Liquid Region Research Articles

Amplitude-Frequency Characteristics and Stability Regions of a Two-Layer Liquid Under Angular Vibrations of a Solid Body

The article considers the problem of nonlinear oscillations of the motion of liquids completely filling an axisymmetric cylindrical vessel moving around a horizontal axis \(O{\kern 1pt} *{\kern 1pt} Y\). The motion of each fluid is assumed to be potential and formulated in a cylindrical coordinate system. The influence of nonlinear coefficients on the characteristics of dynamic processes during finite rotational movements of the vessel is estimated and the case of forced angular oscillations of a vessel with liquids relative to a fixed axis is considered. The main nonlinear effects associated with the rotation of the diameter of the interface of liquids are also revealed. An approximate solution of the obtained non-linear equations, found by the Bubnov-Galerkin method, was used in the article. As a result of the transformation, the amplitude-frequency characteristics and stability regions of a two-layer liquid are constructed under forced angular oscillations of a round cylindrical vessel.

Crystal–melt interfaces in Mg2SiO4 at high pressure: structural and energetics insights from first-principles simulations

The interplay between crystal–melt and grain boundary interfaces in partially melted polycrystalline aggregates controls many physical properties of mantle rocks. To understand this process at the fundamental level requires improved knowledge about the interfacial structures and energetics. Here, we report the results of first-principles molecular dynamics simulations of two grain boundaries of (0l1)/[100] type for tilt angles of 30.4° and 49.6° and the corresponding solid–liquid interfaces in Mg2SiO4 forsterite at the conditions of the upper mantle. Our analysis of the simulated position time series shows that structural distortions at the solid–liquid interfacial region are stronger than intergranular interfacial distortions. The calculated formation enthalpy of the solid–solid interfaces increases nearly linearly from 1.0 to 1.4 J/m2 for the 30.4° tilt and from 0.8 to 1.0 J/m2 for the 49.6° tilt with pressure from 0 to 16 GPa at 1500 K, being consistent with the experimental data. The solid–liquid interfacial enthalpy takes comparable values in the range 0.9 to 1.5 J/m2 over similar pressure interval. The dihedral angle of the forsterite–melt system estimated using these interfacial enthalpies takes values in the range of 67° to 146°, showing a decreasing trend with pressure. The predicted dihedral angle is found to be generally larger than the measured data for silicate systems, probably caused by compositional differences between the simulation and the measurements.

A High-Temperature Superconducting Wideband Bandpass Filter at the L Band for Radio Astronomy

In order to ensure the normal operation of radio astronomy observations, an extremely sensitive receiver system needs to be equipped in front of the large radio telescope. An 8-pole wideband high-temperature superconducting (HTS) filter using a Coplanar Spiral Resonator Structure with a passband of 1160∼1670 MHz is developed to suppress strong radio interference. The filter is fabricated on a 36 mm × 14 mm YBCO HTS film, which is deposited on a 0.5 mm thick MgO substrate. The minimum insertion loss measured in the liquid nitrogen temperature region is 0.03 dB, and the first parasitic passband appears at 2600 MHz. The measured results are in good agreement with the simulations. The filter can be used in radio telescope receivers for the observation of neutral hydrogen and pulsars, as well as in high-sensitivity satellite navigation instruments.

Importance of critical point for the phase behavior of a reservoir fluid

It is a fundamental assumption behind a cubic equation of state that the phase behavior of a pure component can be expressed in terms of its critical temperature and pressure. This paper shows that the location of the critical point also for multicomponent reservoir fluids influences the phase behavior throughout the gas and liquid region. An equation of state model that matches the critical point and the saturation pressure at the reservoir temperature is likely to provide a good match of the phase behavior of a reservoir fluid at all conditions experienced during oil and gas production. An experimental critical point is seldom available for a reservoir fluid but the critical point can be estimated from correlations in the molar ratio of C7+ and lighter hydrocarbons. When PVT data exists, such estimated critical point can be used as an extra datapoint when assigning critical properties to an equation of state model. This is particularly useful as a constraint when the equation of state is to be used for gas injection enhanced oil recovery calculations. When the available PVT data is limited to a saturation point at the reservoir temperature, a reliable equation of state model can be developed by only tuning to the saturation pressure and the estimated critical point. The presented method is applicable to reservoir oils and gas condensates with a C7+ mole% of at least 10.

