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In this study, we performed a numerical investigation of the thermophysical properties of liquid (U, Zr) mixtures, which are particularly relevant in the context of hypothetical nuclear accidents and the formation of in-vessel coriums. To do so, atomistic simulations leveraging classical molecular dynamics and an interatomic potential developed for solid (U, Zr) structures are performed. Our methodology is first validated by comparing the predictions of our model for the melting temperature and the structure factors to experimental, phase diagram, and ab initio data. We then use the approach to evaluate the temperature and composition dependence of four fundamental properties in the context of coriums: density, heat capacity, compressibility, and viscosity. Systematic comparisons to the existing experimental data are performed and discussed. In particular, the viscosity of liquid (U, Zr) mixtures is investigated by comparing diffusion calculations and the Stokes–Einstein formula as well as the results obtained with the Green–Kubo methodology, empirical predictions, and experimental data. Notably, the viscosity of the mixtures is predicted to be significantly higher than that of the single-element liquids, which is unexpected and could have crucial consequences on the early stages of the formation and flow of in-vessel corium. [ABSTRACT FROM AUTHOR]

The superadiabatic dynamical density functional theory (superadiabatic-DDFT) is a promising new method for the study of colloidal systems out-of-equilibrium. Within this approach, the viscous forces arising from interparticle interactions are accounted for in a natural way by explicitly treating the dynamics of the two-body correlations. For bulk systems subject to spatially homogeneous shear, we use the superadiabatic-DDFT framework to calculate the steady-state pair distribution function and the corresponding viscosity for low values of the shear-rate. We then consider a variant of the central approximation underlying this superadiabatic theory and obtain an inhomogeneous generalization of a rheological bulk theory due to Russel and Gast. This paper thus establishes for the first time a connection between DDFT approaches, formulated to treat inhomogeneous systems, and existing work addressing nonequilibrium microstructure and rheology in bulk colloidal suspensions. [ABSTRACT FROM AUTHOR]

The precise determination of surface transport coefficients at liquid interfaces is critical to an array of processes, ranging from atmospheric chemistry to catalysis. Building on our prior results that highlighted the emergence of a greatly reduced surface viscosity in simple liquids via the dispersion relation of surface excitations [Malgaretti et al., J. Chem. Phys. 158, 114705 (2023)], this work introduces a different approach to directly measure surface viscosity. We use modified Green–Kubo relations suitable for inhomogeneous systems to accurately quantify viscosity contributions from fluid slabs of variable thickness through extensive molecular dynamics simulations. This approach distinguishes the viscosity effects of the surface layer vs the bulk, offering an independent measure of surface viscosity and providing a more detailed understanding of interfacial dynamics and its transport coefficients. [ABSTRACT FROM AUTHOR]

This paper reports on the effects of shear rate and interface modeling parameters on the hydrodynamic slip length (LS) for water–graphite interfaces calculated using non-equilibrium molecular dynamics. Five distinct non-bonded solid–liquid interaction parameters were considered to assess their impact on LS. The interfacial force field derivations included sophisticated electronic structure calculation-informed and empirically determined parameters. All interface models exhibited a similar and bimodal LS response when varying the applied shear rate. LS in the low shear rate regime (LSR) is in good agreement with previous calculations obtained through equilibrium molecular dynamics. As the shear rate increases, LS sharply increases and asymptotes to a constant value in the high shear regime (HSR). It is noteworthy that LS in both the LSR and HSR can be characterized by the density depletion length, whereas solid–liquid adhesion metrics failed to do so. For all interface models, LHSR calculations were, on average, ∼28% greater than LLSR, and this slip jump was confirmed using the SPC/E and TIP4P/2005 water models. To address the LS transition from the LSR to the HSR, the viscosity of water and the interfacial friction coefficient were investigated. It was observed that in the LSR, the viscosity and friction coefficient decreased at a similar rate, while in the LSR-to-HSR transition, the friction coefficient decreased at a faster rate than the shear viscosity until they reached a new equilibrium, hence explaining the LS-bimodal behavior. This study provides valuable insights into the interplay between interface modeling parameters, shear rate, and rheological properties in understanding hydrodynamic slip behavior. [ABSTRACT FROM AUTHOR]

We numerically investigate the dynamics and linear rheology of disordered systems made of patchy particles, focusing on the role of valence, temperature, and bonding mechanism. We demonstrate that the dynamics is enslaved to bonding, giving rise to an activated behavior at low temperatures. By independently computing the diffusion constant and the viscosity from the simulations, we also confirm the validity of the Stokes–Einstein relation in valence-limited systems, with two caveats: (i) the diffusion constant requires a finite-size correction, at least at the intermediate density we investigate, and (ii) there is the onset of a breakdown that appears at the lowest temperatures considered. Finally, our results show that the storage and loss moduli of mixtures of divalent and M-valent particles exhibit an apparent power-law dependence on frequency, hinting at the possibility of using the composition to finely tune the rheological response of these materials. Our results compare well with literature experimental data on valence-limited DNA nanostars. In addition, the wealth of data we present and analyze here will help develop and test theoretical frameworks aimed at describing the dynamics of flexible limited-valence particles that self-assemble into disordered networks. [ABSTRACT FROM AUTHOR]

Accurate prediction of the entrained liquid droplet fraction in an annular two-phase flow regime plays a crucial role for estimating the dryout type critical heat flux to identify the optimized flow characteristics in the thermal systems across different industries. Existing studies have provided different correlations based on the limited experimental data. However, these correlations are applicable to certain operating conditions. Therefore, the present study aims at applying a deep learning method, specifically an artificial neural network (ANN), to enhance the prediction of the entrained liquid droplet fraction. Experimental data from various works on annular flow, covering a wide spectrum of pressure and flow conditions, are utilized for training the ANN model. Eight input variables, viz, superficial gas velocity (J S G ), superficial liquid velocity (J S L ), gas viscosity (μ G), liquid viscosity (μ L), gas density (ρ G), liquid density (ρ L), pipe diameter (d) and liquid surface tension (σ L V ) are considered as input features. The entrained liquid droplet fraction is the single output feature. The present model employs the Bayesian regularization backpropagation algorithm for training. The present ANN model is compared against the performance of linear regression, decision tree and support vector machine algorithms, and found that the performance of the present Bayesian regularization neural network (BRNN) model is superior within ∼ 7.5 % deviation. Further, the BRNN model is coupled with the film mass flow rate model to obtain the axial variation of the liquid film mass flow rate and good agreement is noticed when compared against the experimental data. [ABSTRACT FROM AUTHOR]

