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Field and remote sensing studies suggest that ice mélange influences glacier-fjord systems by exerting stresses on glacier termini and releasing large amounts of freshwater into fjords. The broader impacts of ice mélange over long time scales are unknown, in part due to a lack of suitable ice mélange flow models. Previous efforts have included modifying existing viscous ice shelf models, despite the fact that ice mélange is fundamentally a granular material, and running computationally expensive discrete element simulations. Here, we draw on laboratory studies of granular materials, which exhibit viscous flow when stresses greatly exceed the yield point, plug flow when the stresses approach the yield point, and stress transfer via force chains. By implementing the nonlocal granular fluidity rheology into a depth- and width-integrated stress balance equation, we produce a numerical model of ice mélange flow that is consistent with our understanding of well-packed granular materials and that is suitable for long time-scale simulations. For parallel-sided fjords, the model exhibits two possible steady state solutions. When there is no calving of new icebergs or melting of previously calved icebergs, the ice mélange is pushed down fjord by the advancing glacier terminus, the velocity is constant along the length of the fjord, and the thickness profile is exponential. When calving and melting are included, the ice mélange evolves to another steady state in which its location is fixed relative to the fjord walls, the thickness profile is relatively steep, and the flow is extensional. For the latter case, the model predicts that the steady-state ice mélange buttressing force depends on the surface and basal melt rates through an inverse power law relationship, decays roughly exponentially with both fjord width and gradient in fjord width, and increases with the iceberg calving flux. The increase in buttressing force with the calving flux, which depends on glacier thickness, appears to occur more rapidly than the force required to prevent the capsize of full-glacier-thickness icebergs, suggesting that glaciers with high calving fluxes may be more strongly influenced by ice mélange than those with small fluxes. [ABSTRACT FROM AUTHOR]

Entropy generation with activation energy has garnered worldwide attention from researchers due to its extensive applications in thermodynamic design, chemical engineering, and optimization processes. One of the primary reasons for focusing on entropy is the global energy crisis, driven by massive consumption against limited resources. This study elucidates the double diffusion process in the dynamics of a viscous fluid over a stretching cylinder, incorporating considerations of entropy generation and activation energy. The non‐Fourier heat flux model is employed to describe the thermodynamics of the thermal system, while non‐Fick's law is used to elucidate the mass diffusion process. The unsteady phases of axisymmetric flow of the viscous fluid are thoroughly discussed. Transport equations in cylindrical configuration are transformed into ordinary differential equations, and an efficient mathematical method (i.e., homotopy analysis method) is applied to solve the transformed system. The graphical examination reveals the impact of flow parameters on velocity configuration, entropy configuration, temperature configurations, and concentration configurations. Additionally, a comparative benchmark is established with the results from previously published work for authentication and validation purposes. It is noted that concentration and temperature configurations are directly related to the unsteady stretching parameter. Entropy generation exhibits an inverse relationship with the unsteady stretching parameter when close to the stretching cylinder, whereas it shows a direct relationship when the fluid is flowing away from the surface. [ABSTRACT FROM AUTHOR]

We have generalized, in the current study, the results of research presented earlier with the aim of obtaining an approximate solution for the creeping, plane-parallel flow of viscoplastic non-Newtonian fluid where the focus is on the study of rivulet fluid flows on an inclined surface. Namely, profiles of velocity of flow have been considered to be given in the same form as previously (i.e., Gaussian-like, non-stationary solutions) but with a novel type of pressure field p. The latter has been chosen for solutions correlated explicitly with the critical maximal non-zero level of stress τs in the shared plane layer of rivulet flow, when it begins to move as viscous flow (therefore, we have considered here the purely non-Newtonian case of viscoplastic flow). Correlating phenomena such as the above stem from the equations of motion of viscoplastic non-Newtonian fluid considered along with the continuity equation. We have obtained a governing sub-system of two partial differential equations of the first order for two functions, p and τs. As a result, a set of new semi-analytical solutions are presented and graphically plotted. [ABSTRACT FROM AUTHOR]

The current study emphasizes bioconvective viscous fluid flow between two horizontal deformable cylinders. At the cylindrical walls, the Newtonian heat and mass condition with velocity slip is examined. The thermal and solutal transfer is optimized by amalgamating Soret–Dufour effects with variable heat source/sink. The equations that regulate the flow are simplified via appropriate transformations. The bvp4c algorithm is employed to obtain the numerical solution. The ramifications of the emerging parameters are portrayed graphically. Numerical values for drag force coefficient, heat flux, mass flux, and local motile density numbers are enumerated in tabulated form. Axial velocity accelerates on varying the unsteadiness parameter. The thermal field elevates by augmenting the Dufour number and thermal conjugate parameter. The drag force coefficient exhibits a decreasing behavior on enhancing the unsteadiness and velocity slip parameters. An opposite behavior is exhibited by heat and mass flux on amplifying the Soret and Dufour number. Motile density deteriorates on elevating the Lewis number and unsteadiness parameter. A substantial correlation has been noticed by graphically comparing the results of this study with the previous literature. [ABSTRACT FROM AUTHOR]

The rapid advancement in aeronautics has led to the emergence of intricate dynamic processes and structures, such as vortices, shock waves, flow separation, and turbulence, resulting from the flow around airfoils. Acquiring a profound understanding of these local structures and unraveling the physical mechanisms underlying flow phenomena represents an essential and challenging issue in the field of flight science. In this research, the longitudinal–transverse force theory (L–T force theory), as proposed by previous researchers, is employed to quantitatively assess contributions of local flow structures to aerodynamic forces. Specifically, the research encompasses an analysis of steady and viscous compressible flow over the Royal Aircraft Establishment (RAE)-2822 airfoil, with free-stream Mach number ( M ∞ ) ranging from 0.1 to 2.0. We comprehensively estimate longitudinal forces (L-force) and transverse forces (T-force), along with effects of compressibility on aerodynamic forces. Furthermore, recognizing the necessity for high-precision algorithms in the computation of L–T force theory, this investigation utilizes a sixth-order accuracy algorithm for spatial discretization and differencing. Our analysis reveals that the influence of compressibility and the contributions of L-forces to aerodynamic forces become increasingly significant in high M ∞ regimes as shearing processes weaken. Additionally, a new similarity law is established to characterize aerodynamic forces acting on the RAE-2822 airfoil based on a novel moderating factor, ζmo, reduced from local Mach factors in the L–T force theory. This coefficient, ζmo, elucidates the degree to which transverse processes are modulated by longitudinal processes. Various angles of attack α and airfoils have also been analyzed, including National Advisory Committee for Aeronautics (NACA)0012 and NACA0006, by introducing a parameter denoted as κ to further validate the universality of the new similarity laws. The results demonstrate a high degree of accuracy in fitting the aerodynamic coefficients. [ABSTRACT FROM AUTHOR]

