a temperature and phase change sensor within ice. The sensor is illuminated using 365 nm illumination and the fluorescence intensity ratio of the 44nm and 511nm emission peaks of pyranine is studied as a function of temperature and phase change in the range 258–293 K. By using this ratio, the temperature and phase changes within an ice block are measured in a temporally and spatially resolved manner. The temperature sensitivity within the ice phase is − 9.2 ± 0.1% K−1 which is better than conventionally used fluorescence-based temperature sensors. The pyranine and sucrose sensor is a promising candidate for an optical temperature sensor with high sensitivity within bulk ice.

A mechanical model of partially liquefied vitreous dynamics induced by saccadic eye movement within a realistic shape of vitreous cavity

The vitreous undergoes physical and biochemical changes with age. The most important of such degenerative changes is vitreous liquefaction or synchysis, in which pockets of liquid known as lacunae form in the vitreous gel. The movement mechanism and characteristics of vitreous liquefaction are quite complex. In this study, the flow dynamics of partial vitreous liquefaction (PVL) as two-phase viscoelastic-Newtonian fluid flow are investigated in the human eye. A reliable three-dimensional (3D) numerical procedure is developed for capturing the interface effects and dynamic characteristics of these two-phase complex fluid flows. In the present work, two different configurations of the PVL including liquefied pocket in the central and the posterior portions of the vitreous cavity are considered. The effects of lens indentation on the flow field and interface deformation of PVL inside the vitreous cavity are investigated. The results show that the curvature of the vitreous cavity due to the lens capsule increases shear and normal stresses in comparison with those for the PVL in a sphere as a simplified model. It is observed that the presence of lens indentation and the location of liquefied region are two factors that can produce conditions of asymmetry inside the vitreous body. In a realistic model of vitreous cavity, although the velocity magnitude inside the liquefied vitreous region increases when the liquefied pocket is in the posterior portion of the vitreous cavity, the stress values and the asymmetric condition of flow field become more significant for the liquefied pocket located close to the posterior lens curvature.

New insights in glaciers characterization by differential diagnosis integrating GPR and remote sensing techniques: A case study for the Eastern Gran Zebrù glacier (Central Alps)

In GPR profiles, ice is usually imaged as a mostly electromagnetic transparent facies. However, diffraction events, as well as internal layering, can be also observed. In some cases, the bedrock below glaciers is masked by dense diffractions usually interpreted as the effect of liquid water pockets inside the so-called warm ice. However, the actual physical meaning of such GPR facies is not always obvious, because it can be related also to mixed debris and ice deposits.We adopted a strategy well known in medical sciences and referred as “differential diagnosis” in order to infer which is the actual meaning of a high scattering facies imaged within the Eastern Gran Zebrù glacier (Central Italian Alps) and, more generally, of all the internal glacier features. In fact, in many cases, there is no direct information to limit the subjectivity of geophysical interpretation; therefore, we provide all the discriminative hypotheses based on both independent and integrated criteria including GPR attribute analysis, imaging effects, reflection analysis, GPR frequency evaluations combined with geomorphological and remote sensing data obtained by two photogrammetric UAV and thermal infrared surveys.On the basis of the differential diagnosis, we concluded that the high scattering zone embedded within the studied glacier is most likely related to a mixture of ice and debris probably formed during a past shrinking phase. Beside this case study, this approach could be helpful in other GPR glaciological surveys, in which the target is related not only to the bedrock detection, but also to a detailed analysis of the internal facies of a glacier.

In-situ microstructural control of A6082 alloy to modify second phase particles by melt conditioned direct chill (MC-DC) casting process – A novel approach

• High shear melt conditioning in the sump during direct chill casting of A6082 billet. • Novelty of maintaining 2–7 °C above alloy liquidus as the sump thermal condition. • In-situ control of solidification during casting by intensive melt shearing. • Precise tailoring of as-cast microstructure to modify second phase particles. • Potential for industries to eliminate homogenisation and use recycled Al alloys. Controlling the formation of noncompact second phase particles during direct chill (DC) casting of aluminium alloys with grain refiner addition remains challenging, as it results in energy intensive homogenisation and deformation problems. In this work, we employed a novel strategy in the DC casting of A6082 alloy to produce billets with a fine-scale dispersion of second phase particles. The strategy involves maintaining 2–7 °C above alloy liquidus as a thermal condition in the sump by in-situ melt conditioning (MC) using a rotor-stator high-shear device operated at a critical rotation speed. As a result, in-situ control of solidification behaviour is achieved to precisely tailor the as-cast microstructure. The billet grain refinement is attained by MC-DC casting without the deliberate addition of chemical grain refiners. The microstructure of the MC-DC cast billet at the critical rotation speed showed a fine-scale dendritic structure with refined secondary dendrite arm spacing (SDAS). The solidification front proceeded with a shallow sump and a corresponding shorter solidification time, higher cooling rate, higher temperature gradient, and smooth solidification rate profile. The ideal fine-scale dendrites with low SDAS divided the remaining eutectic liquid into fine-scale and isolated liquid pockets, resulting in fine-scale, compact morphology, and uniform distribution of second phase particles in the as-cast microstructure. The MC-DC casting process showed the ability to increase the cast house production rate by increasing the casting speed without bleeding the billet. The present approach could be beneficial for eliminating or reducing the homogenisation practice and may also introduce significant flexibility in using recycled Al alloys in the industry.