It is shown that the transport coefficients (self-diffusion, shear viscosity, and thermal conductivity) of the Weeks–Chandler–Andersen (WCA) fluid along isotherms exhibit a freezing density scaling (FDS). The functional form of this FDS is essentially the same or closely related to those in the Lennard-Jones fluid, hard-sphere fluid, and some liquefied noble gases. This proves that this FDS represents a quasi-universal corresponding state principle for simple classical fluids with steep interactions. Some related aspects, such as a Stokes–Einstein relation without a hydrodynamic diameter and gas-to-liquid dynamical crossover, are briefly discussed. Simple fitting formulas for the transport coefficients of the dense WCA fluid are suggested. [ABSTRACT FROM AUTHOR]

Shale gas reservoirs generally have ultra-low water saturation, and the water in reservoirs is closely bound to the walls of inorganic nanopores, forming a water film structure on the hydrophilic surface. When shale gas enters the inorganic nanopores, the water films in the inorganic pores will be removed by evaporation instead of being driven away by the gas, which increases the difficulty of predicting production during shale gas extraction. Based on molecular dynamics simulations, a water film evaporation model is proposed, considering the evaporation of water films during shale gas transport and the influence of water film evaporation on the shale gas transport mechanism. The Green–Kubo method is employed to calculate the viscosity of the water film. The evaporation flux of the water film under the influence of viscosity is discussed in the evaporation model. The transport mechanisms of shale gas in nanopores and the effect of water film evaporation on shale gas transport mechanisms are analyzed in detail. The result indicates that the water films in the inorganic nanopores are constrained on the hydrophilic surface, and the viscosity normal to the surface of the water film of 4 Å is 0.005 26 Pa⋅S, which is 6.12 times the reference value of viscosity at 298 K. In the process of water film evaporation, the evaporation flux of the water film is influenced by viscosity. In the study of the shale gas transport mechanism, water films in inorganic nanopores can hinder the surface diffusion of the methane molecules adsorbed on boundary and significantly reduce the mass flux of shale gas. [ABSTRACT FROM AUTHOR]

In this study, we use molecular dynamics simulations of liquid water to investigate how shear thinning affects the viscosity of liquid water by structural changes of the hydrogen bond network. The effect of shear on viscosity can be divided into two parts: shear-induced destruction of the hydrogen bond network and the influence of the water structure on shear viscosity. First, strong shear destroys tetrahedral structures and thus reduces the connectivity of the hydrogen bond network. It is mainly because shear deformation, characterized by compression and expansion axes, respectively, triggers the destruction and formation of hydrogen bonds, resulting in anisotropic effects on water structures. At the same time, shear destroys large clusters and enhances the formation of small ones, resulting in a decrease in average cluster sizes. Second, the change of viscosity obeys a power law relationship with the change of hydrogen bond structures, highlighting a one-to-one correspondence between structure and property. Meanwhile, in order to explain why the structure affects viscosity, we define hydrogen-bond viscosity and find that the cooperative motion of the water structures can promote momentum transfer in the form of aggregations. Hydrogen-bond viscosity accounts for 5%–50% of the total viscosity. Our results elucidate that water structures are the important structural units to explain the change of water properties. [ABSTRACT FROM AUTHOR]

The chemical composition and physical properties of secondary organic aerosol (SOA) generated through OH-initiated oxidation of mixtures containing β-myrcene, an acyclic monoterpene, and d-limonene, a cyclic monoterpene, were investigated to assess the extent of the chemical interactions between their oxidation products. The SOA samples were prepared in an environmental smog chamber, and their composition was analyzed offline using ultraperformance liquid chromatography coupled with electrospray ionization high-resolution mass spectrometry (UPLC-ESI-HRMS). Our results suggested that SOA containing β-myrcene showed a higher proportion of oligomeric compounds with low volatility compared to that of SOA from d-limonene. The formula distribution and signal intensities of the mixed SOA could be accurately predicted by a linear combination of the mass spectra of the SOA from individual precursors. Effects of cross-reactions were observed in the distribution of isomeric oxidation products within the mixed SOA, as made evident by chromatographic analysis. On the whole, β-myrcene and d-limonene appear to undergo oxidation by OH largely independently from each other, with only subtle effects from cross-reactions influencing the yields of specific oxidation products.

The ice surface is known for presenting a very small kinetic friction coefficient, but the origin of this property remains highly controversial to date. In this work, we revisit recent computer simulations of ice sliding on atomically smooth substrates, using newly calculated bulk viscosities for the TIP4P/ice water model. The results show that spontaneously formed premelting films in static conditions exhibit an effective viscosity that is about twice the bulk viscosity. However, upon approaching sliding speeds in the order of m/s, the shear rate becomes very large, and the viscosities decrease by several orders of magnitude. This shows that premelting films can act as an efficient lubrication layer despite their small thickness and illustrates an interesting interplay between confinement enhanced viscosities and shear thinning. Our results suggest that the strongly thinned viscosities that operate under the high speed skating regime could largely reduce the amount of frictional heating. [ABSTRACT FROM AUTHOR]