A metal/liquid-metal junction is a practical thermoelectric cell causing heat absorption or release according to the direction of electric current and temperature gradient. During thermoelectric processes, the possibility of activating the anomalous heat transfer is considered in this work based on adopting a fractional version of Jeffreys equation with three fractional parameters. Because of the connection between the mean-squared displacement of diffusive hot particles and the thermal conductivity, the fractional Jeffreys law is employed to simulate the low thermal conductivity with crossovers; accelerated or retarded transition, and the transition from high (superconductivity—above the Fourier heat conduction) to low (subconductivity—below the Fourier heat conduction) thermal conductivity. The Couette formulation describing a pressure-driven flow of a viscous thick liquid-metal layer bounded by two similar metallic plates, in the presence of a constant transverse magnetic field, is investigated. A triple-phase pressure gradient, consisting of the phases: (i) ramp-up, (ii) dwell, and (iii) exponential decay, is applied as a real-life flow cause and compared with the classical constant pressure gradient and the impulsive pressure gradient case. The velocity and temperature are obtained in the Laplace domain, and then a suitable numerical technique based on the Fourier series approximation is used to recover the solutions in the real domain. It is found that the retarded crossover of low thermal conduction shows "ultraslow" temperature propagation within the thick layer, which indicates to a case of ultralow heat conduction. As well as the strong correlation between the pressure gradient type (constant, impulsive, or three-phase) and direction (favorable or adverse) and its induced velocity, the temperature gradient between the two plates plays a key role in the determination of the velocity direction and magnitude. [ABSTRACT FROM AUTHOR]

Understanding the evolution of water droplets moving in a highly viscous bulk flow (e.g., bitumen) has attracted increasing attention in the context of numerous separation technologies due to various issues relating to the environment (re-use of water) and engineering failures (corrosion of pipelines). With this in mind, the main objectives of this work are to explore the dynamics of water droplets with a diameter of seven micrometers, moving in highly viscous bitumen flowing through a smoothly converging and diverging 11-micron channel using three-dimensional (3D) and two-dimensional (2D) droplet-resolved simulations and to adjust an existing population balance model (PBM) to predict geometry-driven coalescence for different flow rates. The Eulerian–Eulerian (EE) method coupled with a new PBM is used to predict the behavior of water droplets with a diameter of 7 μm. Numerical simulations were carried out for various capillary numbers (0.1 < C a < 3) and compared with the volume of fluid method combined with the level-set function (CLSVOF). Adaptive mesh refinement (up to six levels) was used in 3D and 2D CLSVOF simulations, producing interface cells measuring up to 30 nm. Good agreement was observed between EE-PBM and CLSVOF models. For comparison, we show the results of 2D CLSVOF simulations. This new PBM model can be used to predict water–oil separation in new cascade-formed geometries to enhance the coalescence of water droplets in highly viscous bulk flows. [ABSTRACT FROM AUTHOR]

In this study, a fluid flow with an incompressible axisymmetric steady couple stress translated through a porous media is analyzed between a hollow sphere and a concentric rigid sphere. In the permeable region, the flow field is regulated by Brinkman's equation. The slip and spin slip conditions are applied on both the rigid sphere and spherical cavity surfaces. Modified Bessel functions provide a systematic approach to the problem by utilizing the principle of a stream function. On the inner sphere, the wall correction factor that an incompressible couple stress fluid encounters is calculated. The effects of the slip, spin slip, coupling stress parameter, separation distance, and permeability parameter on the field functions and the normalized drag force are also graphically shown. The corresponding results are contrasted with the outcomes reported for particular cases of couple stress fluid and viscous fluid flow in two permeability-free concentric circles. Furthermore, graphs of the streamlines for various values of the relevant parameters have been included. [ABSTRACT FROM AUTHOR]

This study intends to investigate the hybrid nanofluids with viscous dissipation and thermal radiation effects of the magnetic field. The consequences of viscous dissipation and thermal radiation on the transport of Cu - Ti02/water and CUO - Ti02/water were investigated. Magnetic fields create a hybrid nanofluid with varying viscosity. By including suitable symmetry variables, the fluid model is converted into ordinary differential equations. For the numerical simulation, we employ the bvp4c package in MATLAB. The evaluation's findings are laid out graphically in tables and charts. Various values of crucial parameters such as variable viscosity, magnetic field, viscous dissipation. and nanoparticle volume fraction are investigated better to grasp the nature of the problem's energy flow and energy transfer characteristics. It was revealed that raising the magnetic field and the suction/injection parameters reduces velocity. While the fluid velocity remains constant, the temperature distribution changes as the viscous dissipation, magnetic field, and thermal radiation parameters increase. [ABSTRACT FROM AUTHOR]

Study of some physicochemical properties of l-aspartic aid in water and aqueous ammonium acetate has been undertaken for this investigation. Density, viscosity and conductivity of the solutions were measured at different temperatures. Volumetric parameters such as apparent molar volume (V Φ) , partial molar volume (V Φ 0) , partial molar expansibility (E Φ 0) and Hepler's constant ( ∂ 2 V Φ 0 / ∂ T 2) p) and viscometric parameters such as relative viscosity (η r) , viscosity coefficients (B J and A F) , Gibbs free energy of activation of viscous flow of solvent and solute (Δ μ 1 # , 0 and Δ μ 2 # , 0 ) respectively) and corresponding change in enthalpy Δ H 2 # , 0 and entropy Δ S 2 # , 0 have been derived from the experimentally measured density and viscosity values. Variation of these parameters with concentration and temperature was analysed in the light of ion–ion and ion–hydrophilic interactions. The possibility of ion pair formation and its effect on migration of charged particles in solution have been determined by analysing the molar conductance (Λm), association constant (K A) , Walden product and thermodynamic functions. These parameters were qualitatively correlated with changes in structure of water that occurs when l-Aspartic acid interacts with ammonium acetate in aqueous media. [ABSTRACT FROM AUTHOR]

Most of the oil transportation industries deal with liquid-liquid flow considering the adiabatic situation. In such applications, film thickness measurement plays a very significant role in understanding the flow characteristics. The distribution of phases for efficient wall treatment and to understand the phase distribution, measurement of film thickness is very important. Among different flow patterns, stratified flow is most common for low and medium viscous oil-water flow. At lower oil velocities, stratified flow is observed downstream of singularity whereas in the upstream section, stratified flow is observed for low to medium oil velocities and high-water superficial velocity. Variation of oil film thickness for stratified flow has been analyzed in this study. Results show that oil film thickness decreases with the increase in the superficial velocity of water (Us-Water) for a constant oil superficial velocity (Us-Oil). With the increase in the volume fraction of one phase, the film thickness of that phase increases. As Us-Oil increases, the film thickness of oil also increases for a constant Us-Water. Oil film thickness is directly proportional to the viscosity of oils. This means, the more the viscosity of the oil, the more will be the oil film thickness. [ABSTRACT FROM AUTHOR]

