Solid Motion Research Articles

Large-scale phase-field simulations for dendrite growth: A review on current status and future perspective

The current status of large-scale phase-field (PF) simulations for dendrite growth is reviewed by focusing on the study conducted by our group. The discussion includes the competitive growth of multiple columnar dendrites, dendrite growth with liquid flow and solid motion, permeability prediction, and cross-scale simulations using the PF method. All PF simulations introduced here were executed using a graphics processing unit (GPU) or a GPU supercomputer to significantly accelerate the PF simulations. Finally, the future perspectives of large-scale dendrite-growth PF simulations are discussed.

Novel High-Pressure Nanocomposites for Cathode Materials in Sodium Batteries.

A new nanocomposite material was prepared by high pressure processing of starting glass of nominal composition NaFePO4. Thermal, structural, electrical and dielectric properties of the prepared samples were studied by differential thermal analysis (DTA), X-ray diffraction (XRD) and broadband dielectric spectroscopy (BDS). It was demonstrated that high-pressure-high-temperature treatment (HPHT) led to an increase in the electrical conductivity of the initial glasses by two orders of magnitude. It was also shown that the observed effect was stronger than for the lithium analogue of this material studied by us earlier. The observed enhancement of conductivity was explained by Mott's theory of electron hopping, which is more frequent in samples after pressure treatment. The final composite consisted of nanocrystalline NASICON (sodium (Na) Super Ionic CONductor) and alluaudite phases, which are electrochemically active in potential cathode materials for Na batteries. Average dimensions of crystallites estimated from XRD studies were between 40 and 90 nm, depending on the phase. Some new aspects of local dielectric relaxations in studied materials were also discussed. It was shown that a combination of high pressures and BDS method is a powerful method to study relaxation processes and molecular movements in solids. It was also pointed out that high-pressure cathode materials may exhibit higher volumetric capacities compared with commercially used cathodes with carbon additions.

Theoretical foundations of overvector structures in general problems of machine introduction

Currently, there is a helical calculus, as a vector algebra of complex vectors of motion of solids in space. The article shows that the helical calculus is not a complete description of the motion of solids. Since, the helical calculus describes only the movement along a helical line, and does not take into account the movement with flips. The article shows that for a complete description of the motion of solids in space, it is necessary to introduce a new algebra of motion with a revolution ("calculus of wheels"), similar to the algebra of screws. The introduction of an additional algebra of complex vectors of turns (wheels) entails the need to develop an algebra of bicomplex (Hypercomplex) vectors of "motors" describing a complete combination of all types of movements of solids in space. Keywords: helical calculus, solid, vector, space, motion with revolution, helical line, wheel motion, bicomplex vector

Analysis method of the water inrush and collapse in jointed rock mass tunnels: A case study

Water inrush disaster occurs easily when the tunnel is close to the water rich fault fracture zone. To clarify the disaster evolution process and the critical thickness of the water-resistant rock mass is the key problem of the prevention and control of water inrush disaster in jointed rock tunnel. However, the water inrush disaster in jointed rock tunnels involves solid-fluid interaction, and the conventional single-phase numerical method is difficult to realize the real simulation of the disaster. To solve this problem, we gave full play to the advantages of the discontinuous deformation analysis method (DDA) in simulating solid motion and the smoothed particle hydrodynamics method (SPH) in simulating fluid motion, and the two-dimensional DDA-SPH (2D DDA-SPH) method was used to simulation the solid-fluid interaction in the water inrush disasters. Firstly, the 2D DDA-SPH method was used to replicate the solitary wave experiment, named Scott Russell's wave generator, and the result of the simulation was almost the same with experiment, which verified the accuracy of 2D DDA-SPH method in simulating solid-fluid interaction dynamic problems. Secondly, taking the Yonglian Tunnel as the research object, we simulated the water inrush disaster in the F2 fault of Yonglian Tunnel under the condition of different thickness of water-resistant rock mass. Based on the results of the simulation, the critical thickness of water-resistant rock mass was determined, which was about 5m. Lastly, we analyzed the process of the water inrush disasters based on the movement state of the fluid near the water-resistant rock mass. And we divided the process of the water inrush disasters in the jointed rock mass into three stage, which were mutation stage, cataclysmic stage and stable stage, which provided a theoretical basis for the prevention and control of water inrush in jointed rock tunnel.

