Liquid Behavior Research Articles

A capillary-induced negative pressure is able to initiate heterogeneous cavitation.

A capillarity-induced negative pressure is of general importance for understanding the phase behaviors of liquids in small pores and cracks. A unique example is the embolism in the xylem of plants and the cavitation at the limiting negative pressure generated by evaporation of water from nanocapillaries in the cell walls of leaves. In this work, by combining the effect of a capillary and cavitation together, we demonstrate with molecular dynamics (MD) simulations that capillarity is able to induce spontaneous cavitation in the presence of hydrophobic heterogeneities. Our simulation results reveal separately how the capillary generates a negative pressure and how the generated negative pressure affects the onset of cavitation. We then interpret the cavitation mechanism and determine the occurrence of cavitation as a function of the hydrophobicity of the nucleating substrates where the cavitation initiates and as a function of the hydrophilicity of the capillary tube from which the negative pressure generates. Our results reveal that the capillary-induced cavitation can be described well with a heterogeneous nucleation mechanism, within the framework of classical nucleation theory.

Manifestation of hydrodynamics in natural phenomena and technological processes

Hydrodynamics today plays an important role in understanding natural phenomena and technological processes. Mathematical description of fluid motion makes it possible to predict and analyze the behavior of liquids and gases under various conditions. Ideal liquids are convenient for mathematical calculations because they have viscosity. - Is an important aspect in analyzing the motion of fluids in nature and industry. Understanding the interaction of liquids and gases with solids is important not only for studying the properties of matter in depth, but also for practical applications in various branches of science and technology. Theoretical fluid dynamics is the foundation for understanding the laws of fluid and gas motion. Hydrodynamics is an integral part of modern engineering practice and research, ensuring the development of technologies in various fields and improving the quality of life of people around the world. When ensuring the efficient functioning of technical systems, optimizing production processes and increasing the overall productivity of enterprises, the introduction of hydrodynamic principles makes it possible to reduce energy consumption, improve equipment performance and increase the stability of production processes, which makes this science an integral part of industrial activity. Modern advances in fluid dynamics are expanding knowledge of the behavior of fluid media and gases, but also contribute to the development of innovative technologies and research methods Hydrodynamics plays a key role in scientific and technical research, influencing many aspects of everyday life and industrial development, as well as providing new knowledge and tools for modern technology and innovation.

Dark and bright soliton phenomena of the generalized time-space fractional equation with gas bubbles

<p>The objective of this work is to provide the method of getting the closed-form solitary wave solution of the fractional $ (3+1) $-generalized nonlinear wave equation that characterizes the behavior of liquids with gas bubbles. The same phenomena are evident in science, engineering, and even in the field of physics. This is done by employing the Riccati-Bernoulli sub-ode in a systematic manner as applied to the Bäcklund transformation in the study of this model. New soliton solutions, in the forms of soliton, are derived in the hyperbolic and trigonometric functions. The used software is the computational software Maple, which makes it possible to perform all the necessary calculations and the check of given solutions. The result of such calculations is graphical illustrations of the steady-state characteristics of the system and its dynamics concerning waves and the inter-relationships between the parameters. Moreover, the contour plots and the three-dimensional figures describe the essential features, helping readers understand the physical nature of the model introduced in this work.</p>

INFLUENCE OF STRUCTURE EVOLUTION AND LOAD LEVEL ON THE PROPERTIES OF CREEP AND RECOVERY CURVES PRODUCED BY A NONLINEAR MODEL FOR THIXOTROPIC VISCOELASTOPLASTIC MEDIA