In this article, neural network backpropagation (NNBP) is used to present two‐dimensional Darcy‐Forchheimer viscous fluid (DFVF) of viscous liquid against a stretching sheet under the influence of heat sink/source and viscous dissipation. Mathematical modelling and numerical simulation are also discussed. Thermal polymer processing, engineering processes, and industrial processes all benefit from the dynamic entropy generation phenomenon. Scientists are primarily interested in finding ways to decrease entropy formation to polish up the thermal performance of industrial systems. In this continuation, the optimal frame for the Darcy‐Forchheimer flow with a curved surface has been developed. Non‐linear partial systems are converted to dimensionless differential systems through the employment of the appropriate variables. Utilizing tools from the bvp4c method, the problem's highly nonlinear equations are numerically solved. These ODEs are solved by applying the bvp4c solution approach to produce the reference dataset for NNBP. Using this reference dataset in MATLAB, the graphs for the solution and error analysis for changing various parameters are analyzed. The performance of NNBP is validated using mean squared error data, regression analysis, and error histogram. The DFVF solution is examined using the testing, validation, and training procedures. Examined through influential variables the effects of fluid flow, thermal field, Bejan number, and concentration. [ABSTRACT FROM AUTHOR]

This paper addresses the often overlooked, yet critical, aspect of designing and optimizing the surface pipeline network for the transportation of geothermal fluids from the wellheads to the delivery point, such as greenhouses, food drying plants, or fish farming units. While research on the geothermal industry predominately focuses on the reservoir and well engineering aspects of exploitation, insufficient attention has been given to the design of the pipeline network, leading to improper design and significant, yet avoidable, energy losses. Thus, this paper presents a comprehensive methodology for modeling and simulating geothermal fluid flow within the pipeline network by fully considering all hydraulic (friction, viscous flow, and gravity effects) and thermal (open air and underground pipeline heat loss) phenomena. These two aspects are handled simultaneously by setting up and solving the coupled set of the governing (differential) equations. We also demonstrate the difficulties that arise when attempting the solution of the mathematical problem, such as potential instability or lack of convergence. Finally, a fully detailed study of the real-world geothermal production system is presented utilizing the developed methodology to optimize the design and operation conditions of the system. By integrating debottlenecking strategies into the analysis, this approach not only maximizes power output, but also identifies and mitigates constraints within the system, ensuring efficient operation and performance increase. [ABSTRACT FROM AUTHOR]

A less prominent N-S oriented continental-scale strike-slip shear zone occurs within the Babouri-Figuil Magmatic Complex (BFMC). Studies have shown that such shallow to middle crustal levels shear zones often display long-lasting deformation, physical expression of strain localization, and mineralization. However, until dates, deformation evolution and structural mineralization of this ~ 8 km long shear zone in Babouri-Figuil remain enigmatic, which prompted its investigation. A combined structural study supported by U-Pb zircon dating on the sheared granitoids is reported. Biotite granite sampled near Sorawel village yielded zircon U-Pb concordia age of 606 ± 6 Ma, whereas hornblende-biotite granite sampled at the western corner of the Ribao massif yielded zircon U-Pb concordia age of 601 ± 2 Ma. These granites were emplaced in a transpressive tectonic regime shortly after a regional thickening event < 620 Ma. The studied microstructures demonstrate a typical transition from protomylonite to extremely deformed mylonite marked with decreased mineral sizes. On thin sections, two main zones are identified: "zone A" (low-strain zone) and "zone B" (high-strain zone). Core-mantle K-feldspar porphyroclasts within the mylonite show dislocation creep deformation, whereas recrystallized to neocrystallized aggregates indicate plastic flow by viscous grain boundary sliding. Shear sense indicators revealed both early dextral and late sinistral shearing. In all, the results revealed that the Guider-Sorawel shear zone (GSSZ) experienced ductile deformation probably under medium to high temperature conditions. The double shearing is possible during the switch of the regional maximum principal stress from N-S (~ 585 Ma) to NW-SE (< 580 Ma). The obtained dates are syn-collisional and are consistent with D2 deformation phase in other parts of Cameroon. Also, the dates marked the final tectonic college between the north Cameroon domain and the southwest Chad domain, which probably might have induced the SZ. The construction of these adjacent domains probably resulted to a sort of increased temperature and strain localization that led to the initiation of a rheologically weaken mechanical zone via which the magma generated flows to near surface crustal level. [ABSTRACT FROM AUTHOR]

This article presents the numerical investigation of magnetohydrodynamic (MHD) heat transfer flow of viscous dissipation in vertical channel in the presence of Newtonian heating. The coupled nonlinear dimensional partial differential equations governing the flow are converted into non-dimensional form by using the appropriate dimensionless quantities and parameters Implicit Finite Difference Method (IFMD) was employed in finding the solutions of dimensionless partial differential equations. The expressions of velocity, temperature, skin friction and Nusselt number were obtained numerically and discussed using line graphs. From the outcome of the results, it was concluded that rising the Newtonian heating parameter (γ), Brinkman number (Br), lead to a substantial growth of velocity and temperature. Similarly, as the, Grashof number (Gr) increases, the velocity of the fluid also gets increased. The skin friction gets enlarged with the increase of Grashof number (Gr), Newtonian heating parameter (γ), Brinkman number (Br) and time at y = 0 and y = 1. The Nusselt number gets reduced with the increase in Newtonian heating parameter (γ), Brinkman number, and time parameter at y = 0 and increases at y = 1. [ABSTRACT FROM AUTHOR]

Shape‐morphing structures capable of significantly altering shape and volume play a crucial role in diverse applications, ranging from soft robotics to minimally invasive surgery, deployable structures, and space exploration. This article presents an approach to achieve simple and controllable morphing onto multiple stable complex 3D surfaces—a long sought after goal in the field. The method is based on interconnected multistable straw‐like deformable tubes, constrained by rigid links that can be assembled and connected in many different ways. By leveraging the director‐field theory, the links and their assembly process are modeled and designed to reach a variety of desired final operational shapes from a single base‐structure. The use of viscous‐fluid actuation enables precise control and predictable shape‐morphing while facilitating a wide range of configurations through inflation and deflation sequences, all with a single input.

We report on progress in observing the hydrogen-bonded structure of water and sea water by deep-ocean Raman spectroscopy. In the normal ocean, the abundance of single H2O species is less than 20%. The principal form is the tetrahedral pentamer, and the (H2O)[Formula: see text] nH2O equilibrium plays a dominant role in controlling physicochemical processes and the speed of sound. The enthalpy of the H-bond in water is 2.624 kcal/mol, and in sea water 2.258 kcal/mol due to the quantity of non-HB water in the solvation shell of sea salt ions. The activation energy of viscous flow is 4.28 kcal/mol at one atmosphere pressure, consistent with the need to break hydrogen bonds and overcome the van der Waals intermolecular forces. The activation energy decreases exponentially with depth/pressure and is 10% less at 4,000 m depth. We suggest this is due to the pressure-induced shift in the water equilibrium to favor the less compressible quasi-planar pentamer, tetramer, and so on forms. We address the long-standing conclusion that microbial swimming by means of rotating flagella is only 1%–2% efficient. This neglects the need for microbes to overcome the activation energy of viscous flow; [Formula: see text]95% of the mechanical energy produced by the flagella must be used to break H-bonds and overcome intermolecular forces.