Conical spouted bed combustor to obtain clean energy from avocado waste

The advantages of spouted bed technology for waste treatment are linked to the high excess of renewable biomass waste generated by the large worldwide consumption of avocado. Therefore, the applicability of avocado waste as fuel in a novel conical spouted bed combustor was investigated. The solid cyclic movement in this reactor innovatively promotes better mass and heat transfer, as well as better energy exploitation of the waste. Local heat transfer coefficients were experimentally determined in the beds of avocado waste in the combustor to assess their heat transfer and determine their value as biofuels. The combustion of the avocado beds in the spouted bed regime was performed at 300–600 °C in a conical reactor at the minimum spouting velocity. The exhaust gas evolution was monitored over time, and the emission ratios were calculated. The combustion efficiencies of avocado seeds, skin, and their binary mixtures, determined from flue gas concentrations, were compared, and the effects of temperature and bed composition on combustion efficiency were analyzed.

A well-posed multilayer model for granular avalanches: Comparisons with laboratory experiments

Granular avalanches are dangerous phenomena characterized by the rapid gravity-driven motion of granular solids. The complex dynamics of these flows can be effectively modeled by a multilayer approach, which, however, requires particular attention to the derivation of the model equations in order to allow stable solutions. In this work, we use a well-posed multilayer model, in which the μ(I)-rheology is employed and a dilatancy law, depending on the inertial number I, is also taken into account, and systematically compare it with various laboratory experiments. The model, whose well-posedness is guaranteed by a physically based viscous regularization, describes the evolution of a preset number of superimposed granular layers. As the sidewall friction is relevant under most experimental conditions, the model is fitted here with suitable resistance terms. Moreover, non-trivial closures for the mass exchanges are introduced to avoid any unrealistic partitioning of the flow domain during the avalanche evolution, and, hence, guarantee a regular spatial discretization along the normal to flow direction. The velocity fields are compared with different experiments in unsteady state, and comparisons of both velocity and volume fraction profiles are provided with steady uniform flow experiments. The results confirm the good capabilities of the multilayer model and the underlying μ(I)-rheology in capturing the granular flow dynamics. The experimental volume fraction profiles are qualitatively well reproduced by the proposed dilatancy law, while an overestimation is observed only in the upper, more dilute flow region with a thickness of a few grain diameters.

A Novel Approach in Solving Improper Integrals

To resolve several challenging applications in many scientific domains, general formulas of improper integrals are provided and established for use in this article. The suggested theorems can be considered generators for new improper integrals with precise solutions, without requiring complex computations. New criteria for handling improper integrals are illustrated in tables to simplify the usage and the applications of the obtained outcomes. The results of this research are compared with those obtained by I.S. Gradshteyn and I.M. Ryzhik in the classical table of integrations. Some well-known theorems on improper integrals are considered to be simple cases in the context of our work. Some applications related to finding Green’s function, one-dimensional vibrating string problems, wave motion in elastic solids, and computing Fourier transforms are presented.

Comparative Analysis of Trajectory of 7.62 × 51 mm Projectiles Fired at Different Initial Velocities