Accelerated chromate reduction by tea waste: Comparison of chromate reduction properties between water and ice systems

The concentration of chromium (Cr) in natural water and soil environments has gradually increased in recent decades, owing to intensive use of Cr in industry and its subsequent disposal. In this study, we performed a comparison study on chromate (Cr6+) reduction by tea waste (green tea, black tea, red tea, and chamomile) in water (25 °C) and ice (−20 °C) to develop a new strategy for environmental-friendly stabilization of hazardous Cr6+ by freezing. This study shows that the freezing process can enhance the reduction of Cr6+ by tea waste. The residual Cr6+ concentration ratios (C/C0, where C is the concentration of Cr6+ after the reaction (5 h) and C0 is the initial concentration of Cr6+ (20 μM) in the system) by tea wastes in water were in the range of 0.71 (green tea) to 0.92 (chamomile); however, the ratios dramatically decreased under the freezing process (i.e., 0.06 by green tea, 0.13 by black tea, 0.18 by red tea, and 0.08 by chamomile). According to the results obtained from the fluorescent, chromatographic, and spectroscopic analyses, under the freezing process, the enhanced reduction of Cr6+ could be explained by the freeze concentration of Cr6+, phenolic components in tea extracts, and protons in small liquid pockets in liquid-like layers (LLLs). In addition, the proposed system can efficiently purify the real Cr6+-containing wastewater (i.e., electroplating wastewater), indicating that the system will be economically feasible in cold regions (i.e., polar regions).

The effects of aging on the mechanical properties of the vitreous

The vitreous body is a viscoelastic gel-like network that fills the space between the lens and the retina in the eye. With aging, the vitreous undergoes a liquefaction process in which liquid pockets form in the gel network, thereby motivating the detachment of the vitreous from the retina in a process known as posterior vitreous detachment (PVD). The PVD process may lead to the formation of floaters and even result in partial or complete loss of vision. Experiments show that the liquefaction and the PVD processes alter the mechanical properties of the vitreous. In this work, we propose a microscopically motivated model that characterizes the changes in the mechanical properties of the vitreous due to aging. To this end, we distinguish between four vitreous states: a homogeneous vitreous, a liquefied vitreous, a vitreous that undergoes partial PVD, and a vitreous with full PVD. The model predicts the time-dependent and the steady-state response of the vitreous in each of the four states. The proposed framework is validated through a comparison with various experimental findings and captures the softening of the vitreous due to aging. We illustrate the importance of the age at which the PVD process begins and of the rate of the detachment process. In addition, we introduce a quantifiable parameter that describes the stage of PVD in the eye. Lastly, we employ our model to investigate the possibility of restoring the mechanical properties of a vitreous that has undergone PVD through the addition of reinforcing fibers to the gel. This work provides insight into the consequences of the age-related changes in the microstructure of the eye and serves as a motivation for new therapeutic measures.

Effects of Fe, Mn, chemical grain refinement and cooling rate on the evolution of Fe intermetallics in a model 6082 Al-alloy

The solidification microstructures formed in a model 6082 alloy with 0.2–1.0 wt % Fe were examined under different cooling rates and the effects of 0.5 wt % Mn and Al–5Ti–1B grain refiner addition investigated. The results were compared against Thermo-Calc, differential scanning calorimetry (DSC) and cooling curve analysis. Fe promotes primary-Al grain refinement from growth restriction and constitutional undercooling effects but increases detrimental β–(Al9Fe2Si2) intermetallic. Mn contributes to primary-Al grain refinement from growth restriction and promotes the formation of α–Al15(Fe,Mn)3Si2 at the expense of increased intermetallic content. Al–5Ti–1B inoculation not only produces the strongest refinement of primary-Al grains but also refines the Fe-intermetallics by enhancing their nucleation and restricting their growth volume in the interdendritic liquid pockets.

Liquid immiscibility in the Panzhihua intrusion, SW China: Evidence from ore textures and Fe–Ti oxide-rich globules in gabbros