In the current study, the influence of different BaO/Al 2 O 3 ratios and Li 2 O contents on the viscosity, melting temperature, crystallization behavior and structure of BaO–Al 2 O 3 –TiO 2 -based mold slags was investigated through the measurement of the viscosity-temperature relationship, hemisphere point method, crystallization process and crystallization temperature, and the calculation of NBO/T and optical basicity. With the increase of the BaO/Al 2 O 3 ratio from 0.60 to 1.67, the viscosity at 1573 K and the melting temperature of mold slags decreased from 0.3 to 0.05 Pa s, and 1261 K–1217 K, respectively, while those also slightly decreased from 0.15 Pa s to 0.11 Pa s, and 1244 K–1213 K with the Li 2 O content from 4 % to 6 %, respectively, which was related to the increase of fluxing reagent or oxygen ions released by basic oxide in slags. In current slags, precipitated phases mainly existed as LiTiO 2 and BaTiO 3 , and the difference of the BaO/Al 2 O 3 ratio and Li 2 O content resulted in the competitive precipitation of these phases. With the increase of BaO/Al 2 O 3 ratio from 0.60 to 1.67, precipitated phases gradually changed from LiTiO 2 to BaTiO 3 , and the initial crystallization temperature had the tendency to decrease and increase. On the contrary, the precipitated phase gradually changed from BaTiO 3 to LiTiO 2 , and the initial crystallization temperature as well as the break temperature decreased with the Li 2 O from 4 % to 8 %. The parameter NBO/T and optical basicity of molten slags increased with the increase of BaO/Al 2 O 3 and Li 2 O content, and the polymerization degree of the melt decreased, resulting in the decrease of the activation energy of viscous flow and the viscosity. Hence, the increase of the BaO/Al 2 O 3 ratio and Li 2 O content within limits could lower the viscosity, melting temperature, break temperature and crystallization ability of mold slags, and then improve the lubrication of the slag on solidified shell. [ABSTRACT FROM AUTHOR]

Variational autoencoder architectures have the potential to develop reduced-order models for chaotic fluid flows. We propose a method for learning compact and near-orthogonal reduced-order models using a combination of a β-variational autoencoder and a transformer, tested on numerical data from a two-dimensional viscous flow in both periodic and chaotic regimes. The β-variational autoencoder is trained to learn a compact latent representation of the flow velocity, and the transformer is trained to predict the temporal dynamics in latent-space. Using the β-variational autoencoder to learn disentangled representations in latent-space, we obtain a more interpretable flow model with features that resemble those observed in the proper orthogonal decomposition, but with a more efficient representation. Using Poincaré maps, the results show that our method can capture the underlying dynamics of the flow outperforming other prediction models. The proposed method has potential applications in other fields such as weather forecasting, structural dynamics or biomedical engineering. Reduced-order models provide better understanding for complex spatio-temporal dynamics of fluid flows with high numbers of degrees of freedom and non-linear interactions. The authors propose a variational autoencoder and transformer framework for learning the temporal dynamics of the nonlinear reduced-order models relevant for fluid dynamics, weather forecasting, and biomedical engineering. [ABSTRACT FROM AUTHOR]

The paper analyzes the excess free volume relaxation mechanism of the phase transformation, which is realized in the local dilatation region at the phase interface between the crystal and the melt. It also examines the structural state of phase interface and its influence on the phase interface mobility under pressure, applied during crystal growth from the melt. The paper explains the extreme impact of pressure on the mobility of phase interface. It also discusses the possibility of the phase interface reaching a state of anomalously high mobility under "optimal" pressure (referred to as "ultra-mobility"). As part of the mechanism of viscous flow of melt into the local dilatation region at the phase interface, arising in the crystallization process, a quantitative agreement with the experimental value of the "optimal" pressure, which ensures the extreme nature of the crystal–melt phase interface mobility, has been obtained. [ABSTRACT FROM AUTHOR]

While glacial remnants in the form of viscous flow features in the mid-latitudes of Mars are considered to be cold-based in the present-day, an increasing amount of geomorphic evidence suggests that at least some flow features were previously wet-based or had a mixed thermal state (polythermal) at during their evolution. Many of the viscous flow features known as glacier-like forms have been observed to emerge from alcoves that appear similar to cirques on Earth. Terrestrial cirques are typically characterized by a concave basin connected to a steep backwall. Cirques are expected to form from depressions in mountainsides that fill with snow/ice and over time support active glaciers that deepen the depressions by wet-based glacial erosion. To assess which alcoves on Mars are most "cirque-like", we mapped a population of ~2000 alcoves in Deuteronilus Mensae, a region in the mid-latitudes of Mars characterized by mesas encompassed by glacial remnants. Based on visual characteristics and morphometrics, we refined our dataset to 386 "cirque-like alcoves", which is five times the amount of glacier-like forms in the region, and used this to assess the past extent and style of glaciation on Mars. Using high resolution imagery, we find geomorphic evidence for glacial occupation associated with the cirque-like alcoves, including crevasse-like features, surface lineations, polygonal terrain, and moraine-like ridges. We propose that the cirque-like alcoves with icy remnants similar to rock glaciers on Earth represent a late stage of glacier-like form evolution. We also outline stages of cirque-like alcove evolution, linking a potential early stage of cirque-like alcoves to gully activity. On a population-wide scale, the cirque-like alcoves have a south to southeastward aspect bias, which may indicate a requirement for increased insolation for melting to occur and a connection to gullies on Mars. While the alcoves also have similarities to other features such as landslide scarps and amphitheater-headed valleys, the cirque-like alcoves have unique morphologies and morphometrics that differentiate their origin. Assuming warm-based erosion rates, the cirque-like alcoves have timescales consistent with both glacier-like forms and other viscous flow features like lobate debris aprons, whereas cold-based erosion rates would only allow the older timescales of lobate debris aprons. We propose that based on the geomorphic features and southward aspect, cirque-like alcove formation is more consistent with warm-based glaciation. [ABSTRACT FROM AUTHOR]

Micro-nozzles play a critical role in various applications, such as micro-/nano-satellites in aerospace and heat dissipation and cooling in microelectronic systems (MEMS). The flows inside micro-nozzles can experience both continuum and rarefied flow due to their small size. In this research, we explore the optimal geometry configuration of micro-nozzles to achieve comprehensive performance and size, as well as background pressure compensation. Using classical computational fluid dynamics (CFD) and direct simulation Monte Carlo methods (DSMC), we investigate the effects of the expansion ratio, cross-profile shape, and plug on the performance of micro-nozzles operating over a wide range of pressures (0. 5 − 100 kPa). The results reveal that micro-nozzle performance is influenced by the interplay between flow expansion and viscous loss induced by the subsonic layer next to the micro-nozzle wall. The findings show that micro-nozzle performance improves with increasing expansion ratio in slip and continuum flow regimes, but decreases in the transition flow regime. Additionally, the results indicate that the axisymmetric micro-nozzle (with a circular cross-profile) outperforms the linear micro-nozzle (with a rectangular cross-profile) in terms of both performance and size when subject to the same conditions, making it the recommended choice for practical applications. We also find that plugs designed at the throat decrease performance, but increase stability under diverse background pressures. This study provides valuable insights for the design of high-efficiency micro-nozzles in applications such as nanosats and MEMS heat dissipation units. • Geometry configuration effects on micro-nozzle performance are studied numerically. • Viscous loss and flow expansion degree are pivotal for micro-nozzle performance. • Low expansion ratio micro-nozzle is better for comprehensive performance and size. • The axisymmetric micro-nozzle surpasses the linear micro-nozzle. • The plug micro-nozzle performs well in variable pressure ambient. [ABSTRACT FROM AUTHOR]