This paper continues the systematic analytical study of the properties of the previously constructed nonlinear shear deformation model of thixotropic viscoelastoplastic media, which takes into account the mutual influence of deformation and structural evolution. The ability of the model to describe the behavior of liquid and solid media (solidifying/solidified) is analyzed. The focus is on the response properties of the model to stepwise loading, in particular, creep and recovery curves and curves of incremental cyclic loading. The goal is to find out what typical effects of viscoelastoplastic media the model can describe and what unusual effects/properties are generated by changes in the crosslinking degree compared to typical creep and recovery curves of structurally stable materials. A system of two nonlinear differential equations is obtained which describe the response of the system to a given loading program (not deformation program, as before), such as creep under constant load and arbitrary piecewise constant load. A general solution to the Cauchy problem for this system is constructed in explicit form for six arbitrary material parameters and an increasing material function governing the model, i.e., expressions are derived as quadratures for the shear strain and crosslinking degree as functions of time, which depend on the initial conditions and all parameters of the model and loading program. An analytical study is performed for the basic properties of the family of creep and recovery curves and the structural evolution in these processes, their dependence on time (monotonicity and convexity intervals, extrema, asymptotes, etc.), on the material parameters and function of the model, on the stress level and initial crosslinking degree of the material, and on the initial stage of loading to a given stress before creep. It was proven that creep curves always increase in time, do not have inflection points and have oblique asymptotes (although their initial portions can differ considerably from straight lines), and the crosslinking degree at constant stress (at each incremental loading step, in particular, at zero stress) is always monotonic unlike other loading modes, but can decrease or increase depending on the relationship between the stress level and the initial crosslinking degree at each incremental loading step. The model is shown to describe unusual effects observed in tests of some materials, e.g., the difference in the absolute values of strain jumps during loading and complete unloading and the opposite sign of residual strain with respect to the stress and strain signs at the creep stage. Several applicability indicators of the model were found, which can be conveniently verified using experimental data. The responses of the model to cyclic loading/unloading (creep/recovery), induced oscillations of the crosslinking degree, and their effect on the rate of plastic strain accumulation were studied.

Evidence for field induced quantum spin liquid behavior in a spin-1/2 honeycomb magnet

<p>One of the most important issues in modern condensed matter physics is the realization of fractionalized excitations, such as the Majorana excitations in the Kitaev quantum spin liquid. To this aim, the 3<i>d</i>-based Kitaev material Na<sub>2</sub>Co<sub>2</sub>TeO<sub>6</sub> is a promising candidate whose magnetic phase diagram of <b>B</b> // <b>a*</b> contains a field-induced intermediate magnetically disordered phase within 7.5 T < |B| < 10 T. The experimental observations, including the restoration of the crystalline point group symmetry in the angle-dependent torque and the coexisting magnon excitations and spinon-continuum in the inelastic neutron scattering spectrum, provide strong evidence that this disordered phase is a field induced quantum spin liquid with partially polarized spins. Our variational Monte Carlo simulation with the effective K-J<sub>1</sub>-Γ-Γ'-J<sub>3</sub> model reproduces the experimental data and further supports this conclusion.</p>

Reversible dye extraction from aqueous matrices using ammonium salt-based deep eutectic solvents

Recovery of dyes present in liquid solutions was achieved with efficiencies higher than 99 %, using deep eutectic solvents composed of tetrabutylammonium chloride and decanoic acid. The method produces a totally decolorized water. Both the reuse of the clean water and of the extracted dye is plausible via this treatment, as the colorant can be recovered from the organic phase after the liquid–liquid extraction. The solvent is physically and chemically characterized, in a wide arrange of temperatures, and its behavior in liquid–liquid equilibria with water was also studied. The process works for a broad range of dye concentrations, and with a very low consumption of solvent (optimized volumetric ratio between organic and aqueous phases was 1/16). Optimized processing times set the duration of the treatment at 20 min, including the recovery of the dye from the extracted phase. The capabilities of the solvent were tested against synthetic effluents composed by industrial dyes and auxiliary agents that typically appear on dyeing processes, maintaining efficiencies above 99 %. The deep eutectic solvents also work equally well for extracting mixtures of dyes.

Strain induced electrochemical behaviors of ionic liquid electrolytes in an electrochemical double layer capacitor: Insights from molecular dynamics simulations.