Abstract The Panzhihua intrusion hosts a large Fe–Ti oxide deposit in the Permian Emeishan large igneous province (ELIP), SW China. The mechanism of such massive Fe–Ti oxide accumulation in the layered intrusion is still a matter of debate. In this study, we suggest that the ore formation occurred via density-driven liquid segregation of immiscible Fe-rich liquid, instead of simple mineral sorting of Fe–Ti oxides. Interstitial oxides and kinked plagioclase crystals reveal that the Fe–Ti oxides were crystallized in-situ after their surrounding silicate minerals. Dissolution texture of primocryst plagioclase is ubiquitous in the ores, indicating that the primocryst plagioclase grains were in disequilibrium with the surrounding melt. Fe–Ti oxide-rich globules (~38 wt% FeO) are present in the ore-barren gabbro, and likely represent solidified pockets of the immiscible Fe-rich liquid. Olivine in the Fe–Ti oxide ores occurs as primocrysts (avg. Fo = 68.5) that crystalized before the interstitial Fe–Ti oxides, or as growth rims (avg. Fo = 77.5) that crystalized after interstitial Fe–Ti oxides. The primocryst olivine was likely in equilibrium with the Panzhihua parental magma, and its composition matches well with that of the basalt (Fe2O3T = ~16 wt%) exposed near the intrusion. The olivine rim was likely in equilibrium with the residual melt produced from ~33% crystallization of the Fe–Ti oxide-rich globule. This study confirms that the ore layers are formed by the sinking of dense immiscible Fe-rich liquid to squeeze out the original silicate melt in the crystal mush, forming the (semi-)massive Fe–Ti oxide layered ores.

The Movement of CO2 Through the Frozen World of Sea Ice

Every winter, a frozen blanket known as sea ice completely covers the Arctic Ocean. For centuries, sea ice has been viewed as a solid lid on the ocean that acts as a boundary to block gases traveling between the ocean and the atmosphere. However, scientific discoveries over recent years have shown that sea ice is more like a sponge, a porous substance that is also home to microscopic life forms. The pores in sea ice are filled with very salty liquid called brine that is rich in carbon dioxide (CO2). These liquid pockets create a network of tubes or channels that move gases like CO2, similar to the way veins and arteries move blood in our bodies. In this article, you will discover how CO2 enters, exits, and is transformed in one of the harshest environments on Earth.

Idiomorphic oikocrysts of clinopyroxene produced by a peritectic reaction within a solidification front of the Bushveld Complex

Orthopyroxenite cumulates throughout the Critical Zone of the Bushveld Complex commonly contain prominent euhedral crystals of bottle-green augite, typically around 1 cm in size and surrounded by “haloes” of nearly pure plagioclase. On close examination, the augite grains can be seen to be oikocrysts, containing extensively resorbed chadacrysts of orthopyroxene, indicating an effective peritectic reaction relationship between the two pyroxenes. A detailed textural study of one such layer from the UG3 Unit in the Eastern Bushveld reveals some distinctive grain-scale features, including the presence of extensively 3D-interconnected chains of thousands of cumulus chromite grains that surround the orthopyroxene grains and extend through the augite oikocrysts. The high degree of interconnectivity is remarkable in view of the relatively low (5 vol.%) modal proportion of chromite in the sample. Other noteworthy features include zoning of the oikocrysts towards higher incompatible element contents in the rims and the presence of the plagioclase haloes around the augite oikocrysts. These haloes are essentially narrow zones devoid of orthopyroxene inclusions developed within large plagioclase oikocrysts that overgrow all the other phases. We propose a mechanism whereby the plagioclase oikocrysts grow early in communication with the main magma body within an initial crystal mush of orthopyroxene and chain-textured chromite. The clinopyroxene oikocrysts grew in the remaining pore space in such a way that dissolution of orthopyroxene occurred within a narrow few-mm wide chemical boundary layer ahead of the advancing oikocryst margin. The relative rates of crystallisation and dissolution were controlled by limited chemical diffusion through the boundary layer such that orthopyroxene grains more than a few grain diameters away showed no reaction at all. The plagioclase haloes developed as a result of continuing growth of the plagioclase oikocrysts to overtake the growing pyroxene oikocrysts, locking in the orthopyroxene-depleted boundary layer, and preserving euhedral cumulus morphologies away from the pyroxene oikocrysts. This texture represents a circumstance whereby oikocrysts in the same rock develop at different overlapping stages: plagioclase oikocrysts forming early in diffusive connection with the magma column, and clinopyroxene forming peritectic poikilitic textures within residual liquid pockets chemically isolated from the overlying magma body.

Laminar drag reduction in microchannels with liquid infused textured surfaces

Liquid infused surfaces (LIS) achieve non-wetting properties through asperity structures containing pockets of a lubricating liquid rather than air. Although studies have demonstrated several potential applications of LIS, the effect of liquid infused texture on the flow of liquid in microchannels has not been systematically addressed. The present work focuses on the effect of liquid-infused texture geometry and the infused liquid properties on the flow characteristics of a bulk fluid in rectangular and round microchannel geometries. Considering four different textured geometries of transverse ridges, longitudinal ridges, in-lined square posts and staggered squares, a detailed parametric study is presented to assess the resulting drag reduction and friction factor, expressed in terms of the Poiseuille number, on the flow in microchannels. The effect of geometrical parameters is investigated for different asperity solid fraction (ϕs), asperity height (hs) and channel thickness (H) or tube diameter (D), while the effect of the infused fluid is studied in terms of a ratio of its viscosity relative to the viscosity of the flowing bulk fluid. Based on the results of the parametric study an extension of the conventional Moody diagram for non-wetting surfaces is developed. Further, a design of experiments study is conducted to relate the drag reduction and Poiseuille number to the various governing parameters, using which conditions that maximize drag reduction are identified.