The subject of the analysis involves the trajectories of 7.62 mm Lapua Scenar GB432 projectiles and “Ball” lead core projectiles manufactured by MESKO S.A. (Poland) fired at different initial velocities from 16, 20 and 26 inch long barrels. Calculations in the scope of the external ballistics concerning the characteristics of the trajectories of projectile fired from the analysed weapons were made using the PRODAS 3.5 software by Arrow Tech, using a mathematical model of the solid body movements with six degrees of freedom. During the analyses, the phenomena of the internal and transient ballistics and barrel vibrations were not taken into account. The subject of the study was only the trajectory of a projectile fired with a specific initial velocity corresponding to a barrel of a given length. The impact of wind was assessed by modifying the atmosphere model by adding a side wind blowing at a constant velocity throughout the distance. The results allowed the analysis of the effect of the barrel length and the associated initial velocity of the projectile on the nature of the projectile trajectory, especially the obtained overheight path and projectile range. The impact of the side wind on different types of projectiles was also assessed. When shooting precision rifles, it is better to use rounds with heavy projectiles, optimized for long-distance shooting. Lightweight-projectile rounds can be successfully used in the semi-automatic rifles used for support at the lowest levels, where more manoeuvrability (including barrels with a length not exceeding 20 inches) and higher fire rate is required, and, at the same, where shooting at distances exceeding 500 m is not necessary. Lightweight-projectile rounds can also be successfully used for marksmanship training at distances below 500 m, where the differences between the trajectories of different projectiles are the least.

On trajectory and velocity measurements in fluidized beds using positron emission particle tracking (PEPT)

AbstractPositron emission particle tracking (PEPT) is a non‐invasive technique that can be used for following the trajectories of particles in fluidized beds, so increasing understanding of solids motion in fluidized bed processes. We describe how PEPT is applied, how its performance is optimized, and how trajectory information can be built up into instantaneous and time‐averaged measures of particle movement. Choices and pitfalls in data processing are explained and illustrated by reference to the travelling fluidized bed (TFB) collaboration initiated by Professor John Grace.

EFFECTS OF THE AIR FLOW ON THE DYNAMIC OF PARTICLES IN THE CIRCULATING FLUIDIZED BED BOILER USING CFD SIMULATIONS

The optimum distribution of solid phase in fluidized bed system is important thing among others to achieve the best performance. One of the parameter that influences the distribution of solid is air mass flow rate. In this study, simulations of Computational Fluid Dynamics (CFD) is done where Eulerian model is used for solid particle motions and k-ε turbulence model for fluid flows. The simulations were carried out using six different air mass flow rates based on the excess air of the reactions. The air mass flow rate influenced the distribution and the velocity of solid phase, and also the pressure difference of gas inside the boiler. The results showed that the excess air between 10 % – 20 % gave the optimum results.

Lattice Boltzmann Simulation of Non-Steady-State Particulate Matter Filtration Process in Woven Fiber

To enhance the design process of high-performance woven fibers, it is vital to clarify the evolution of particle dendrites, the dynamic pressure drop, and the capture efficiency with respect to dust loading during the non-steady-state filtration process. A general element (orthogonal elliptical fibers) of woven filter cloths is numerically simulated using the 3D lattice Boltzmann-cell automation (LB-CA) method, where gas dynamics is solved by the LB method while the solid particle motion is described by the CA probabilistic approach. The dendrite morphologies are evaluated under various particle diameters, aspect ratios, packing densities, and inlet fluid velocities. For submicron particles in the “Greenfield gap” range, it is revealed that the normalized pressure drop is an exponential function of the mass of deposited particles, and the rate of increase is exactly proportional to the perimeter of the elliptical fibers. Moreover, the normalized capture efficiency is a linear function of the deposited mass. It is not advisable to increase the packing density too much, as this might simply increase the pressure drop rather than enhancing the normalized capture efficiency. It is also worth noting that the fitting slope is more likely to grow linearly once the aspect ratio exceeds 1.6, indicating that orthogonal elliptical woven fibers offer higher capture efficiency than normal orthogonal cylindrical woven fibers. The work is beneficial to gain insights into the angular distribution of particle dendrites, as well as the prediction of dynamic growth of pressure drop and capture efficiency of the elliptical fiber. These efforts could help to deepen the understanding and realize assistant designing for the filtration performance of woven fiber in the future.

Data assimilation with phase-field lattice Boltzmann method for dendrite growth with liquid flow and solid motion

Integrating phase-field simulations and in situ observation experiments is a promising approach to better understand dendrite growth during alloy solidification. To integrate simulations and experiments, we developed a data assimilation system using an ensemble Kalman filter for dendrite growth with liquid flow and solid motion. In this system, we used the phase-field lattice Boltzmann (PF–LB) model as the simulation model. Through twin experiments in which an isolated equiaxed dendrite grows with sedimentation owing to the density difference between the solid and liquid phases, we validated that the developed data assimilation system can effectively incorporate the observation data into the PF–LB simulation. In addition, we discuss the accuracy of data assimilation in different conditions by comparing the results of columnar dendrite growth with natural convection.