Electrochemical Double Layer Capacitors (EDLCs) with ionic liquid electrolytes outperform conventional ones using aqueous and organic electrolytes in energy density and safety. However, understanding the electrochemical behaviors of ionic liquid electrolytes under compressive/tensile strain is essential for the design of flexible EDLCs as well as normal EDLCs, which are subject to external forces during assembly. Despite many experimental studies, the compression/stretching effects on the performance of ionic liquid EDLCs remain inconclusive and controversial. In addition, there is hardly any evidence of prior theoretical work done in this area, which makes the literature on this topic scarce. Herein, for the first time, we developed an atomistic model to study the processes underlying the electrochemical behaviors of ionic liquids in an EDLC under strain. Constant potential non-equilibrium molecular dynamics simulations are conducted for EMIM BF4 placed between two graphene walls as electrodes. Compared to zero strain, low compression of the EDLC resulted in compromised performance as the electrode charge density dropped by 29%, and the performance reduction deteriorated significantly with a further increase in compression. In contrast, stretching is found to enhance the performance by increasing the charge storage in the electrodes by 7%. The performance changes with compression and stretching are due to changes in the double-layer structure. In addition, an increase in the value of the applied potential during the application of strain leads to capacity retention with compression revealed by the newly performed simulations.

(Invited) Leveraging Imaging Techniques to Accelerate the Advancement of Polymer Electrolyte Membrane Water Electrolyzers

Polymer electrolyte membrane water electrolyzers (PEMWEs) are critically needed to meaningfully incorporate clean renewable energy into our energy, transportation, and manufacturing sectors, for without this energy conversion mechanism, the intermittency of renewable energy will always pose a prohibitive cost barrier to practical use. However, in addition to overcoming the intermittency issue of renewable energy, energy storage also has the power to transform current energy infrastructure, particularly when plagued by older systems that lack modularity and flexibility. For example, electricity grids are often constrained to move electricity in and out of a jurisdiction with careful predictions based on past use and future needs. This comes at a cost when electricity must be sold at a loss to prevent a catastrophic surplus of electricity in the grid. While the potential for PEMWEs is tremendous, we must reduce their capital and operating costs in order to reach widespread adoption. In recent years, important work in the field has contributed to advancing PEMWEs in a variety of areas from new materials to flow field design; however, experimental validation, particularly spatially resolved, is necessary to take a fully informed approach to tailoring these materials and architectures.In this talk, I will discuss how we use X-ray and neutron imaging, both ex situ and operando, to provide high spatial and temporal resolution experimental performance and materials characterization for PEMWEs to inform our design process for new materials fabrication, new architectures, and operating parameters. We obtained nano-scale, 3D imaging of PEMWE catalyst layers to inform the stochastic simulations used to uncover the influence of pore size and ionomer distributions on electrical and ionic conductivities. We also used operando X-ray imaging to elucidate the influence of catalyst layer and porous transport layer interfacial conditions on liquid and gas transport behaviour. By applying neutron imaging, we elucidated the impact of temperature on the distribution heterogeneity of liquid water reactant at the catalyst layer. I will also discuss how we are using soft X-rays to perform synchrotron-based scanning transmission X-ray microscopy with absorption spectroscopy to uncover heterogeneity across performance and material characteristics for the PEMWE. Through these highly resolved techniques (in terms of time and space), we aim to advance our predictive models for designing next generation materials, interfaces, and flow configurations for high performance water electrolyzers.

Numerical Simulation of Liquid Water Behavior in PEFCs with Different GDL Wettability

The performance of polymer electrolyte fuel cells (PEFCs) is greatly influenced by internal transport phenomena. Particularly, accumulation of liquid water due to electrochemical reaction is one of the main factors that prevents the transport of oxygen and increases the concentration overpotential, and thus, quick rejection of liquid water accumulation is important issue for improving performance. This study focuses on liquid water accumulation inside gas diffusion layers (GDLs), and investigates how wettability of the substrate surface alters the liquid water behavior using numerical simulation. In this study, a numerical simulation incorporating condensation phenomena was performed using three-dimensional structure of GDL substrate obtained from CT measurements. The cell temperature and the current density were set to 40° and 0.6A/cm2, and the contact angles of the substrate was set to 60°, 110°, 150°. The simulation results showed that in the hydrophobic cases of 110°, 150°, the droplets began to move between pores to minimize their surface energy as their size grew into pore scale of the substrate. While in the hydrophilic 60° case, the liquid water condensed near the catalyst layer only moved in such a way that the thickness of the liquid water increased, and no droplet-like structure were observed. In the 150° case, the contact area between the substrate and the droplets was smaller than that in the case of 110°, and the surface energy of the droplets was assumed to be larger. It was found that the liquid water accumulation is highest at the 60° case followed by 110°, 150°. Figure 1