Slit-type barriers serve as active countermeasures against debris flow. However, the dynamic interaction between debris flows and slit-type barriers is extremely complicated. To model the fluid-solid behavior of debris flows, a coupled approach of smoothed particle hydrodynamics (SPH) and discrete element method (DEM) is developed. We use the model to investigate the dynamics of how debris flows impact slit-type barriers. The proposed approach is able to simulate the embedding of arbitrarily shaped particles in viscous debris flows. A GPU acceleration technique is employed to overcome large computational costs. The approach is first validated by comparing numerical results to experimental observations for some standard conditions. Subsequently, experiments of the impact of water-enriched debris on slit-type barriers are modeled and validated. Moreover, the effects of barrier arrangement, solid volume fraction and boulder shape on debris-barrier interactions are further explored. This study analyzes the interaction between debris flows and slit-type barriers by coupled SPH–DEM and provides insight into the optimal design of barriers. [ABSTRACT FROM AUTHOR]

According to a remarkable result, the polarization diffusion coefficient of drugs, such as those that slow down and ease the body, may be determined based on the rise in magnetism that follows. This research examines how a magnetic field impacts the Casson-type flow of a viscous, incompressible hybrid nanofluid that naturally flows across two parallel plates. Copper (Cu) and aluminum-oxide (Al2O 3) are the two nanoparticles and their physical properties are intended to be the foundation fluids, together with water and sodium alginate as based fluids. The revised fractional model is investigated using the Laplace transformation using the most current and updated definition of the fractional-order derivative with memory effect, i.e. Prabhakar fractional derivative. The impacts of various constraints on distinct nanoparticles are investigated and visually depicted. As a result, we have concluded that a drop in volumetric percentage reduces fluid velocity. The water-based hybrid nanofluid (HNF) has a more significant influence on the temperature and momentum profile than the sodium alginate-based HNF due to the physical appearances of the investigated nanoparticles. The Casson fluid parameter augmentation also regulates the velocity profile by decreasing the velocity field. [ABSTRACT FROM AUTHOR]

For the first time, the locally power-law preconditioning method (LPLPM) is used to formulate the preconditioned characteristic boundary conditions (CBCs). Then, it is implemented to solve the numerical modeling of unsteady and steady flows from viscous to turbulent regimes. The compatibility equations and Riemann invariants are mathematically derived and then utilized to the incompressible flow solvers as suitable boundary conditions. This method discretizes time derivative and governing equations' space terms by applying the four-stage, fourth-order Runge–Kutta method, and a finite volume, respectively. The preconditioning matrix in the LPLPM is automatically derived by local velocity sensors through a power-law formulation. The baseline k−ω is applied as an appropriate turbulence model. Several test cases are conducted around airfoils of Office National d'Etudes et de Recherches Aerospatiales, NACA0012 (National Advisory Committee for Aeronautics), and S809 at varied angles of attack of 0–20 and Reynolds numbers of 500 to 5.25 × 106 to examine the effectiveness and accuracy of the LPLPM employing preconditioned CBCs. A sensitivity analysis is also performed to examine how numerical parameters affect the simulation. The results show that using preconditioned CBCs in conjunction with LPLPM at the artificial boundary is precise, reliable, and computationally efficient in simulating viscous/turbulent flows. Furthermore, it is also concluded that the present approach considerably improves the convergence speed contrasted to the simplified boundary conditions. [ABSTRACT FROM AUTHOR]

Understanding the thermal properties and crystallization mechanisms are crucial upon sintering of bioactive glasses. In this study, crystallization mechanism and sintering ability of S53P4-based B12.5 borosilicate glass series, containing varying amounts of magnesium and/or strontium, was assessed. Additionally, the effect of crystallization onto these glasses bioactive properties was investigated. Glasses were composed of 47.12 SiO 2 - 6.73 B 2 O 3 - 21.77-x-y CaO - 22.65 Na 2 O - 1.72 P 2 O 5 - x MgO - y SrO, where x,y = 0, 5 or 10 (mol%). Thermal properties were analysed with DTA, and glass transition temperatures and onset of crystallization were determined to gain an overview of temperature range suitable for heat treatments, and for calculation of activation energies related to viscous flow and crystallization. Further, sintered bodies were formed by heat-treating coarse glass particles in large temperature range; their porosity was assessed, cross section were analysed by SEM and crystallinity was studied with XRD. To evaluate the impact of crystallization on the in vitro reactivity, dissolution studies were executed in SBF-solution up to one week, with pH and ion content of solution measured at the end of immersion. Immersed particles were studied with FTIR to observe changes in the glasses structure. The main crystallization mechanism of B12.5-based glasses was determined to be surface crystallization. While the crystallization interfered with viscous flow sintering of the pure borosilicate glass, Mg and Sr addition enabled sintering of amorphous bodies more easily and with wider temperature range. Mg in the composition especially enabled densification. In vitro studies presented that surprisingly, partially crystallized specimen were initially more reactive than the amorphous specimen. [ABSTRACT FROM AUTHOR]

The non-similar solution of a viscous fluid caused by a curved stretching surface with a convective boundary condition is considered in this article. The momentum equation is modified by considering the effects of MHD and mixed convection. The energy equation is modeled as subjected to joule heating and thermal radiation effects. The independent variable "s" is present in the Eckert and Grashof numbers, which is incompatible with dimensionless parameters. In this regard, a non-similar technique is used to tackle the problem. The non-similar approach has not been tried on a curved stretching surface. Moreover, the entropy rate is discussed under these observations. The non-similarity transformation is used to convert the modeled governing equations into dimensionless PDEs. A local nonsimilarity method is employed for the conversion of PDE's into ODE's, and the numerical solution of the resulting equations is obtained via bvp4c. The novelty of the problem is that when the thermal radiation, Hartman number, and Brinkman number increase, the entropy generation increases. The Bejan number increases with the Hartman number and thermal radiation, while the Brinkman number shows the opposite behavior in boundary layer. The nonlinear radiation parameter increases the thermal profile while reverse tends noticed for the entropy generation and Bejan number. The behaviors of velocity and temperature profiles are discussed graphically for the different parameters. Physical quantities like heat transfer rate and drag force are presented in tabular form. [ABSTRACT FROM AUTHOR]