Fundamental Equation of State for Fluid Tetrahydrofuran

An empirical fundamental equation of state in terms of the Helmholtz energy for tetrahydrofuran is presented. In the validity range from the triple-point temperature up to 550 K and pressures up to 600 MPa, the equation of state enables the calculation of all thermodynamic properties in the liquid, vapor, and super-critical regions including saturation states. Based on an extensive literature review, experimental data are represented within their experimental uncertainty. In the homogeneous liquid phase at atmospheric pressure, the uncertainty in density is 0.015 %, speed of sound is represented with an uncertainty of 0.03 %, and isobaric heat capacity has an uncertainty of 0.4 %. Isobaric heat capacities in the homogeneous vapor phase are described with an uncertainty of 0.2 %. Higher uncertainties occur above atmospheric pressure for all homogeneous properties. Depending on the temperature range, vapor pressure can be calculated with an uncertainty from 0.02 % to 3 %. The extrapolation behavior is evaluated, showing reasonable extrapolation behavior towards extreme conditions.

Effects of heating configuration and operating parameters on heat transfer and interfacial physics of microgravity flow boiling with subcooled inlet conditions – Experiments onboard the International Space Station

This study is part of the Flow Boiling and Condensation Experiment (FBCE), a collaborative effort between the Purdue University Boiling and Two-Phase Flow Laboratory (PU-BTPFL) and the NASA Glenn Research Center. The FBCE fitted with the Flow Boiling Module (FBM) was launched to the International Space Station (ISS) in August 2021 and experiments were successfully performed from February to July 2022 to amass a large microgravity-flow-boiling database. This study is focused on heat transfer and flow visualization of microgravity flow boiling of n-Perfluorohexane in a rectangular channel of 5.0 mm height, 2.5 mm width (heated), and 114.6 mm length, with subcooled inlet conditions. High-speed-video photography is utilized to present flow patterns and temporal interfacial behavior. Heat transfer results are presented in the form of flow boiling curves and both parametric curves and streamwise profiles of wall temperature and heat transfer coefficient. Firstly, the parametric effects of mass velocity (199.4 – 3200.0 kg/m2s), inlet subcooling (0.2 – 46.0°C), and inlet pressure (124.2 – 176.7 kPa), on the aforementioned aspects are assessed for double-sided heating to establish them for a microgravity environment. Of these three parameters, mass velocity and inlet subcooling mostly determine the microgravity flow boiling behavior, while inlet pressure plays an insignificant role. Flow patterns for double-sided heating are more complex than those for single-sided heating due to interaction between the two vapor layers. Vapor interaction is minimized at high subcoolings and high mass velocities due to strong condensation offered by the subcooled bulk liquid layer separating them. Despite the different flow patterns, both single- and double-sided heating generally result in similar parametric trends and local heat transfer coefficients for similar operating conditions. Flow instabilities manifest as temporal flow anomalies and temperature oscillations, and their severity increases with increasing boiling number. Secondly, the effects of heating configuration are analyzed by comparing and contrasting several aspects of single- and double-sided heating data. The heat fluxes at which onset of nucleate boiling degradation (ONBD) and critical heat flux (CHF) occur are distinctly different for single- and double-sided heating. There exists a threshold inlet subcooling demarcating the dominance of flow acceleration and condensation effects in vapor removal from the near-wall region and replenishment of fresh liquid for boiling. Above the threshold, condensation from the near-wall region is dominant and single-sided heating yields higher heat fluxes, and below it, acceleration is dominant and double-sided yields higher heat fluxes. At mass velocity in the range of 200 – 2400 kg/m2s, the threshold inlet subcooling lies in the approximate range of 20 – 30°C (corresponding inlet quality of roughly -0.40 – -0.20).