Understanding polymer transport in nanopores is crucial for optimizing heterogeneously catalyzed processes in polymer upcycling and fabricating high-performance nanocomposite films and membranes. Although confined polymer dynamics have been extensively studied, the behavior of polyethylene (PE)—the most widely used commodity polymer—in pores smaller than 20 nm remains largely unexplored. We investigate the effects of extreme nanoconfinement on PE transport using capillary rise infiltration in silica nanoparticle packings with average pore radii ranging from ∼1 to ∼9 nm. Using in situ ellipsometry and the Lucas–Washburn model, we discover a previously unknown inverse relationship between effective viscosity (ηeff) and average pore radius (Rpore). Additonally, we determine that PE transport under these extreme conditions is primarily governed by physical confinement, rather than pore surface chemistry. We refine an existing theory to provide a generalized formalism to describe the polymer transport dynamics over a wide range of pore radii (from 1 nm and larger). Our results offer valuable insights for optimizing catalyst supports in polymer upcycling and improving infiltration processes for nanocomposite fabrication. [ABSTRACT FROM AUTHOR]

Many microorganisms propel themselves through complex media by deforming their flagella. The beat is thought to emerge from interactions between forces of the surrounding fluid, the passive elastic response from deformations of the flagellum and active forces from internal molecular motors. The beat varies in response to changes in the fluid rheology, including elasticity, but there are limited data on how systematic changes in elasticity alter the beat. This work analyses a related problem with fixed-strength driving force: the emergence of beating of an elastic planar filament driven by a follower force at the tip of a viscoelastic fluid. This analysis examines how the onset of oscillations depends on the strength of the force and viscoelastic parameters. Compared to a Newtonian fluid, it takes more force to induce the instability in viscoelastic fluids, and the frequency of the oscillation is higher. The linear analysis predicts that the frequency increases with the fluid relaxation time. Using numerical simulations, the model predictions are compared with experimental data on frequency changes in the bi-flagellated alga Chlamydomonas reinhardtii. The model shows the same trends in response to changes in both fluid viscosity and Deborah number and thus provides a possible mechanistic understanding of the experimental observations.

We report measurements of the shear viscosity η in water up to 150 MPa and down to 229.5 K. This corresponds to more than 30 K supercooling below the melting line. The temperature dependence is non-Arrhenius at all pressures, but its functional form at 0.1 MPa is qualitatively different from that at all pressures above 20 MPa. The pressure dependence is non-monotonic, with a pressure-induced decrease of viscosity by more than 50% at low temperature. Combining our data with literature data on the self-diffusion coefficient Ds of water, we check the Stokes-Einstein relation which, based on hydrodynamics, predicts constancy of Dsη/T, where T is the temperature. The observed temperature and pressure dependence of Dsη/T is analogous to that obtained in simulations of a realistic water model. This analogy suggests that our data are compatible with the existence of a liquid-liquid critical point at positive pressure in water. [ABSTRACT FROM AUTHOR]

Water is a unique and abundant substance in biological and chemical systems. Considering its importance and ubiquity, numerous water models have been developed to reproduce various properties of bulk water in molecular simulations. Therefore, selecting an appropriate water model suitable for the properties of interest is crucial for computational studies of water systems. The four-point Optimal Point Charge (OPC) and three-point OPC (OPC3) water models were developed in 2014 and 2016, respectively. These models reproduce numerous properties of bulk water with high accuracy, such as density, dielectric constant, heat of vaporization, self-diffusion coefficient, and surface tension. In this study, we evaluated the shear viscosities of the OPC and OPC3 water models at various temperatures ranging from 273 to 373 K using the Green–Kubo formalism to assess their performance. The evaluated viscosities of both models were very close to each other at all the examined temperatures. At temperatures above 310 K, the calculated shear viscosities were in excellent agreement with the experimental results. However, at lower temperatures, the water models systematically underestimated the shear viscosity, with the calculated values at 273 and 298 K being 20% and 10% lower than the experimental values, respectively. Despite this limitation, the OPC and OPC3 water models outperformed other widely used water models. [ABSTRACT FROM AUTHOR]

Understanding factors that affect the clustering and association of antibodies molecules in solution is critical to their development as therapeutics. For 19 different monoclonal antibody (mAb) solutions, we measured the viscosities, the second virial coefficients, the Kirkwood-Buff integrals, and the cluster distributions of the antibody molecules as functions of protein concentration. Solutions were modeled using the statistical-physics Wertheim liquid-solution theory, representing antibodies as Y-shaped molecular structures of seven beads each. We found that high-viscosity solutions result from more antibody molecules per cluster. Multi-body properties such as viscosity are well predicted experimentally by the 2-body Kirkwood-Buff quantity, G22, but not by the second virial coefficient, B22, and well-predicted theoretically from the Wertheim protein-protein sticking energy. Weakly interacting antibodies are rate-limited by nucleation; strongly interacting ones by propagation. This approach gives a way to relate micro to macro properties of solutions of associating proteins.

This paper studies the instability of a non-ideal pipe system conveying fluid. Unlike ideal modeling, three types of possible non-ideal factors have been considered in the present analysis. The pipe has a crack and is subjected to boundary relaxation, and the fluid in the pipe is viscous. It is an interesting instability problem of a fluid-structure system with multiple forms of imperfections. It gains motivation from our previous study and aims at further essential results for comprehensively understanding the nature of such a problem. In order to incorporate multiple imperfections, a new data-driven approach is developed to model the non-ideal pipe-fluid system. Then the influences of the support stiffness, fluid–solid mass ratio, crack, and fluid viscosity on the pipe instability are systematically discussed. Results show that the pipe exhibits flutter-divergence conversion at low mass ratios and flutter-mode transition at high mass ratios. Due to the two types of instability transitions, the critical flow speed could experience multiple sudden jumps as the support stiffness changes. With the imperfections of crack and viscous flow, the pipe's instability behavior tends to be more complicated, but the inducing mechanisms for the sudden changes are straightforward. They are instability-type conversion, instability-mode transition, and laminar-turbulent flow transition. [ABSTRACT FROM AUTHOR]