Chemically Reacting Jeffrey Fluid Flow Over a Deformable Porous Layer with Entropy Generation Analysis

Entropy generation of a steady Jeffrey fluid flow over a deformable vertical porous layer is analysed with consideration of a first-order chemical reaction and thermal diffusion. The porous material is modelled as a homogeneous binary mixture of fluid and solid phases where each point in the binary mixture is occupied concurrently by the fluid and solid. The combined phenomenon of solid deformation and fluid movement is taken into account. The impact of relevant parameters on the fluid velocity, solid displacement, temperature and concentration profiles is discussed. It is noticed that the Jeffrey fluid parameter enhances the entropy generation number, fluid velocity and solid displacement profiles, but a reverse effect is seen for the Bejan number. Further, entropy generation, fluid velocity and solid displacement reduce due to the higher estimates of the chemical reaction parameter, while the Bejan number enhances.

Lateral motion of a solid with a heterogeneous wettability surface driven by impacting droplets

When a droplet impacts a solid with a heterogeneous wettability surface, the generated asymmetric forces can manipulate the droplet, and its counterforces can also actuate the solid in theory. In this study, a water droplet impacting a movable hydrophobic substrate, which is decorated with a hydrophilic stripe and restrained by two linear dampers, is studied numerically. After preliminarily checking the effects of the solid mass and damping coefficient of linear dampers, the dynamic mechanisms of solid motion are explored by analysing the variations in the lateral force and instantaneous displacement distance of the solid. After that, the effects of the impact parameters on the solid lateral motion are mainly investigated, including the initial droplet diameter, impact velocity and offset distance between the impact point and hydrophilic stripe. On this basis, the reciprocating solid motion under successive droplet impacts is studied, and periodic motion with different amplitudes can be realized under appropriate impact conditions. The obtained results can shed some fresh insight into the potential applications of droplet–solid interactions, which are valuable for the collection and utilization of energy from natural environments.

An experimental study of flow–structure interaction regimes of a freely falling flexible cylinder

The fluid–structure interaction problem composed of an elongated, finite-length, flexible cylinder falling in a fluid at rest is investigated experimentally. Tomographic reconstruction of the cylinder and three-dimensional particle tracking velocimetry of the surrounding fluid, based on the Shake-The-Box algorithm, are used jointly to capture both solid and fluid motions. Starting from the rectilinear vertical fall characterized by a steady wake, focus is placed on subsequent regimes involving, mainly in the horizontal direction, periodic rigid-body motions (RBM) of weak amplitude or periodic large-amplitude bending oscillations (BO). Two RBM regimes are explored: the TRA regime where the cylinder exhibits translational oscillations in a plane perpendicular to its axis, and the AZI regime in which the body displays an azimuthal oscillation around its centre. The associated unsteady wakes are composed of counter-rotating vortices bending near the body ends to connect with the adjacent vortex rows. Specific organizations of the vortical structures are uncovered, depending on the regime. In particular, in the AZI regime, they present an antisymmetrical distribution relative to the midspan point. For a sufficiently long cylinder, BO regimes emerge, resembling the structural modes of an unsupported beam. The associated wakes exhibit a cellular organization. Within each cell delimited by two deformation nodes, two counter-rotating vortex rows are shed per oscillation cycle. Flow velocity fluctuations are in phase opposition on each side of a deformation node. For both RBM and BO regimes, frequency and phase analyses of cylinder and wake behaviours, along the span, highlight the spatio-temporal synchronization of the unsteady flow and moving body.