Modeling and simulation of cryogenic propellant tank pressurization in normal gravity

The self-pressurization process of cryogenic propellant storage under a normal gravity condition often involves turbulent mixing in the liquid region and complex flow fields in the vapor region caused by heat leak into a cryogenic tank. Over time, the cryogenic tank pressurizes due to a temperature increase in the vapor phase and the heat and mass transfer across the liquid–vapor interface. A nodal simulation approach was employed to study the long term transients of tank self-pressurization. In this paper, mechanistic models and correlations were implemented to simulate the self-pressurization of Multipurpose Hydrogen Test Bed experiments with a commercial nodal code, namely, Systems Improved Numerical Differencing Analyzer with Fluid Integrator (SINDA/FLUINT). A lump number sensitivity study on the prediction of tank pressure and temperature was performed to determine the number of lumps appropriate for a 50% initial liquid fill level. Uniform heat flux boundary conditions were implemented on both phases during the tank self-pressurization with an estimated heat leak provided by NASA. Numerical simulation showed that the predicted pressure profiles of the 50% and 90% fill level cases agreed well with experimental data. In the liquid region, temperatures were primarily uniform and close to saturation due to turbulent natural convection mixing. Findings showed the current model overestimated the temperature profiles in the vapor region when assuming heat conduction transfer.

Pressure-induced evolution of stoichiometries and electronic structures of host–guest Na–B compounds

Superionic and electride behaviors in materials, which induce a variety of exotic physical properties of ions and electrons, are of great importance both in fundamental research and for practical applications. However, their coexistence in hot alkali-metal borides has not been observed. In this work, we apply first-principles structure search calculations to identify eight Na–B compounds with host–guest structures, which exhibit a wide range of building blocks and interesting properties linked to the Na/B composition. Among the known borides, Na-rich Na9B stands out as the composition with the highest alkali-metal content, featuring vertex- and face-sharing BNa16 polyhedra. Notably, it exhibits electride characteristics and transforms into a superionic electride at 200 GPa and 2000 K, displaying unusual Na atomic diffusion behavior attributed to the modulation of the interstitial anion electrons. It demonstrates semiconductor behavior in the solid state, and metallic properties associated with Na 3p/3s states in the superionic and liquid regions. On the other hand, B-rich NaB7, consisting of a unique covalent B framework, is predicted to exhibit low-frequency phonon-mediated superconductivity with a Tc of 16.8 K at 55 GPa. Our work advances the understanding of the structures and properties of alkali-metal borides.

Fluctuations of dimer heights on contracting square-hexagon lattices

We study perfect matchings on the square-hexagon lattice with 1\times n periodic edge weights and with one of the following boundary conditions: (1) each remaining vertex on the bottom boundary is followed by (m-1) removed vertices; (2) the bottom boundary can be divided into finitely many alternating line segments, each of which has a fixed positive length in the scaling limit, such that all the vertices along each line segment are either removed or retained. In case (1), we show that under certain homeomorphism from the liquid region to the upper half-plane, the height fluctuations converge to the Gaussian free field in the upper half-plane. In case (2), when the edge weights x_1,\ldots,x_n in one period satisfy the condition that x_{i+1}=O(\frac{x_i}{e^{N\alpha}}) , where \alpha>0 is a constant independent of N , we show that the height fluctuations converge to a sum of independent Gaussian free fields.

Analytical solutions for steady vertical flux through unsaturated soils with generalized hydraulic properties

In this paper, analytical solutions for one-dimensional nonlinear steady-state vertical flux through unsaturated soils are presented. The analytical solutions are applicable for homogeneous soils for which the hydraulic conductivity function is a generalized form of the well-known Brooks-Corey and rational models. The adopted generalized soil–water retention model involves two additional parameters which reflect the curvature of hydraulic functions near saturation. The main advantage of the used generalized hydraulic conductivity function is that it fits better experimental data. The soil domain is a finite-depth medium overlying a fixed groundwater level. The derived analytical solutions are obtained using the Maclaurin series expansion technique. Analytical solutions for both infiltration and evaporation are developed. For evaporation from a fixed groundwater level, the derived solutions can be used to predict the existence of a vaporization plane below the soil surface. For this case, analytical expression of the position of drying front separating liquid and gas regions is derived. The analytical results are compared to numerical ones for various infiltration and evaporation examples and excellent agreements are obtained. The generalized model is also used to fit experimental data obtained for two soils. The results show that the use of the standard Brooks-Corey model may lead to an overestimation of the position of the drying front.