Aim is to explore the breadmaking potential for gluten‐free goods of non‐conventional starches from Andean crops ahipa, oca, and arracacha. Their characteristics and performance in breadmaking are compared with those of cassava, taken as a reference for conventional gluten‐free root starch. Physicochemical properties of breads are studied along with the pasting and thermal properties, composition, and α‐amylase hydrolysis of starches. Arracacha starch has the lowest amylose content (2.4%) and the highest water hydration (1.4 g g−1). Its batter shows adequate proofing, but the bread is highly adhesive, with dense crumb. Ahipa starch paste has the lowest peak, trough and final viscosities determined by rapid visco analyzer, and the highest hydrolysis rate (kRVA = 2.30 min−1). Its batter exhibits, along with oca, the highest volume increase during fermentation (193–197%), but structure collapses in the oven and no alveoli are observed in the crumb. Conversely, oca forms a crumb structure similar to cassava, but with higher cell density (131 alveoli cm−2), cohesiveness (0.95), and resilience (0.65) than the latter (71 alveoli cm−2, 0.88, and 0.45, respectively). Oca starch has lower pasting temperature (64 °C) and the starch paste has similar hydrolysis rate (kRVA = 1.92 min−1) compared to cassava (71.9 °C and 2.08 min−1, respectively), making it a suitable option for providing gluten‐free yeast‐leavened breads with improved technological properties and a comparable glycemic index. [ABSTRACT FROM AUTHOR]

Exudate and its viscosity are critical in wound healing. Changes in viscosity can interfere with dressings properties as well as affect the diffusion of immune cells, nutrients, oxygen and bacteria. Current international standards for laboratory testing of wound dressings use a single low‐viscosity solution, named as ‘Test Solution A’, which fails to simulate the diverse range of exudates encountered clinically. This study employs rheological analysis to characterise exudates viscosity, comparing cattle‐derived samples to the test solution A. Results reveal non‐Newtonian, shear‐thinning behaviour in exudates, contrasting with the Newtonian behaviour of the test solution A. Although clinically classified as ‘seropurulent’, three exudate samples analysed at 37°C present with different viscosity at various shear rates, ranging from 30.8 (±14.7) to 6.5 (±1.9) mPas. Findings show that the current tests on dressings employing Test Solution A are missing the complexity of real exudates. [ABSTRACT FROM AUTHOR]

Two new cationic meso-thiazolium-BODIPY-based water-soluble and red-shifted fluorescent probes were constructed for the first time. They can monitor cellular viscosity in dual organelles and show aggregationinduced emission (AIE), which is ascribed to the efficient restricted rotation of meso-thiazolium in viscous or hindered systems. Probe 3 with an N-benzyl group shows better AIE as compared to probe 2 with an N-methyl group. [ABSTRACT FROM AUTHOR]

An accurate prediction of non-isothermal gas–liquid interfaces in cryogenic two-phase flows is crucial for the high-efficiency energy storage, transportation, and utilization of liquid hydrogen. However, temperature difference and interfacial mass and energy transport can change the thermodynamic state of gas–liquid interfaces and thereby impact the distribution. And the lower surface tension coefficient and viscosity of liquid hydrogen, compared to room-temperature fluids, increase the likelihood of the instability and breakage of non-isothermal interfaces. Conventional numerical methods suffer from a scarcity of precision and the propagation of spurious velocities in predicting such flows. In this study, a new numerical framework called cryoFoam was developed based on an open source CFD code OpenFOAM to address the issue of the inaccurate capture of non-isothermal cryogenic interfaces. A practical interface-capturing model involving phase change was implemented to achieve the uniform distribution of surface forces in both gas and liquid phases. The tangential surface force was incorporated into the governing equations to realize thermocapillary convection. The Schrage model, a widely-used phase change model, was employed to deal with condensation and evaporation. The performance of the solver was assessed using five benchmarks which involve thermocapillary flows and phase changes in liquid hydrogen, liquid oxygen, liquid nitrogen, and liquid methane. The results show that the new method can reduce large spurious velocities and prevent the distortion of isotherms near the curved interface in cryogenic fluids. It demonstrates higher precision than the traditional VOF method in predicting cryogenic thermocapillary convection and interfacial energy transport. • A new CFD code was developed to model the non-isothermal two-phase flows in liquid hydrogen. • A practical interface-capturing model involving phase change was implemented. • The tangential surface force was employed to realize thermocapillary convection. • Spurious velocities and the distortion of isotherms in liquid hydrogen were reduced. • The method presents high accuracy in predicting mass and energy transport at cryogenic interfaces. [ABSTRACT FROM AUTHOR]

Deep eutectic solvents (DESs) are increasingly recognized as sustainable alternatives suitable for a range of industrial applications. A precise comprehension of their properties is important for progress in science and engineering. In this study, we synthesized four novel ternary DESs using mandelic acid and measured their densities and viscosities at temperatures ranging from 298 to 353 K. Subsequently, an artificial neural network model was developed to predict DES density and viscosity based on temperature, critical properties, acentric factor, and molar ratio. The neural network parameters were optimized using experimental data from synthesized DESs and literature sources, both collectively over 500 data points for density and viscosity. Additionally, we investigated the influence of input parameters on model accuracy and assessed their significance. The results show that the average percentage relative error was 0.501 for density and 4.81 for viscosity. This research helps advance science and engineering applications of DESs. [ABSTRACT FROM AUTHOR]

We consider the new boundary value problem for the generalized Boussinesq model of heat transfer under the inhomogeneous Dirichlet boundary condition for the velocity and under mixed boundary conditions for the temperature. It is assumed that the viscosity, thermal conductivity and buoyancy force in the model equations, as well as the heat exchange boundary coefficient, depend on the temperature. The mathematical apparatus for studying the inhomogeneous boundary value problem under study based on the variational method is being developed. Using this apparatus, we prove the main theorem on the global existence of a weak solution of the mentioned boundary value problem and establish sufficient conditions for the problem data ensuring the local uniqueness of the weak solution that has the additional property of smoothness with respect to temperature. This article is part of the theme issue 'Non-smooth variational problems with applications in mechanics'. [ABSTRACT FROM AUTHOR]

