Motion Of Solid Particles Research Articles

Motion of a Solid Large Spherical Aerosol Particle in a Single-Component Gas under the Influence of Carrier Medium

In the article, a motion of a large solid spherical aerosol particle in a single-component gas has been investigated. Mathematical modeling has been performed The obtained formulas allow determining the time of the particle transition into the final states, and also the distances travelled by the particle. The numerical evaluations solved with the use of these formulas demonstrate that for large initial Reynolds numbers the particle stopping distance can be significant. considering inertia, particle radius and resistance of the carrier gaseous medium to its motion.

Numerical modeling of solid particles motion in suspensions using Smoothed Particle Hydrodynamics

AbstractSuspensions and their applications can be found in many fields of mechanical, civil and environmental engineering. To consider the flow behavior as well as fluid‐solid interactions in dilute suspensions, we present 3D Direct Numerical Simulations (DNS) of a single‐phase fluid with discrete solid particles. We therefore developed a numerical implementation based on the general‐purpose particle simulation toolkit HOOMD‐blue [1, 3] extended for the usage of Smoothed Particle Hydrodynamics (SPH) [2, 5]. Since both the fluid and the solid part can be discretized by particles, SPH as a Lagrangian particle method presents a good choice to model this particular non‐linear problem. To describe solid contact and interaction forces, we consider two solid contact models. The first model is a simplified Hertz‐Mindlin contact model [4] as used in classical DEM simulations. The second model is a lubrication force model as presented by [6]. To review the results of the approach, we discuss an example with two non‐spherical solid grains in a single‐phase fluid under shear flow.

Investigating the dissipative effects of liquid-filled particle dampers using coupled DEM–SPH methods

One of the main disadvantages of solid-particle-filled dampers, generally called particle dampers (PDs), is that their performance is sensitive to vibration amplitude changes. The efficiency of PDs seems to reduce drastically with low intensity driving acceleration, especially when the acceleration level falls below that of gravity. In this paper, a new approach is investigated, in which the damper is filled with a combination of both solid and liquid fillings, in order to reduce such undesirable PD short comings. In order to quantify and understand the influence of various dissipation mechanisms, simulations were performed. The liquid motion is modeled using the smoothed particle hydrodynamics (SPH) method and the discrete element method (DEM) is used to model the motion of solid particles. In order to validate the simulation models, also a laboratory experiment was set up. This experiment consists of a damper, in this case a cylindrical acrylic container filled with spherical particles in combination with distilled water, mounted on a vertical leaf spring. By analyzing the free oscillation behavior of the leaf spring, the corresponding damper performance is characterized. The insights gained during experiments were then utilized to identify and validate the DEM and SPH models, respectively. Initially, damping behavior of dampers with solid filling and liquid filling are analyzed independent of each other. Then, these two configurations are compared with dampers with a combination of both solid and liquid fillings. In order to model solid–liquid dampers a coupled SPH–DEM approach is used. Experimental and simulation results show that dampers with a mixture of solid and liquid filling perform better than purely solid-filled or purely liquid-filled dampers, especially under low intensity driving accelerations. The main reasons behind this effect are believed to be that the solid particles with the additional hydraulic forces due to an added liquid are more agile leading to more relative motion and thereby leading to more energy dissipation. Moreover, the violent sloshing motion of the liquid through the tiny gaps, created by solid particles, also leads to more energy dissipation.

TWO-PHASE TURBULENT FLOW IN STRAIGHT HORIZONTAL CHANNELS WITH A SQUARE CROSS-SECTION TAKING INTO ACCOUNT THE INFLUENCE OF VERTICAL FORCES

The paper presents a numerical simulation of a two-phase turbulent flow in pneumatic transport through straight horizontal channels with a square cross-section. The transport of solid particles of ash and flour is taken as the two-phase flow, while air is chosen for the transporting fluid. The motion of solid particles occurs due to the aerodynamic forces of the transporting fluid. The paper considers the motion of solid particles by taking into account the influence of vertical forces, which act on the transported solid particles. In flow modelling, the transported solid particles are reduced to spherical shapes. The stress model of turbulence is corrected by taking into account the influence of the induction of secondary flows of the second kind in the gas phase. The full Reynolds stress model is used to model the turbulence, with the application of the complete model for turbulent stresses and turbulent temperature fluxes. The paper presents the results of the numerical grid with the highest resolution above which the increase of the mesh density does not affect the obtained results. The diagrams of the positions of the transported solid particles are provided for cross-sections normal and parallel to the flow direction.