Metallic glass reinforcement for the enhanced mechanical performance of oxide glass

Oxide glass/metallic glass composites have not been widely studied yet though they can have several advantages over single phase materials. In the present work glassy oxide/metallic composite materials were produced by sintering of powdered oxide glass reinforced with metallic glassy ribbons in the supercooled liquid regions. The structure, sample morphology, thermal and mechanical properties were tested. The composite samples showed better mechanical properties in comparison with single phase oxide samples.

Defect-induced ordering and disordering in metallic glasses

On the basis of shear modulus measurements on a Pt-based glass, we calculated temperature dependence of the defect concentration c using the Interstitialcy theory. This temperature dependence is compared with temperature dependence of the normalized full width at half maximum (FWHM) γ of the first peak of the structure factor S(q) for the same glass available in the literature. It is found that γ above the glass transition temperature Tg linearly increases with c in the same way for both initial and relaxed (preannealed) samples providing the evidence of defect-induced disordering in the supercooled liquid region independent of glass thermal prehistory. For both states of the samples, the derivative dγ/dc is close to unity. Below Tg, the interrelation between γ and c is entirely different for initial and relaxed samples. In the former case, strong defect-induced ordering upon approaching Tg is observed while relaxed samples do not reveal any clear ordering/disordering. Possible reasons for these observations are discussed.To further investigate the relationship between the normalized FWHM and defect concentration, we performed molecular dynamic simulation of γ(c)-dependence in a high-entropy FeNiCrCoCu model glass. It is found that γ also linearly increases with c while the derivative dγ/dc is again close to unity just as in the case of Pt-based glass.

Comparing the formation, properties and structure between Fe20Co20Ni20Cr20(P0.45B0.2C0.35)20 high-entropy metallic glass and the predecessor Fe75Cr5P9B4C7 metallic glass

In present work, formation, properties and local structure features between novel Fe20Co20Ni20Cr20(P0.45B0.2C0.35)20 high-entropy metallic glass (HEMG) and the predecessor Fe75Cr5P9B4C7 metallic glass (MG) were thoroughly characterized by experiments and ab-initio molecular dynamics (AIMD) simulation. Compared with predecessor MG, the HEMG possesses a higher thermal stability of supercooled liquid with wider supercooled liquid region of 57 K, superior corrosion resistance with higher corrosion potential, lower corrosion and passive current density along with wider passive region in 3 wt.% NaCl solution. Additionally, the HEMG possesses a paramagnetic feature with low magnetization of only 9.38 emu·g−1, while predecessor MG possesses a good soft-magnetic property with a high saturation magnetization of 115.16 emu·g−1. The corresponding local structure differences deriving from AIMD simulation exhibit that the HEMG possesses a higher content of icosahedra-like structures (with bond pair indexes (BPIs) of 1551, 1541 and 1431) and Voronoi polyhedra (VPs) with relative smaller coordination numbers (8, 9, 11, 12 and 13), lower content of crystal-type structures (with BPIs of 1421, 1422, 1441 and 1661) and VPs with larger coordination numbers (15 and 16) compared with predecessor MG. These results show that the formation, properties and local structures can be visibly changed after present high-entropy alloying by similar solvent elements Co, Ni and Cr equiatomic substitution of Fe in predecessor MG. Additionally, both alloys possess dominant VPs with coordination numbers from 12 to 15 and good ductility without fracture as bent by 180°.

Effects and mechanisms of Nb and Fe additions on glass-forming ability and magnetic properties of a Co71.5Gd3.5B25 metallic glass