Traditionally, intensive thermal treatments are applied to process soy beverages, negatively impacting product quality by reducing solubility, and viscosity, while promoting syneresis. Modified cassava starches can prevent these effects. This study evaluates the influence of adding modified cassava starches on syneresis, apparent viscosity, particle size, microstructure, and sensory acceptance of a fermented soy beverage. A commercial culture of starter microorganisms and probiotics is used in the fermentation. Four beverages are produced: one with native cassava starch, one with octenyl succinic anhydride (OSA)‐modified cassava starch, one with crosslinked acetylated distarch adipate (ADA), and one with crosslinked‐substituted cassava starch (mixed); the starch concentration is 1% in each beverage. Samples are stored for 3 weeks at 4 °C. Modified cassava starches significantly alters syneresis compared to the native starch beverage, with no difference among the other treatments. Viscosity shows significant differences among treatments. During storage, the native starch beverage shows an increase in syneresis and a reduction in viscosity, whereas the OSA‐modified starch beverage has higher viscosity but presents significant variation by the end of the 3‐week storage period. The mixed starch beverage has intermediate characteristics with high viscosity and stability during storage. In the sensory evaluation, the consumers prefer the OSA‐modified starch beverage. [ABSTRACT FROM AUTHOR]

Background: Synovial fluid (SF) is often used for diagnostic and research purposes as it reflects the local inflammatory environment. Owing to its complex composition, especially the presence of hyaluronic acid, SF is usually viscous and non-homogeneous. The presence of high-molar-mass hyaluronan in this fluid gives it the required viscosity for its function as a lubricant. Viscosity is the greatest major hydraulic attribute of the SF in articular cartilage. Methods: Empirical modeling of previously published results was performed. In this study, we explored the flow of a non-Newtonian fluid that could be used to model the SF flow. Analyzing the flow in a simple geometry can help explain the model's efficacy and assess the SF models. By employing some viscosity data reported elsewhere, we summarized the dynamic viscosity values of normal human SF of the knee joints in terms of time after injecting hyaluronidase (HYAL) at 25°C. The suggested quadratic behavior was obtained through extrapolation. For accurate diagnosis or prediction, the comparison between three specific parameters (ai, t0, and ln η0) was made for normal and pathological cases under the same experimental conditions for treatment by addition of HYAL and for investigation of the rheological properties. A new model on the variation of viscosity on the SF of knee joints with time after injection of HYAL with respect to normal and postmortem samples at different velocity gradients was proposed using data previously reported elsewhere. Results: The rheological behavior of SF changes progressively over time from non-Newtonian to a Newtonian profile, where the viscosity has a limiting constant value (η0) independent of the gradient velocity at a unique characteristic time (t0 ≈ 8.5 h). The proposed three-parameter model with physical meaning offers insights into future pathological cases. The outcomes of this work are expected to offer new perspectives for diagnosis, criteria, and prediction of pathological case types through comparisons with new parameter values treated under the same experimental conditions as HYAL injection. This study also highlights the importance of HYAL treatment for better intra-assay precision. [ABSTRACT FROM AUTHOR]

The study was conducted on the impact of thermophysical properties on eflornithine drug solute–solvent interactions in aqueous ethyl acetate and acetone at different concentrations and temperatures. The aim of this study is to enhance the understanding of eflornithine's behavior in different solvents, which is crucial for its effective use in pharmaceutical applications. The density, molar volume, viscometric, and conductometric characteristics of the eflornithine drug solutions (0.025, 0.05, 0.075, 0.1, and 0.125 mol/kg) in acetone and 25% (v/v) aqueous ethyl acetate were measured within a temperature range of 298.15 K–318.15 K. Based on the determined density parameters, the following parameters were assessed: viscosity (η), equivalent molar conductance, limiting apparent molar volume (V0φ), apparent molar volume of transfer (V0φtr), and apparent molar volume (Vφ). The Masson empirical relationship and the viscosity-to-Jones-Dole (JD) equation were used to evaluate the partial molar volume (Vφ), experimental slope (SV), viscosity, and density data. Temperature and concentration were used to determine each parameter. For each set of dilutions, conductometric studies were conducted in both study solvents. The gathered data was analyzed in order to evaluate the ion–solvent interactions. The Walden product Λomηo's positive temperature coefficient values indicate that the drug eflornithine functions as a structural modifier in acetone and aqueous acetyl acetate systems. The structure-making and breaking characteristics of the polar solvents acetone and ethyl acetate were identified. [ABSTRACT FROM AUTHOR]

The relationship between saturate, aromatic, resin, and asphaltene (SARA) contents and asphalt properties remains unclear. This study aimed to propose a high‐throughput molecular dynamics simulation framework and demonstrate its application in rapidly building asphalt molecular models of various SARA ratios and predicting their properties, using density as an example. Based on the framework, 400 models with varying SARA ratios with different aging degrees were generated to calculate their densities and used to train machine learning algorithms. The ordinary least squares model achieved R2 values exceeding 80%, and quantitative formulas linking asphalt density to SARA ratios were derived. It was found that saturate content negatively correlates with asphalt density, while resin content positively correlates with asphalt density. Additionally, asphalt density and viscosity increase with aging, influenced simultaneously by the SARA ratio and aging degree. Overall, this paper creates a rapid, high‐throughput molecular simulation pathway to predict asphalt behavior. [ABSTRACT FROM AUTHOR]

AbstractHeavy oil in this work is typical acidic heavy oil with acid number larger than 1, which is prone to form W/O emulsions with high viscosity and cause low oil recovery factor during water flooding. In order to further improve oil recovery of acidic heavy oil after water flooding, this paper proposed the in situ O/W emulsion flooding to conversely transform W/O emulsions into O/W emulsion with lower viscosity. Firstly, emulsion system compounding (SDS:L5 = 1:1) named ISEMF was comparatively obtained, which could decrease IFT into magnitude of 10−2 mN/m and inversely form stable O/W emulsions with low viscosity. The emulsion evaluation experiment indicated that W/O emulsion would be reversed into O/W emulsions when ISEMF concentration and water content were larger than 0.4% and 30%. Core displacement experiments showed recovery factor increment firstly increased and then decreased with permeability, and there was optimal permeability range for in situ emulsion flooding. The main reason was that much lower or larger permeability was not beneficial to good matching of emulsion droplet and pore throat. In addition, it was found that the displacement efficiency of in situ O/W emulsion flooding was better than that of surfactant flooding under the same conditions, which further validate excellent EOR performance of in situ O/W emulsion flooding for acidic heavy oil. [ABSTRACT FROM AUTHOR]