In this study, we investigate the phenomenon of mixed convection in viscous fluid flow by a vertical channel, considering the presence of magneto‐hydro‐dynamics and porosity. Mixed convection occurs when both buoyancy forces and external forces, such as pumps or fans, influence the flow behavior. Understanding and accurately predicting mixed convection is crucial for optimizing heat exchanger design and performance. To model the temperature equation, we utilize the concept of the first law of thermodynamics. Additionally, we incorporate effects such as Joule heating, heat generation, and radiative heat flux in the energy equation modeling. The resulting physical liquid equations are solved using the shooting technique with the RKF (Runge–Kutta–Fehlberg) scheme. We present graphical representations of the flow variables, discussing their behavior in detail. The introduction provides an overview of the paper's roadmap, while the conclusion highlights the main and significant results obtained from our study. We found that, the temperature is more when liquid motion in between channel for large numerical values of thermal radiation parameter and Reynolds number. [ABSTRACT FROM AUTHOR]

The current study considered electromagnetohydrodynamic (EMHD) flow properties on viscid liquid over wavy walls. Initially, performed the scientific evidence and then explanation of velocity attained by applying the perturbation approach. Through mathematical calculations, we evaluated the corrugation impact on EMHD velocity flow. The impacts of evolving constraints from attained solutions are studied by intriguing the diagrams. The significant hypothesis is that decrease the imperceptible wave consequence on the velocity for the minor value of amplitude proportion parameter. For the small value of amplitude, the curvy phenomenon becomes understandable. In graphical results trapped bolus appears for out phase corrugations. From this study, we have come up with the result that the velocity achieves the extreme value in the mid of the channel. The velocity profile declines for the Reynolds number. The reason is that for the greater amount of the Reynolds number, the velocity fluctuates quickly by lesser amplitudes. The velocity profile decay with the growing value of the curving parameter in [−1,0] and grow in [0,1]. The stress components τzr±$\tau _{zr}^ \pm $ decline and the stress components τzx±$\tau _{zx}^ \pm $ rise for the curving parameter. The present analysis has practical applications in biomedical propulsion of targeted drug delivery, manufacturing of peristaltic pumps, transportation of diverse fluids. [ABSTRACT FROM AUTHOR]

In the present study, the added resistance, heave, and pitch of the KRISO Container Ship (KCS) in waves, at both model scale and full scale, are predicted numerically in regular head waves, for four wavelengths and three wave heights. The ISIS-CFD viscous flow solver, implemented in the Fidelity Fine Marine software provided by CADENCE, was employed for the numerical simulations. The spatial discretization was based on the finite volume method using an unstructured grid. The unsteady Reynolds-averaged Navier–Stokes (RANS) equations were solved numerically, with the turbulence modeled by shear stress transport (k-ω) (SST). The free-surface capturing was based on the volume-of-fluid method. The computed solutions were validated through comparisons with towing test data available in the public domain. To predict the uncertainties in the numerical solution, a systematic grid convergence study based on the Richardson extrapolation method was performed for a single wave case on three different grid resolutions. Specific attention was given to the free-surface and wake flow in the propeller plane. The purpose was to compare the numerical results from the model- and full-scale tests to examine the scale's effect on the ship's performance in regular head waves. The comparison between the model scale and full scale showed obvious differences, less accentuated for the free-surface topology and clearly observed in terms of boundary layer formation in the propeller's vicinity. [ABSTRACT FROM AUTHOR]

To address the unstable motion of a tension leg platform (TLP) for floating wind turbines in various sea conditions, an improved method of incorporating a tuned liquid multi-column damper (TLMCD) into the TLP foundation is proposed. In order to evaluate the control effect of TLMCD on the motion response of the floating foundation, a multiphase flow solver based on a viscous flow CFD method and overlapping grid technique is applied to model the coupled multi-body dynamics interaction problem involving liquid tanks, waves, and a spring mooring system. This method has been proven to accurately capture the high-frequency motions of the structure and account for complex viscous interferences affecting the geometric motions. Additionally, the volume of fluid (VOF) method and the first-order linear superposition method are used to model the focused wave, enabling a simulation of the effects of transient wave loads on the floating foundation. The results show that the tuned damping effect of TLMCD on the TLP is mainly in the pitch motion, with the maximum pitch amplitude control volume ratio of TLMCD reaching up to 86% and the maximum surge amplitude control volume ratio of TLMCD reaching up to 25.2% under the operating conditions. These findings highlight the potential for additional research on and implementation of TLMCD technology. [ABSTRACT FROM AUTHOR]

Understanding the transient properties of cementitious pastes is crucial for construction materials engineering. Computational modeling, particularly through Computational Fluid Dynamics (CFD), offers a promising avenue to enhance our understanding of these properties. However, there are several numerical uncertainties that affect the accuracy of the simulations using CFD. This study focuses on evaluating the accuracy of CFD simulations in replicating slump flow tests for cementitious pastes by determining the impact of the numerical setup on the simulation accuracy and evaluates the transient, viscosity-dependent flows for different viscous pastes. Rheological input parameters were sourced from rheometric tests and Herschel–Bulkley regression of flow curves. We assessed spatial and temporal convergence and compared two regularization methods for the rheological model. Our findings reveal that temporal and spatial refinements significantly affected the final test results. Adjustments in simulation setups effectively reduced computational errors to less than four percent compared to experimental outcomes. The Papanastasiou regularization was found to be more accurate than the bi-viscosity model. Employing a slice geometry, rather than a full three-dimensional cone mesh, led to accurate results with decreased computational costs. The analysis of transient flow properties revealed the effect of the paste viscosity on the time- and shear-dependent flow progress. The study provides an enhanced understanding of transient flow patterns in cementitious pastes and presents a refined CFD model for simulating slump flow tests. These advancements contribute to improving the accuracy and efficiency of computational analyses in the field of cement and concrete flow, offering a benchmark for prospective analysis of transient flow cases. [ABSTRACT FROM AUTHOR]

Melting, solidification, and viscosity properties of multicomponent Fe-Cu-Nb-Mo-Si-B alloys with low aluminum addition (up to 0.42 at.% Al) were studied using an oscillating cup viscometer. It is shown that melting and solidification are divided into two stages with a knee point at 1461 K. The temperature dependences of the liquid fraction between the liquidus and solidus temperatures during melting and solidification are calculated. It has been proven that aluminum accelerates the processes of melting and solidification and leads to an increase in liquidus and solidus temperatures. In the liquid state at temperatures above 1700 K in an alloy with a low aluminum content, the activation energy of viscous flow increases. This growth was associated with the liquid–liquid structure transition, caused by the formation of large clusters based on the metastable Fe23B6 phase. Aluminum atoms attract iron and boron atoms and contribute to the formation of clusters based on the Fe2AlB2 phase and metastable phases of a higher order. [ABSTRACT FROM AUTHOR]