Aiming to unraveling the effects and mechanisms of Nb and Fe additions on glass-forming ability (GFA) and magnetic properties, especially coercivity (Hc) on Co-based metallic glasses, 2–4 at% Nb and/or 7.15–28.6 at% Fe have been alloyed into a Co71.5Gd3.5B25 alloy by substitution of Co. The results show that alloying either Nb or Fe into the base alloy leads to enhanced stability of supercooled liquid and GFA, and bulk metallic glass (BMG) can be formed for the alloy with 4 at% Nb or 28.6 at% Fe. Combined addition of Nb and Fe further improves the thermal stability and GFA, and lowers viscosity in supercooled liquid state. A (Co0.6Fe0.4)67.5Gd3.5Nb4B25 BMG possess a wide supercooled liquid region (ΔTx) of 85 K, critical sample diameter of 3.0 mm, and minimum viscosity coefficient of 2 × 108 Pa∙s. The enrichment of Fe increases saturation magnetic flux density (Bs), Hc, and saturation magnetostriction coefficient (λs) of the (Co, Fe)-Gd-B-(Nb) metallic glasses; the addition of Nb effectively inhibits the deterioration of magnetic softness caused by Fe while reducing the Bs. The (Co0.6–0.9Fe0.1–0.4)67.5Gd3.5Nb4B25 BMGs possess good soft magnetic properties with the Bs and Hc ranging 0.43–0.69 T and 2.3–5.0 A/m, respectively. Ab initio molecular dynamics simulations indicated that alloying Fe into the Co-based metallic glasses leads to enhanced magnetic anisotropy energy. The increased magnetic anisotropy arising from enlarged λs results in the increased Hc. The combination of high GFA, large ΔTx, low viscosity, and good soft magnetic properties makes the Co-based Co-Fe-Gd-Nb-B BMGs highly promising for applications as micro electromagnetic devices produced through thermoplastic forming.

Multimode experimental band dynamics of resonant nanophotonic lattices.

Subwavelength resonant lattices provide a host of interesting spectral expressions on broadside illumination. The resonance mechanism is based on generation of lateral Bloch modes phase matched to evanescent diffraction orders. The leaky mode structure and mode count determine the spectra and the number of resonance states. Here, we study band flips and bound-state transitions in guided-mode resonant structures supporting multiple resonant modes. We present theoretical simulations and experimental results for a subwavelength silicon-nitride lattice integrated with a liquid film with adjustable boundary. The relatively thick liquid waveguiding region supports additional modes such that the first four transverse-electric (TE) leaky modes are present and generate observable resonance signatures. By varying the duty cycle of the basic lattice in experiment, the 4 bands undergo band transitions and band closures as quantified herein. The experimental results taken in the 1400-1600 nm spectral region agree reasonably well with numerical analysis.

Effects of the Si element on the microstructure and mechanical properties of an Al/FMG/SiC hybrid composite

Enhancing the mechanical properties of metal matrix composites can be achieved through the modification of the chemical composition of the matrix. However, the specific role of silicon (Si) as an important alloying element in the context of Al matrix hybrid composites simultaneously reinforced with metallic glass and ceramic particles has not been extensively studied. Therefore, this present study aimed to investigate the effects of Si element on the microstructure and mechanical properties of an Al–Si matrix composite reinforced with SiC and Fe-based metallic glass (FMG) particles. The composite was fabricated using a powder metallurgy approach. The amount of Si was selected to position the resultant alloy solidus temperature in the super-cooled liquid region of the FMG reinforcing particles. Results showed that a small amount of Si formed an Al-rich solid solution in the Al matrix, while the rest was observed as Si-rich regions in the microstructure. Adding Si to the matrix improved densification behavior and reduced porosity content during sintering, resulting in a more homogeneous distribution of reinforcing particles. The compressive yield strength and hardness of the composite with Si in its composition were 82% and 74% higher, respectively, than the same composite without Si, confirming the effectiveness of incorporating Si in the matrix.

Speeds of Sound in Binary Mixtures of Water and Carbon Dioxide at Temperatures from 273 K to 313 K and at Pressures up to 50 MPa

Knowledge of thermodynamic properties of aqueous solutions of CO2 is crucial for various applications including climate science, carbon capture, utilisation and storage (CCUS), and seawater desalination. However, there is a lack of reliable experimental data, and the equation of state (EOS) predictions are not reliable, particularly for sound speeds in low CO2 concentrations typical of water resources. For this reason, we have measured speeds of sound in three different aqueous solutions containing CO2. We report speeds of sound in the single-phase liquid region for binary mixtures of water and CO2 for mole fractions of CO2 of 0.0118, 0.0066 and 0.0015 at temperatures from 273.15 K to 313.15 K and at pressures up to 50 MPa, measured using a dual-path pulse-echo apparatus. The relative standard uncertainties of the sound speeds are 0.05 %, 0.03 % and 0.01 % at 0.0118, 0.0066 and 0.0015 CO2 mole fractions, respectively. The change in sound speeds as functions of composition, pressure and temperature are analysed in this study. We find that dissolution of CO2 in water increases its sound speeds at all conditions, with the greatest increase occurring at the highest mole fractions of CO2. Our sound speed data agree well with the limited available experimental data in the literature but deviate from the EOS-CG of Gernert and Span by up to 7 % at the lowest temperatures, highest pressures, and highest CO2 mole fraction. The new low-uncertainty sound speed data presented in this work could provide a basis for development of an improved EOS and in establishing reliable predictions of the change in thermodynamic properties of seawater-like mixtures due to absorption of CO2 gas.