The viscosity of the same natrium-based bentonite produced by different manufacturers varies greatly when the self-setting mortar is prepared with the same ratio. The essence of the viscosity is caused by the discordant microstructure of the material. Based on SEM, XRD, EDS and NMR microscopic tests, the same bentonite produced by two different manufacturers and its self-coagulated mortar were analyzed, and the viscosity microscopic mechanism was studied. The main conclusions are as follows: a) For the two bentonite grout, the viscosity is thixotropic. The establishment of "card palace" and the formation of Q4 structure will increase the viscosity, while shear will destroy the microstructure and reduce the viscosity. The content of bentonite montmorillonite from Xiangyuan is higher than that from Yulong soil, so its slurry viscosity is higher than that from Yulong soil as a whole. b) Agitation and low shear promote the dispersion of montmorillonite particles in small lamella. The more the dispersion of small lamella, the higher the viscosity of bentonite slurry after stopping shearing. c) For bentonite self-coagulant slurry, its viscosity changes mainly depend on the degree of internal charge adsorption and hydration reaction, and the C-SH gel generated by hydration reaction can promote the increase of slurry viscosity. d) The calcium carbonsulphosilicate generated in the process of condensation is not conducive to the formation of C-S-H gel. The content of calcium carbonsulphosilicate in Xiangyuan soil mortar is higher than that in Yulong soil mortar, so its overall viscosity is lower than that in Yulong soil mortar. [ABSTRACT FROM AUTHOR]

Ionic liquids (ILs) are potentially alternative solvents for cellulose dissolution. In this article, effect of hemicellulose in cellulose dissolution in ILs and the regeneration process were investigated. Hardwood pulps were produced by kraft (KP) and pre-hydrolysis kraft (PHKP) processes. The α-cellulose and residual pentosan contents were 95.6 % and 4.2 % in PHKP and 84.3 % and 9.9 % in KP, respectively. Both pulps were dissolved in 1-butyl-3-methylimidazolium chloride [C4mim]Cl, 1-butyl-3-methylimidazolium acetate [C4mim]CH3CO2 and their double salt (DSIL), [C4mim](CH3CO2)0.6Cl0.4 at 90 °C. It was observed that PHKP had slightly higher solubility in both ILs and DSIL. The dissolved pulps were regenerated by water and characterized by FTIR, TGA, X-ray diffraction, and viscosity. Regenerated pulp film formed smooth and homogenous surface. The viscosity of regenerated PHKP was higher than the original PHKP, which affected the strength of the produced cellulose film. As observed in FTIR, the regenerated cellulose showed a stronger absorption band at 1,647 cm−1 corresponding to the C–O stretching vibration of C–O–H. The crystalline structures of regenerated KP and PHKP from [C4mim](CH3CO2)0.6Cl0.4 changed to cellulose II form from the original cellulose I form. [ABSTRACT FROM AUTHOR]

This study aims to assess the lower limit of porosity that can be achieved in freeze‐cast sintered lithium titanate (LTO) materials while maintaining the characteristic pore directionality. LTO materials were fabricated with solid loading varying in the range of 30–37 vol.%. Sucrose and cationic dispersant were used to vary viscosity and total solute concentration in the aqueous LTO suspensions. Two series of suspension compositions were selected for freeze‐casting. In one series, aqueous suspensions were prepared by mixing deionized (DI) water, sucrose, and LTO powder, while in the other series, aqueous suspensions were prepared by mixing DI water, sucrose, cationic dispersant (1‐hexadecyl)trimethylammonium bromide (CTAB), and LTO powder. With increasing solid loading from 30 to 37 vol.%, porosity in the sintered materials decreased from about 50 to 36 vol.%. LTO materials fabricated from suspensions containing sucrose exhibited well‐developed characteristic freeze‐cast microstructure. Unexpectedly, LTO materials fabricated from suspensions containing sucrose and dispersant exhibited cellular pore morphology irrespective of the solid loading. Sample height had an impact on microstructure evolution in the transition zone and zone length. With the increasing solid loading from 30 to 37 vol.%, the compressive strength of sintered LTO materials having the characteristic freeze‐cast microstructure increased from about 110 to 240 MPa. [ABSTRACT FROM AUTHOR]

In various systems of energy, such as turbo-machinery and viscous-lock system, squeeze film plays a crucial role for improving transport systems. The importance of the aforementioned applications led us to explore the physical behavior of Rabinowitsch fluid flow for several values of viscosity, Q ∈ [ 0 − 1 ] , load capacity (W ∗) , nonlinear factor, ω = [ − 2 × 1 0 − 4 , 0 , 2 × 1 0 − 4 ] , dimensionless film thickness (h ∗) , dimensionless radius of the capillary tube (R 0 ∗) , dimensionless thickness of porous pad (H 0 ∗ = 0 , 0. 1 , 0. 2), inner and outer radius ratio (Ω = 0 , 0. 2 , 0. 4) , roughness parameter (c ∗ = 0 , 0. 1 , 0. 2 , 0. 3 , 0. 4) through a squeeze film with two rough porous annular discs. Five-point Gauss quadrature integral formula has been used to examine the characteristics of annular discs, and small perturbation method has been used to discretize the governing Rabinowitsch fluid flow (RFF) equations. The modified Reynolds equation for rough, porous and viscosity change with film thickness is developed using Christensen's stochastic theory, modified Darcy's theory and the association between viscosity and film thickness agreement. The impacts of ω on the behavior of porosity and viscosity variability of RFF have been visually depicted in terms of film pressure, load capacity and squeeze reaction time of annular discs. It has been determined that for RFF with variable viscosity and roughness parameter on a porous media, the performance of the annular disks enhances for ω = − 2 × 1 0 − 4 (dilatant lubricant), and diminishes for ω = 2 × 1 0 − 4 (pseudo-plastic lubricant). It has been found that the film pressure in case of dilatant lubricant is increased by the influence of Rabinowitsch fluids on porous walls, but the behavior of pseudo-plastic lubricants has an opposite tendency relative to Newtonian lubricants. It has also been found that the impact of variability in porosity, roughness and viscosity diminishes the load-carrying capacity (LCC) with increased film thickness than the case of nonporous, smooth surface and constant viscosity of Rabinowitsch fluid. [ABSTRACT FROM AUTHOR]