A computational fluid dynamic modeling framework is developed to quantify frictional losses, assess the energy efficiency of transport, and characterize the mixing behavior of methane-hydrogen blends across representative regions of a large gas network such as transmission, distribution, and household pipeline sections. The principal conclusions from the present study are: (i) The increase in the energy required for transporting hydrogen as methane-hydrogen blends depends on the volume fraction of hydrogen, the nature of the flow conditions, pipe diameter, pipe roughness and pipe bends. (ii) Pipelines that have larger surface roughness or smaller diameters or those with bend sections require greater energy for transporting gas blends. (iii) The methane-hydrogen gas blends develop a core-annular flow pattern under steady state conditions with the denser and more viscous methane flowing near the pipe wall as the annulus while the less dense and less viscous hydrogen concentrated more towards the mid-sections of the pipelines. [Display omitted] • Pipeline roughness increases transport energy requirements due to friction. • Larger diameter pipelines transport hydrogen with more energy efficiency. • Hydrogen content and flow conditions determine energy costs for transporting blends. • Hydrogen gas blends develop core-annular flow pattern under steady state conditions. [ABSTRACT FROM AUTHOR]

Based on one 5-point and two 2-point stencils, a nonlinear weighted scheme adaptive to the weighting of multi-order interpolation candidates for shock capturing is proposed. The JS weight function is adopted. The smoothness indicator of the 5-point stencil is specially designed with a higher-order leading term similar to the reference global smoothness indicator τ in the Z weighting. The design maintains that the nonlinear weights satisfy the sufficient condition for the scheme to avoid degradation at extreme points. The form of the weighting is also simplified, obviously reducing the weighting procedure's computational costs. Inviscid and viscous compressible flow problems are simulated to test the performance of the newly designed nonlinear weights based on the weighted compact nonlinear scheme. The numerical results show no obvious oscillations near the discontinuity, and the resolution of both discontinuities and smooth regions is better than JS, Z, and ZQ weighting. [ABSTRACT FROM AUTHOR]

This study explores forced convection in a viscous, electrically conducting fluid over a stretching sheet with variable thickness. It examines the effects of a varying free stream, magnetic field, and viscous dissipation on flow and heat transfer. The governing equations for mass, momentum, and energy are converted into ordinary differential equations using similarity transformations and solved numerically with the finite difference method. The results reveal dual solutions within specific parameter ranges: one stable and aligned with natural phenomena, the other unstable with higher skin friction and velocity. Viscous dissipation significantly alters velocity and temperature profiles. These insights are valuable for optimizing flow conditions in applications such as metal sheet cooling and polymer processing. [ABSTRACT FROM AUTHOR]

A vertically oscillating plate with a temperature difference and mass diffusion is used to investigate the role of thermal radiation and chemical reaction in the unexpected convection flow of a viscous unstable rotating fluid. The results of the calculations indicate that the fluid is a grey medium that absorbs and emits radiation. With time, both the plate's and the surrounding environment's temperatures and concentrations rise. The Laplace transform method finds solutions to the dimensionless governing equations for a plate, which is oscillating in its own plane. In relation to one another, the phase angle, radiation parameter, Schmidt number, thermal Grashof number, mass Grashof number, and time are all investigated. [ABSTRACT FROM AUTHOR]

Dynamically loaded soils can exhibit large-deformation flow liquefaction or limited-deformation cyclic mobility mechanisms, depending on the initial state of the soil. Undrained cyclic triaxial tests were performed on saturated calcareous and silica sand specimens prepared with different relative densities and subjected to various effective confining pressures and cyclic stress ratios to study the flowability of viscous liquefied sand. The cyclic shear stress–strain rate relationship for calcareous and silica sands transitioned from an elliptical shape to an asymmetric Lamé curve shape as excess pore pressures accumulated under cyclic loading. The asymmetric Lamé curve–shaped relationship demonstrates that the saturated sand exhibited low shearing resistance and high fluidity under elevated excess pore pressures for the conditions evaluated. The average flow coefficient, κ¯ , defined as the maximum shear strain rate triggered by the unit average cyclic shear stress, and the flow curve defining the variation in κ¯ with the number of loading cycles, describes the flowability of the saturated sand and is used to quantify the cyclic failure potential of the saturated sand under a proposed viscous fluid flow failure criterion. The effect of relative density, effective confining pressure, and cyclic stress ratio on the flow curves and the number of cycles to failure under the proposed viscous fluid flow failure criterion is discussed and compared with the cyclic resistance determined from widely used excess pore pressure– and strain-based cyclic failure criteria. The viscous fluid flow cyclic failure criterion is more stringent than these alternative criteria, and the corresponding axial strains are consistent with those associated with liquefaction triggering under cyclic strain approach. [ABSTRACT FROM AUTHOR]

An incompressible, steady-state, and three-dimensional rotatory micropolar fluid confined by the parallel co-axial disks is examined. The fluid motion is triggered by the two rotating stretchable disks. The heat transfer aspects in flow scenario are incorporated through Maxwell–Cattaneo law. The system of coupled momentum, angular momentum, and energy equations is first normalized in accordance with similarity variables and then is solved through numerical based built-in software using Runge–Kutta–Fehlberg (RKF-45) procedure. The nature of obtained physical constraints are reported on microrotation, temperature and velocity profiles. Three-dimensional flow configurations along with their respective contours are plotted against the engineering quantities for better flow visualization. Shear stresses, couple stresses, and heat transmission rate at the surfaces of higher and below disks are computed for the selected dimensionless quantities values. It is perceived that the influx flow along radial direction shifts toward faster moving disk for larger values of stretching parameters. The rotational effect of fluid elements along tangential direction is observed against the combined influence of micropolar parameters. The temperature field is reduced in the left half of the central plane while it is enhanced in the right half of the central region for increased values of the thermal relaxation time parameter. The results are also presented and compared well with published literature in limiting case of the Newtonian/viscous fluid flow. [ABSTRACT FROM AUTHOR]

Interactions between fluid flow and elastic structures are important in many naturally occurring and engineered systems. This review collects and organizes recent theoretical and experimental developments in understanding fluid-structure interactions at low Reynolds numbers. Particular attention is given to the motion of objects moving in close proximity to deformable soft materials and the ensuing interplay between fluid flow and elastic deformation. We discuss how this interplay can be understood in terms of forces and torques, and harnessed in applications such as microrheometry, tribology, and soft robotics. We then discuss the interaction of soft and wet objects close to contact, where intermolecular forces and surface roughness effects become important and are sources of complexity and opportunity. [ABSTRACT FROM AUTHOR]