Highly Adaptive Liquid–Solid Triboelectric Nanogenerator-Assisted Self-Powered Water Wave Motion Sensor

Highly Adaptive Liquid–Solid Triboelectric Nanogenerator-Assisted Self-Powered Water Wave Motion Sensor

Liquid injection in a fluidised bed: Temperature uniformity

• Combination of Particle Image Velocity and Infra-Red Thermography. • Time-averaged temperature distribution for liquid injection in a fluidized bed. • Effect of droplet size distribution on the bed temperature uniformity. • Liquid agglomerates observed in the Infra-Red image as cold spots. • Solids motion affects the liquid distribution in the bed. Liquid injection in fluidized beds occurs in well-established industrial processes as fluid coking, spray fluidzed bed granulation and condensed mode gas-phase polymerisation. These processes still suffer performance issues due to their complex nature, where liquid injection adds even more complexity. In this work, the effect of liquid injection on the temperature uniformity in a pseudo-2D fluidized bed was studied using Infra-Red Thermography. The Infra-Red images were also studied to qualify the agglomeration behaviour. Injecting smaller droplets ( ∼ 90 μ m affects the uniformity of the bed more than injecting larger droplets ( ∼ 225 μ m. However, the formation of agglomerates increases with increasing droplet size. The injection velocity influences the average temperature of the bed more for the larger droplets. Additionally, increased solids motion was observed to reduce the agglomeration formation in the bed. Lastly, the particle temperature distribution does not reflect the presence of agglomerates and is thus unsuitable to quantify the agglomeration behaviour.

CFD-DEM investigation of fluid and particle motion behaviors in initial stage of spiral separation process at low solids concentration

ABSTRACT The evolution law of fluid and solid motion in the initial stage of spiral separation process is critical for mineral particle separation. The current research intends to investigate the fluid and particle motion behaviors in the initial stage of a spiral separation process using a CFD-DEM approach. The results show that the motion behaviors of fluids and particles in the initial stage of spiral separation process could be separated into three states: the development state, the transition state, and the relatively stable state. In the development state, water flows outward with a rapid change of velocity and film thickness. Meanwhile, fluid forced particles to move outward rapidly with no obvious trajectory difference. In the transition state, a collision between the slurry and the outer trough sidewall happens with changing the moving direction of fluids and particles. Following the collision, the flow field distribution tends to be relatively constant, and the light particles progressively migrate to the spiral trough’s outer edge, while heavy particles gradually move to the spiral trough’s inner edge.

A coupled cell-based smoothed finite element method and discrete phase model for incompressible laminar flow with dilute solid particles

In this paper, the cell-based smoothed finite element method (CS-FEM) empowered by the discrete phase model (DPM) is developed to solve dilute solid particles movements induced by incompressible laminar flow. In the present method, the fluid phase is solved by CS-FEM in the Eulerian framework, while particles are treated as discrete phases traced using Newton's second law in the Lagrangian framework. Meanwhile, the fluidic drag force on particles is considered to realize the one-way coupling of fluid to particles. For the fluid phase, the semi-implicit characteristic-based split (CBS) method is employed to suppress the spatial and pressure oscillations arising from the numerical solution of the Navier-Stokes equations discretized by the CS-FEM. To accurately capture the fluid velocity at an arbitrary particle position inside quadrilateral elements, the mean value coordinates interpolation is introduced. Furthermore, the motion equations for particles are solved by the fourth-order Runge-Kutta method to ensure high accuracy on particle trajectories. Several numerical examples in this paper demonstrate that the proposed method can effectively predict the effect of fluid flow on particle trajectories and position distributions in the analysis of practical and complex flow problems.

Microscopic theory of ionic motion in solids

Drag and diffusion of mobile ions in solids are of interest for both purely theoretical and applied scientific communities. This article proposes a theoretical description of ion drag in solids that can be used to estimate ionic conductivities in crystals, and forms a basis for the rational design of solid electrolyte materials. Starting with a general solid-state Hamiltonian, we employ the nonequilibrium path integral formalism to develop a microscopic theory of ionic transport in solids in the presence of thermal fluctuations. As required by the fluctuation-dissipation theorem, we obtain a relation between the variance of the random force and friction. Because of the crystalline nature of the system, however, the two quantities are tensorial. We use the drag tensor to write down the formula for ionic mobility, determined by the potential profile generated by the crystal's ions.