Influence of swirling intensity on lump coal particle pickup velocity in pneumatic conveying

Pickup velocity, defined as the airflow velocity requirement of the initial movement of solid particles, is the well-recognized minimum conveying velocity required of a pneumatic conveying system. To reduce the airflow velocity, the influence of swirling intensity on lump coal particle pickup velocity was studied via experimental measurements. The pickup velocity of lump coal particle was determined by the weight loss method and the whole process was recorded by a high-speed camera. Initially, a side inlet guide vanes swirling generator was developed and used to measure the effect of swirling airflow. The impact of the swirling intensity was discussed and regressed, considering the tangential flow rate, the total inlet airflow rate, and the measurement position. Subsequently, the pickup velocities of 5 to15 mm lump coal particles in axial and swirling flow field were separately determined. In addition, a normative gradual change of tangential flow rate was utilized to examine the pickup velocity variation with swirling intensity. Two points in particular are worth highlighting: (1) the lump coal particle pickup process is prone to rolling up from coal particle bed fore-end, rather than the locally layer-by-layer peeling off in axial flow field; and (2) the pickup velocity of lump coal particle first increases and then decreases with swirling number, and a cubic polynomial function has favorable adaptability to fit the relationship between the lump coal particle pickup velocity and swirling intensity. The fitting results show good agreement with the measurements, with the fitting errors being <3%.

Diffusiophoresis of a charged drop

Diffusiophoresis describes the motion of colloids in an electrolyte or non-electrolyte solution where there is a concentration gradient. While most of the studies of diffusiophoresis focus on the motion of solid particles, soft objects such as drops and bubbles are also known to experience diffusiophoresis. Here, we investigate the diffusiophoresis of charged drops in an electrolyte solution both analytically and experimentally. The drop is assumed to remain spherical. An analytical solution of the diffusiophoretic velocity of drops is obtained by perturbation methods. We find that the flow inside the drop is driven by the tangential electric stress at the interface and it directly influences the diffusiophoretic speed of the drop. Using charged oil droplets, we measure the drop speed under solute concentration gradients and find good agreement with the analytical solution. Our findings have potential applications for oil recovery and drug delivery.

Simulation of Gas Solid Flow in Quasi Two Dimensional Fluidized Bed by Immersed Boundary Method

Gas solid two phase flow occurs in multiple fields of industry. Therefore, a study researching the phenomena of this type of systems is highly adequate. In the present work subsonic, compressible flow equation in conservative Euler form is solved numerically on PC by a two step finite difference method, which is validated by the analytical solution of Sod’s shock tube problem. Fluid solid interaction is described by Immersed Boundary Method, where body force is calculated by direct forcing algorithm. Two dimensional simulation of a single solid circle shaped particle motion in the gas flow is calculated and compared to the trajectory of a particle recorded by a high speed camera measurement system in a laboratory scale quasi two dimensional fluidized bed. Image processing algorithms are implemented to track the motion of a chosen single. Comparison of experimental measurement and simulation resulted in the same magnitude of particle velocities. The possible reasons of differences and opportunities of improving the results are discussed in the study. The results are promising, and the presented preliminary simulator can be a useful tool in supporting industrial design and operation after further developments.

A Lagrangian-based SPH-DEM model for fluid–solid interaction with free surface flow in two dimensions

• A Lagrangian-based SPH-DEM coupling model is proposed to simulate fluid-solid interaction with free-surface flow. • The coupling mechanism is realised by the decoupling of the force field during the process of fluid-solid interaction. • The proposed model can capture the features of solid movement, deformation and failure with high accuracy and efficiency A Lagrangian-based SPH-DEM coupling model is proposed to study fluid–solid interaction (FSI) problems with free-surface flow. In this model, SPH uses an incompressible divergence-free scheme for simulating complex flow problems. Based on the Mohr–Coulomb criterion with tension cut, the DEM describes the characteristics of solid deformation and failure by means of contact models between particles. The coupling mechanism between SPH and DEM is realised by the decoupling of the force field during the process of fluid–solid interaction. That is, the motions of fluid and solid particles are reflected by the Navier–Stokes equations and interactions among solid particles are determined by Newton's second law in the DEM. To demonstrate the applicability of the SPH-DEM model, three case studies are used to verify the different fluid interaction situations with rigid bodies, deformable objects, and granular assemblies, respectively. The results of the proposed model shows good agreement with experimental data and indicates that it is capable of capturing the features of solid movement, deformation and failure under complex flow conditions with convincing accuracy and high efficiency.