In this study, we introduce a way to control the viscosity of the numerical approximation in the Godunov-like smoothed particle hydrodynamics (SPH) methods. This group of SPH methods includes momentum and energy fluxes in the right-hand sides of the equations, which are calculated by the solution of the Riemann problem between each pair of neighboring particles within the support radius of the smoothing kernel, which is similar to the procedure for the calculation of fluxes across cell boundaries in Godunov schemes. Such SPH methods do not require the use of artificial viscosity since the significant numerical viscosity is already introduced by a Riemann problem solution. We demonstrate that such a numerical viscosity may be measured and obtain the explicit expression for it depending on smoothed particle properties. In particular, we have found that Godunov-like SPH method with interparticle contact algorithms produces numerical viscosity several orders of magnitude higher than physical viscosity in materials. Modern approaches, such as SPH with monotonic upstream-centered scheme for conservation laws or weighted essentially non-oscillatory reconstruction techniques, have not only lower numerical viscosity but also too large for modeling real-world viscous flows. By constructing a correcting viscous stress tensor based on the analytical solution for discontinuous viscous flow, it is possible to reduce the viscous stresses of numerical origin. The use of such a correction makes it possible to improve the agreement with experiments in the simulation of viscous flows without using schemes of higher order reconstruction. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to inspect the unsteady MHD mixed convective Couette flow of viscous dissipative fluid in a vertical channel filled with porous material. The steady state analytical solutions of temperature, velocity, frictional force and heat transfer rate are obtained using the Homotopy perturbation method (HPM). The implicit finite difference technique is used to solve the transient leading equations numerically. Plots and tables with the dynamic flow parameters and dimensionless variables are displayed. During this computation, it was found that raising the Darcy parameter (Da) and the mixed convection (Gre) parameters both push the fluid flow upwards, but increasing the magnetic field's values had the opposite effect (M). [ABSTRACT FROM AUTHOR]

The presented work aims to develop a novel technique for obtaining the solution of linear and nonlinear Partial Differential Equations (PDEs). This technique is based on applying a collocation method with the aid of Bernoulli polynomials and the use of such an algorithm to solve different types of PDEs. The method applies the regular finite difference scheme to the main problem and transforms it into an algebraic system. The obtained system is then solved, the unknown coefficient is acquired, and an approximate solution for the problems is achieved. Some test results of famous equations, including the telegraph, viscous Burger, and modified Burger equations, are tested to ensure that the provided algorithm is effective and robust. In addition, a comparison is provided with other recent techniques from the literature. The current technique proves to have high accuracy concerning the error measure and through graphical representation of the solution. [ABSTRACT FROM AUTHOR]

Unsteady, viscous compressible flow is numerically simulated within first two stages of a low pressure turbine of a gas turbine engine under different clocking of its stator blades rows. Zonal DES turbulence modeling has been used for flow simulations. Time-dependent wake flow trajectory is modeled and visualized within the blades passages. All characteristics of the passage wake flow, including its V-shape motion, re-orientation, elongation, expansion, and stretching, are properly simulated. Unsteady flow field results together with those of general aerodynamic performance of the optimum and worst clocking cases are presented and compared with each other. Analyses of the flow simulation results showed that the optimum clocking of the blades rows occurs while the upstream wake flow impinges on the downstream stator blade leading edge region. Final results demonstrated that under the optimum clocking of the second stator, the inlet total pressure of the second rotor blades row and its output power increase by 0.1% and 0.336%, respectively. Consequently, efficiency of the second stage increases by 0.35%. In addition, total output power of the whole two stages increases by 0.237%. [ABSTRACT FROM AUTHOR]

Ion irradiation can cause burrowing of nanoparticles in substrates, strongly depending on the material properties and irradiation parameters. In this study, it is demonstrated that the sinking process can be accomplished with ion irradiation of cube‐shaped Ag nanoparticles on top of silicon; how ion channeling affects the sinking rate; and underline the importance of the amorphous state of the substrate upon ion irradiation. Based on these experimental findings, the sinking process is described as being driven by capillary forces enabled by ion‐induced plastic flow of the substrate. [ABSTRACT FROM AUTHOR]

We present an overlapping domain decomposition iterative solver for linear systems resulting from the discretization of compressible viscous flows with the Discontinuous Petrov–Galerkin (DPG) method in three dimensions. It is a two-grid solver utilizing the solution on the auxiliary coarse grid and the standard block-Jacobi iteration on patches of elements defined by supports of the coarse mesh base shape functions. The simple iteration defined in this way is used as a preconditioner for the conjugate gradient procedure. Theoretical analysis indicates that the condition number of the preconditioned system should be independent of the actual finite element mesh and the auxiliary coarse mesh, provided that they are quasiuniform. Numerical tests confirm this result. Moreover, they show that presence of strongly flattened or elongated elements does not slow the convergence. The finite element mesh is subject to adaptivity, i.e. dividing the elements with large errors until a required accuracy is reached. The auxiliary coarse mesh is adjusting to the nonuniform actual mesh. [ABSTRACT FROM AUTHOR]

The present study article aims to clarify the effect of colloidal polystyrene (PS) latexes with a broad particle size distribution on film formation kinetics of multi‐walled carbon nanotube (MWCNT)‐added polymer nanocomposites by considering theoretical film formation models. Experimentally, light transmitted from nanocomposite films, each having different weight fractions of MWCNT, was recorded at different annealing temperatures via UV–Visible spectrophotometry. Optical data set was then theoretically elaborated by taking into account void closure and Prager‐Tirrell models. Activation energies of viscous flow (ΔH) and backbone motion for reptating PS chains (ΔEB), minimum film formation (T0) and healing (Th) temperatures were then computed from optical data. Experimental results revealed that ΔH required for void closure phenomenon remained unaffected by both nanofiller and size distribution of latexes. On the other hand, it was found that ΔEB for backbone motion promoted upon the addition of nano‐fillers into latex particles. Our experimental findings suggested that film formation from MWCNT‐added latex films with a broad particle size distribution mainly originates from void closure mechanism since ΔH for viscous flow suppresses ΔEB acquired for backbone motion of repeating PS chains to a great extent. Highlights: A broad size distribution effect of PS on film formation was investigated.Voids closure and Prager‐Tirrell models were applied to spectroscopic data.Activation energy of viscous flow is unaffected by size distribution of PS.Latex film formation with varying size distribution stems from void closure. [ABSTRACT FROM AUTHOR]

In this work, the relationship between the velocity of an elongated bubble and its shape is investigated, in the case where the elongated bubble flows in a viscous liquid initially at rest in a pipe. The velocity, expressed as a Froude number, depends on the angle of the inclined pipe, the Eötvös number and the buoyancy Reynolds number. The diameter of the pipe and the surface tension being fixed, the Eötvös number remains constant; this study focuses on the dependence of the velocity on the pipe inclination angle and the viscosity of the liquid. The velocity of the elongated bubble was measured for different angles between 0 and 15 degrees and for liquid viscosities 10 to 200 times that of water. As the velocity of elongated bubbles depends closely on their shape, shadowgraphy coupled with particle image velocimetry was used. The results show that the velocity of the elongated bubbles is highly sensitive to the inclination angle of the pipe and to the viscosity of the liquid, particularly for low pipe inclinations and large viscosities. In the layer of liquid located downstream of the elongated bubble, laminar flow develops rapidly in the liquid, resulting from a balance between gravity and friction at the wall. The identification of the position of the stagnation point close to the nose of the elongated bubble and the curvature of the interface at this point helps to explain why the velocity of the elongated bubble decreases for low angles and high viscosities. [ABSTRACT FROM AUTHOR]