Band Dynamics of Multimode Resonant Nanophotonic Lattices with Adjustable Liquid Interfaces.

Subwavelength resonant lattices offer a wide range of fascinating spectral phenomena under broadside illumination. The resonance mechanism relies on the generation of lateral Bloch modes that are phase matched to evanescent diffraction orders. The spectral properties and the total number of resonance states are governed by the structure of leaky modes and the mode count. This study investigates the effect of interface modifications on the band dynamics and bound-state transitions in guided-mode resonant lattices. We provide photonic lattices comprising rectangular Si3N4 rods with a liquid film with an adjustable boundary. The band structures and band flips are examined through numerical simulations using the rigorous coupled-wave analysis (RCWA) method and analyzing the zero-order spectral reflectance as a function of the incident angle. The band structures and band flips are examined through numerical simulations, and the influences of the refractive index and the thickness of the oil layer on the band dynamics are investigated. The results reveal distinct resonance linewidths corresponding to different refractive indices of the oil layer. Furthermore, the effect of the oil thickness on the band dynamics is explored, demonstrating precise control over the number of propagating modes within the lattice structure. Theoretical simulations and experimental results are presented for a subwavelength silicon-nitride lattice combined with a liquid film featuring an adjustable boundary. The presence of a relatively thick liquid waveguiding region enables the emergence of additional modes, including the first four transverse-electric (TE) leaky modes, which produce observable resonance signatures. Through experimental manipulation of the basic lattice's duty cycle, the four bands undergo quantifiable band transitions and closures. The experimental results obtained within the 1400-1600 nm spectral range exhibit reasonable agreement with the numerical analysis. These findings underscore the significant role played by the interface in shaping the band dynamics of the lattice structure, providing valuable insights into the design and optimization of photonic lattices with adjustable interfaces.

A study of crystallization behavior and magnetic property of Co-based alloy

The crystallization behavior and magnetic properties of Co-based alloy are investigated by DSC, XRD, TEM, VSM, and impedance analyzer. The results indicate that the non-isothermal crystallization of Co50Fe25Nb15B10 alloy has a significant glass transition with a supercooled liquid region of about 80 K. When the heat treatment is above crystallization temperature, some phases appear successively as the Co2B and (Co, Fe)21Nb2B6, and with the increase of annealing temperature, the values of coercivity Hc and saturation magnetic induction strength Bs increase correspondingly. After measuring the impedance effect of the Co-based alloy, it is found that the increase in impedance value is attributed to the decrease in magnetic anisotropy performance of the alloy, and the impedance curves of both amorphous and nanocrystalline alloys show a similar single peak trend. However, the crystallization phases after annealing form with a large size that hind the magnetization process resulting in a significant decrease of (ΔZ/Z)max value.

Quasi-static and dynamic compressive behavior of Zr-based bulk metallic glass with yttrium addition

The glass-forming ability, stress-strain relationships, and fracture characteristics of Zr60-xCu27Al8Fe5Yx (x =1, 3 and 5 at%) bulk metallic glasses are investigated under compressive strain rates ranging from 10−3 to 4 × 103 s−1 using a material testing system and split-Hopkinson pressure bar. The results show that yttrium addition leads to a broader supercooled liquid region (ΔTx) and a greater γ parameter (γ = Tx/(Tg+Tl)), particularly for x = 1 at%. For all of the tested alloys, the fracture stress increases with increasing strain rate, while the fracture strain decreases. The addition of 3 at% Y results in the highest fracture stress and an improved fracture strain. The fracture surface observations show that the fracture behavior of the BMGs is dominated by the strain rate, whereas the Y content plays only a minor role.