Influence and Optimization of Gas Diffusion Layer Porosity Distribution along the Flow Direction on the Performance of Proton Exchange Membrane Fuel Cells

Influence and Optimization of Gas Diffusion Layer Porosity Distribution along the Flow Direction on the Performance of Proton Exchange Membrane Fuel Cells

Understanding and Utilizing Droplet Impact on Superhydrophobic Surfaces: Phenomena, Mechanisms, Regulations, Applications, and Beyond.

Droplet impact is a ubiquitous liquid behavior that closely tied to human life and production, making indispensable impacts on the big world. Nature-inspired superhydrophobic surfaces provide a powerful platform for regulating droplet impact dynamics. The collision between classic phenomena of droplet impact and the advanced manufacture of superhydrophobic surfaces is lighting up the future. Accurately understanding, predicting, and tailoring droplet dynamic behaviors on superhydrophobic surfaces are progressive steps to integrate the droplet impact into versatile applications and further improve the efficiency. In this review, the progress on phenomena, mechanisms, regulations, and applications of droplet impact on superhydrophobic surfaces, bridging the gap between droplet impact, superhydrophobic surfaces, and engineering applications are comprehensively summarized. It is highlighted that droplet contact and rebound are two focal points, and their fundamentals and dynamic regulations on elaborately designed superhydrophobic surfaces are discussed in detail. For the first time, diverse applications are classified into four categories according to the requirements for droplet contact and rebound. The remaining challenges are also pointed out and future directions to trigger subsequent research on droplet impact from both scientific and applied perspectives are outlined. The review is expected to provide a general framework for understanding and utilizing droplet impact.

Improved correlations of the fuel/cladding liquid penetration rate with the out-of-pile transient database

Utilizing data from the Out-of-Pile Transient Database (OPTD), we developed advanced correlations for the cladding liquid penetration rate in metallic fuels used in sodium-cooled fast reactors (SFRs). Based on the available OPTD data, our research highlights the key role of Pu concentration in influencing the liquid penetration behavior, showing different threshold fuel-cladding interaction temperatures, with burnup playing a substantial role, particularly in fuels with a 19% Pu concentration. The penetration rate exhibits a parabolic, diffusion-limited behavior, thereby facilitating predictions of maximum liquid penetration depth over time. These correlations are significantly more accurate, under a variety of conditions, compared to existing single-parameter models, and enhance our understanding of SFR metallic fuel behavior, promoting safer and more efficient reactor operations.

Quasi-Fermi liquid behavior in a one-dimensional system of interacting spinless fermions

Quasi-Fermi liquid behavior in a one-dimensional system of interacting spinless fermions

Effects of complete slip conditions on the peristaltic pumping of a Casson nanofluid with suction and injection in a vertical channel