Various stress-releasing phenomena, such as episodic tremor and slip (ETS) and low-frequency earthquakes, occur at the downdip seismogenic zone in southwest Japan. However, it is unclear how much net stress and slip deficit accumulate at these depths during the interseismic phase. Here, we perform both elastic and viscoelastic earthquake-cycle forward models and reassess the locking state in Nankai from a synthesized perspective with the aid of geodetic modeling results. Our results suggest that the overestimation of the locking depth due to ignoring Earth's viscoelasticity is much smaller (less than 5 km) in this early interseismic subduction zone compared to that (~ 10 km) of late-interseismic margins. Considering viscoelastic modeling results and other physical arguments, the preferred steady-state viscosities for the continental and oceanic mantle are 5 × 1019 Pa s and 1020 Pa s, respectively. We find a clear trade-off between the full locking depth and the width of the transition zone when explaining both horizontal and vertical geodetic data, demanding other data to further resolve this inherent ambiguity. Unlike in Cascadia, partial megathrust locking in Nankai likely penetrates into the ETS zone, leaving no intervening gap between the shallow megathrust, where hosts large earthquakes, and the ETS zone. Assuming locking extends into the downdip of the ETS zone (i.e., 40 km), we propose a preferred viscoelastic locking model with a full locking depth of 18 km and a broad transition zone spanning a 22-km depth range. In this model, the downdip half portion of the transition zone corresponds to the ETS zone, which can accumulate certain slip deficit in a largely creeping and partially locked state. However, most of the accumulated slip deficit in the ETS zone may be accommodated aseismically simultaneously by stress-releasing phenomena, leaving limited to no budget to release during future megathrust earthquakes. We suggest that precise documentation of total slip during slow slip events, along with refinement of viscoelastic locking models, will provide new insights into the net slip budget available in the ETS zone. This will help assess the potential of future coseismic and/or postseismic slip penetrating into the ETS zone in Nankai, Cascadia and other subduction zones. [ABSTRACT FROM AUTHOR]

To elucidate the nonlinear oscillations inherent to dielectric elastomer transducers (DETs), this study delves into the dynamic behaviour exhibited by a one-dimensional asymmetric Duffing oscillator, which may exhibit either hardening or softening stiffness. The investigation utilizes hyperelastic and visco-hyperelastic constitutive models to capture the nonlinear stiffness properties of dielectric elastomers within compliant transducers. The canonical Duffing equation is employed to articulate the oscillator's motion, complemented by both asymptotic and quantitative analyses of unforced vibrations and harmonic excitation. Our results reveal that the distinctive stiffness characteristics observed in DETs arise from the complex interplay among hyperelasticity, rheology and applied electric fields. Contrary to conventional oscillators, Maxwell stress substantially modifies the nonlinear dynamics of DETs, an aspect that has been quantitatively dissected in this study. Furthermore, the influence of additional system parameters on forced oscillation has also been meticulously evaluated. [ABSTRACT FROM AUTHOR]

The investigation results of granulometric composition, zeta potential, sedimentation stability, and viscosity of some water-coal suspensions made of Ukrainian coal from the “Stepova” mine, Lviv-Volyn region, are reported. The most effective granulometric composition of the water-coal suspension consisting of the rough and fine fractions is found from the analysis of the abovementioned physicochemical characteristics of the suspensions. Based on the complex investigation of the zeta potential of the dispersed phase particles, viscosity, and sedimentation stability of the suspensions, it was established that the best technological effectiveness can be expected for the suspensions containing 60% of the rough fraction (sized between 100 and 250 µm) and fine particles sized between 20 and 40 µm. In such systems, the particles form a quasi-stable structure, where the lower-charged small particles are located in the interparticle space between the highly charged bigger particles. All particles bear the same charge, increasing the system’s sedimentation stability and avoiding decomposition for at least 5 days. This time seems reasonable for the preparation, storage, and pumping of the suspensions while their viscosity and stability meet the relevant technological requirements. [ABSTRACT FROM AUTHOR]

In this paper, we study the uniqueness of the steady 1-D shock solutions for the inviscid compressible Euler system in a finite nozzle via asymptotic analysis for physical parameters. The parameters for the heat conductivity and the temperature-depending viscosity are investigated for both barotropic gases and polytropic gases. It finally turns out that the hypotheses on the physical effects have significant influences on the asymptotic behaviors as the parameters vanish. In particular, the positions of the shock front for the limit shock solution (if exists) are different for different hypotheses. Hence, it seems impossible to figure out a criterion selecting the unique shock solution within the framework of the inviscid Euler flows. [ABSTRACT FROM AUTHOR]