This study investigates the effects of complete slip conditions on the peristaltic pumping of a Casson nanofluid with suction and injection in a vertical due to the crucial role that nano liquids play in a variety of technological and medical fields, particularly in peristalsis, a mechanism that transports liquids. The Casson fluid belongs to a class of non-Newtonian fluids that, through a particular stress threshold magnitude, exhibit elastic solid behavior before changing to liquid behavior. These fluids have several uses in engineering, food preparation, drilling and other fields. After establishing the governing conservation equations, the resulting flow model is effectively simulated using the realistic assumptions of a long wavelength and a low Reynolds number. The temperature distributions, velocity, pressure rate per wavelength and nanoparticle concentration of the resulting flow problem have been solved analytically. The effects of all physical factors on temperature, velocity, concentration fields, pressure rate, frictional force and pressure gradient are graphically examined using Wolfram MATHEMATICA software. There are a variety of biofluids that cannot be classified as liquids. For example, blood contains WBC, RBC and plasma. It is essential to model biofluids (blood) as nanofluids given the physical properties of these biofluids. According to reports, one of the finest yield stress models is the Casson model, and blood exhibits a similar behavior. We took these facts into consideration when thinking about Casson nanofluid flow in a vertical layer under peristalsis. Additionally, the suction and injection mechanisms can be used to represent the exchange of carbon dioxide in bold. In order to understand how blood flows through small blood vessels, this model must be examined. The obtained results show that the Newtonian case and those found in the literature have a very good agreement. Since the liquid moves faster and more effectively when the value is increased, it becomes clear that this increases the strength of the velocity. In other words, nanoperistaltic pumps can maintain a pressure differential that increases or decreases at all operating flow rates with an increasing thermophoresis effect. Furthermore, it is obvious that the pressure reduction in a Casson fluid is greater than in a Newtonian fluid.

A Thermal Anemometry Method for Studying the Unsteady Gas Dynamics of Pipe Flows: Development, Modernisation, and Application.

A detailed study of the gas-dynamic behaviour of both liquid and gas flows is urgently required for a variety of technical and process design applications. This article provides an overview of the application and an improvement to thermal anemometry methods and tools. The principle and advantages of a hot-wire anemometer operating according to the constant-temperature method are described. An original electronic circuit for a constant-temperature hot-wire anemometer with a filament protection unit is proposed for measuring the instantaneous velocity values of both stationary and pulsating gas flows in pipelines. The filament protection unit increases the measuring system's reliability. The designs of the hot-wire anemometer and filament sensor are described. Based on development tests, the correct functioning of the measuring system was confirmed, and the main technical specifications (the time constant and calibration curve) were determined. A measuring system for determining instantaneous gas flow velocity values with a time constant from 0.5 to 3.0 ms and a relative uncertainty of 5.1% is proposed. Based on pilot studies of stationary and pulsating gas flows in different gas-dynamic systems (a straight pipeline, a curved channel, a system with a poppet valve or a damper, and the external influence on the flow), the applications of the hot-wire anemometer and sensor are identified.

Investigation on Magnetotransport Properties and Specific Heat Capacity of FeTe0.58Se0.42 Single Crystals Grown by Self‐Flux Method

A comprehensive study of magnetotransport and field‐dependent specific heat of FeTe0.58Se0.42 single crystals synthesized using the self‐flux method is reported. The transport measurement reveals the presence of Fermi liquid behavior in the normal state resistivity of the single crystals. Furthermore, the grown single crystals exhibit anisotropy and demonstrate a high value of upper critical magnetic field (HC2). The magnetoresistance exhibits a linear behavior as the magnetic field increases, suggesting the possible presence of a Dirac‐cone state. Anisotropy is also observed in magnetoresistance near the superconducting transition temperature (TC). The sign reversal of the Hall coefficient and the violation of Kohler's rules are observed, which provide evidence of the presence of multiband effects in FeTe0.58Se0.42 single crystals. Specific heat measurements confirm the bulk superconductivity in the grown single crystals. Additionally, the specific heat jump is estimated, which is approximately equal to . The magnetic field‐dependent specific heat also suggests multiband superconductivity and offers insights into the upper critical field. Furthermore, the electronic specific heat is best fitted with a two‐band model. Moreover, the field‐dependent residual Sommerfeld coefficient gives information about the superconducting pairing symmetry.

Dissolution behavior of ionic liquids for different ratios of lignin and cellulose in the preparation of nanocellulose/lignin blends

Lignin is regarded as a potential solution for boosting the strength of cellulose-based products. However, the mechanism of co-solubilization for lignin and cellulose has not been investigated. In this study, the effect of lignin content on the interaction between lignin and nanocellulose during lignin/cellulose co-dissolution was examined. The results revealed that lignin binds to nanocellulose throughout the dissolution process to limit the degradation of cellulose and to prepare nanocellulose/lignin composites. Moreover, the S units in lignin were more likely to interact with cellulose during the dissolution process, whereas the G units were more likely to condense. However, when the lignin content exceeded 30 wt%, the excess lignin created a severe condensation reaction, which led to a decrease in the lignin content bound to cellulose, resulting in an unequal dissolution of cellulose. Thus, a small amount of lignin attached to cellulose during the co-dissolution of lignin and cellulose inhibits cellulose degradation and can be utilized to create nanocellulose/lignin to extend the potential applications of nanocellulosic materials.

Numerical simulations of the dynamics of a deformable particle in a viscoelastic liquid subjected to Poiseuille flow in a cylindrical microcapillary at non-negligible inertia

The manipulation and control of particles in microfluidic devices through non-intrusive methods is pivotal in many application fields, e.g., cell focusing and sorting. Inertial microfluidics is rapidly gaining attention in the scientific community because of the considerable advantages in terms of throughput. In addition to inertia, other factors can trigger the cross-stream migration of particles in liquids undergoing pressure-driven channel flows, such as the deformability of the particles themselves and/or the viscoelasticity of the carrier fluid. For this reason, the dynamics of an initially spherical elastic particle suspended in a viscoelastic liquid subjected to pressure-driven flow in a cylindrical channel at non-negligible inertia is studied through three-dimensional arbitrary Lagrangian–Eulerian finite-element numerical simulations. The mechanical behavior of the particle is described through the neo-Hookean hyper-elastic constitutive equation, whereas the rheological behavior of the carrier liquid is described through the Giesekus model. The Reynolds number Re, measuring the relative importance of inertial and viscous forces in the tube, the elastic capillary number Cae, measuring the relative importance of liquid viscous stress and solid elastic stress, and the Deborah number De, measuring the ratio of the liquid relaxation time and the flow characteristic time, are varied. The particle migrates transversally to the flow direction until reaching a radial equilibrium position depending on Re, Cae, and De. Different dynamics are observed depending on the interplay among inertia and elasticity of both the liquid and the solid phase: one, two, or even three stable equilibrium positions can be found along the tube radius.

A Study on Heat and Flow of Viscoelastic Dielectric Liquid Over an Inclined Stretching Sheet

Exploring the behavior of viscoelastic dielectric liquids on an inclined stretching sheet involves a comprehensive mathematical analysis. Employing a Runge-Kutta-based shooting strategy, this study delves into the system's non-linear Ordinary Differential Equations (ODEs). The research investigates how physical parameters like the Prandtl number, dielectric interaction parameter, viscoelastic parameter, Grashof number, and angle of inclination influence both velocity and temperature. Through graphical representations, the study sheds light on the impact of these factors and compares its findings with existing data. This intriguing combination of dielectric liquid behaviour under varying inclinations holds significant potential applications in Mines, Materials, and Fuels.

Ternary Mixtures of Hard Spheres and Their Multiple Separated Phases

We study the liquid phase behavior of ternary mixtures of monodisperse hard spheres in solution. The interactions are modeled in terms of the second virial coefficient and can be additive hard sphere (HS) or non-additive hard sphere (NAHS) interactions. We give the set of equations that defines the phase diagram for mixtures of three components. We calculate the theoretical liquid–liquid phase separation boundary for two-phase separation (the binodal) and, if applicable, the three-phase boundary, as well as the plait points and the spinodal. The sizes of the three components are fixed. The first component (A) is the smallest one, the second component (B) is four times the size of the smallest component, and the third (C) component is three times the size of the smallest one. The interaction between the first two components is fixed, and this AB sub-mixture shows phase separation. The interactions of component C with the other two components are varied. Component C can be compatible or incompatible with components A and B. Depending on the compatibility of the components, the phase diagram is altered. The addition of the third component has an influence on the phase boundary, plait points, stability region, fractionation, and volume ratio between the different phases. When all sub-mixtures (AB, AC, and BC) show phase separation, a three-phase system becomes possible when the incompatibility among all components is high enough. The position and size of the three-phase region is dependent on the interactions between the different sub-mixtures. We study the fractionation off all components depending on specific parent concentrations.