Eddy viscosity is employed throughout the majority of numerical fluid dynamical models, and has been the subject of a vigorous body of research spanning a variety of disciplines. It has long been recognized that the proper description of eddy viscosity uses tensor mathematics, but in practice it is almost always employed as a scalar due to uncertainty about how to constrain the extra degrees of freedom and physical properties of its tensorial form. This manuscript borrows techniques from outside the realm of geophysical fluid dynamics to consider the eddy viscosity tensor using its eigenvalues and eigenvectors, establishing a new framework by which tensorial eddy viscosity can be tested. This is made possible by a careful analysis of an operation called tensor unrolling, which casts the eigenvalue problem for a fourth‐order tensor into a more familiar matrix‐vector form, whereby it becomes far easier to understand and manipulate. New constraints are established for the eddy viscosity coefficients that are guaranteed to result in energy dissipation, backscatter, or a combination of both. Finally, a testing protocol is developed by which tensorial eddy viscosity can be systematically evaluated across a wide range of fluid regimes. Plain Language Summary: Numerical fluid flow solvers need to dissipate energy in order to remain numerically stable, and this is most often achieved by adding a mechanism to the governing equations called eddy viscosity. Generally the implementation of eddy viscosity boils down to specifying a scalar coefficient that governs the rate of energy dissipation. However, the true mathematical form of eddy viscosity is that of a higher‐order geometric object called a tensor, and the potential advantages of using this form remain unexplored. This paper uses a generalized version of familiar linear algebra operations (eigenvalues, trace, and determinant) to establish new constraints on the eddy viscosity coefficients that promise to open up this parameterization to renewed scrutiny. Key Points: Eddy viscosity is usually employed as a scalar coefficient, but its true form is that of a tensorEigenanalysis can reveal new constraints on the coefficients of the eddy viscosity tensorTensor unrolling can help expose the power of the eigenanalysis, but only if done in a particular way [ABSTRACT FROM AUTHOR]

The theory and application of the vibrating-wire technique for the measurement of viscosity, as well as both viscosity and density, are reviewed. Theory is presented in the form of practical working equations and well-established limitations on their ranges of validity. The cases of both transient and steady-state excitation of the vibrating wire are considered in detail. For the steady-state mode, we describe a variant of the method in which the density is also measured. Practical details including wire materials, magnet systems and instrumentation are discussed, and several design examples from the literature are reviewed. Relative uncertainties in vibrating-wire viscometry vary from, at best, 0.2 % to about 2 % at 95 % confidence. In an appropriately designed instrument, density can be measured simultaneously with a relative uncertainty of about 0.2 %. [ABSTRACT FROM AUTHOR]

Viscosity is a thermophysical property of paramount importance, being essential for many scientific and industrial applications. The most common instruments for its measurement are glass capillary viscometers. Therefore, the use of capillary viscometers is widespread both in industry and in research. The range of viscosities of interest range from lower than that of water to several orders of magnitude higher values, the measurement of which requires different capillary viscometers. Most of the practical applications concern routine instruments, mainly for quality control. One main issue for the utilization of capillary viscometers relates to the need for their calibration, assuring its traceability to the water primary viscosity standard, to certify its worldwide validity. The present paper focuses on capillary instruments dedicated to perform viscosity measurements on Newtonian organic liquids at atmospheric pressure, as it is assumed that is the most widespread type of application for these viscometers. Capillary viscometry has a completely well-defined working equation, namely, the Hagen–Poiseuille equation. However, the practical performance of the measuring instruments deviates from that working equation. Most of those deviations are currently considered by many users. However, some of those deviations have not reached that status yet, like those concerning the effects due to the surface tension of the sample on the measurements. All these aspects are summarized and analyzed in the present article, together with a brief general description of the most common types of capillary viscometers, namely, the Ostwald and the constant-level or Ubbelohde instruments. [ABSTRACT FROM AUTHOR]

Alternative sources for an industrial production of essential substances represent an exciting field of study for many researchers. Based on the previous research, itaconic acid and its esters were intensively studied as one of the sources. This paper relates to a determination of the basic physical–chemical properties of bis(2-methylbutyl) itaconate and bis(3-methylbutyl) itaconate that are produced from itaconic acid and 2-methylbutan-1-ol and 3-methylbutan-1-ol, respectively, from biomass. According to our best knowledge, physical–chemical properties of these substances, such as density, viscosity, and saturated vapor pressure, are not presented in the literature, and these are important for the future research of their production. [ABSTRACT FROM AUTHOR]

Understanding of thermophysical and transport properties of H2-NG blends are needed for the gradual introduction of hydrogen into the national gas grid. A capillary tube viscometer was used to measure the viscosity of hydrogen + methane blends (with hydrogen mole fraction = 0, 0.1000, 0.1997, 0.5019, and 1) at temperatures from 213 to 324 K and pressures up to 31 MPa. A total 147 experimental viscosity measurements were made for the three H2 + CH4 blends and compared against the predictions of five different viscosity models: a one-reference corresponding states (Pedersen) model, a two-reference corresponding states (CS2) model, an extended corresponding states (ECS) model, a corresponding states model derived from molecular dynamic simulations of Lennard Jones (LJ) fluids, and a residual entropy scaling (SRES) method. All the model predictions showed a relatively low deviation compared to the measured viscosities. The density required for viscosity model predictions were computed using Multi-Fluid Helmholtz Energy Approximation (MFHEA) equations of state (EoS). To check the experimental procedure and applicability of the viscometer equipment, viscosity validation measurements were carried out for propane, hydrogen, and methane. The measured viscosities of the pure components were in good agreement with the respective viscosity models with AARD of 0.24%, 0.25%, and 0.58% for propane, hydrogen, and methane, respectively. [ABSTRACT FROM AUTHOR]

The publication presents the functions of the SLAG software created to recreate historical metallurgical processes. SLAG allows for determining the smelting temperature, the viscosity of the metallurgical melt, and the oxygen and sulfur fugacities during smelting. With software, both liquidus temperature and melt viscosity can be calculated using different models, covering the range of chemical compositions of historical slags as wide as possible. Based on thermodynamic calculations, SLAG allows the performance of O2 and S2 fugacity calculations in the temperature range of 1000–2000 K (727–1727°C). The range of applicability of other properties (viscosity and liquidus temperature) depends only on the limitations of individual models. Using SLAG, it is also possible to create predominance area diagrams (PADs) and diagrams that consider the viscosity's dependence on temperature for slag of a given chemical composition. Based on glass transition temperature (Tg) and melt fragility, it is also possible to reconstruct the conditions that prevailed during the various stages of historical glass manufacturing processes. [ABSTRACT FROM AUTHOR]