MODELING OF THE MICROINCLUSIONS INJECTION IN POLYMER MELT PROCESS

Purpose of the study is obtaining dependencies of the parameters of the process of introducing a polymer mixture with micro sensors to a certain depth and given coordinates of the finished product.Object of the study is the process of formation of polymer products with the introduction of intelligent sensors. Research subject is technological parameters of processes of extrusion-injection molding of polymer products from the positioning of intelligent sensors. The relevance of the study - analysis of the properties of intelligent polymer materials and the expediency of using intelligent sensors in the industry in the manufacture of polymer products showed a small degree of study of this issue. Here we note that the possibility of embedding in the structure of polymeric materials of elements capable of responding to changes in force, temperature and other environmental parameters allows modeling a wide range of innovative "intelligent" materials. "Intelligent" materials are able to adequately respond to new loads, change their characteristics and form, as well as independently regulate the degree of their response to new conditions in accordance with the level of their change. Intelligent sensors allow you to monitor the processes that occur during the formation of products from "intelligent" PCMs, as well as "monitor" their condition during operation and adequately respond to changes occurring in them, due to environmental factors. The results of the study - the data available in the literature on the motion of solid particles in the fluid in the channels of process equipment cannot be used without additional analysis and calculations in different conditions of technological processes. To fulfill the task, the experimental-theoretical approach and the method of investigation were used. The obtained parametric dependences of the process of forming extrusion products from the positioned injection of microporations of a mixture of polymer with solid microparticles for materials: low pressure polyethylene of grade 15313-003, high-pressure polyethylene of mark 15803-020 and polypropylene of grade 2248-002. Certain reliability of obtaining experimental data. The relative error does not exceed 10 %. The geometric parameters of the channels and the angle of inclination of the injection mechanism are established, at which the introduction of a polymer melt with microparticles at the specified depth of immersion in the article is achieved as precisely as possible. This work may be useful in the study, design and production of equipment for the processing of polymeric materials and the receipt of products made of polymeric and composite materials.

Influence of rigid body motion on the attachment of metallic droplets to solid particles in liquid slags � A phase field study

Metallic droplets can remain attached to solid particles within liquid slags, resulting in production losses in several pyrometallurgical industries. This study shows the extension of a recently developed phase field model to include the movement of solid particles in the liquid slag in a system, considering the attachment of liquid metal droplets to solid particles in slags. The influence of this movement on the wetting of the metal droplets to the solid particles in the slag and on the resulting microstructures is investigated as a function of the velocity of the particles. For all wetting regimes, the apparent contact angle in the final microstructures was clearly larger than without particle movement. For the amount of metal attached to the particle, a clear trade-off was found between the speed of motion of the solid particle and the wetting regime.

Translational and rotational motions of small solid particles in a spatially developing turbulent boundary layer with heat transfer

Direct numerical simulations have been performed to investigate the translational and rotational motions of small solid particles in a spatially developing turbulent boundary layer with heat transfer and two-way coupling, using the Eulerian-Lagrangian point-particle approach. The particles are assumed to be smaller than the Kolmogorov length scale in the dilute gas-solid flow. The simulation results show that the motion of particles is affected by particle inertia, particle preferential concentration and two-way coupling. The mean particle angular velocity is slightly larger than the fluid one in the buffer layer since the small heavy particles preferentially accumulate in regions of high strain rate, whereas the particles rotate slower than the surrounding fluid in the close vicinity of the wall due to their high rotational inertia. In the streamwise direction, the fluid spin intensity exceeds the corresponding particle spin intensity, as a consequence of particle preferential concentration in regions of low streamwise fluid vorticity; while the opposite is true in the wall-normal and spanwise directions. In addition, the differences in the temperature, linear and angular velocities between different inertial particles can be explained in terms of the two-way interactions between dispersed particles and continuous fluid.

Effect of work of adhesion on deep bed filtration process

PurposeThe purpose of this work was to study the influence of particles and fiber material properties on the deposition efficiency. Collection of aerosol particles in the particular steps of their production, and purification of the air at the workplace and the atmospheric environment requires the efficient method of separation of particulate matter from the carrier gas. There are many papers published in the past years in which the deposition of particles on fibrous collectors is considered. Most of them assume that collisions between particles and collector surfaces are 100% effective.Design/methodology/approachFor the purpose of this work, the lattice Boltzmann model was used to describe fluid dynamics, whereas the solid particles motion was modeled by the Brownian dynamics. The interactions between particles and surfaces were modeled using an energy-balanced oscillatory model.FindingsThe results show significant impact of material properties on filter performance.Practical implicationsObtained results may provide useful information for the proper design of a filtration process and the production of filters with long service life.Originality/valueIn addition, the results presented in this work show that some assumptions of the classical filtration theory lead to an overestimation of deposition efficiency.

Проблемно-ориентированная библиотека SOWFA для решения прикладных задач ветроэнергетики

The article discusses the possibilities of the open source library SOWFA. The problem-oriented library, operating as part of the open source package OpenFOAM v.2.4.0, is intended for solving wind energy’s problems. In connection with the construction of new wind farms in the Russian Federation (Ulyanovsk region, The Republic of Adygea), the issues of designing and modeling the operation of wind farms and wind turbines are currently relevant. The article describes the structure of the SOWFA library and some of its classes. The study of the dynamics of self-organized turbulent structures and the assessment of their size are important from the point of view of maximizing the power generated by wind turbines, for analyzing the optimal location of wind turbines in wind farm. At the same time, it is necessary to study in detail the process of air’s ejection, the process of displacement of two media, in which one medium, being under pressure, affects the other and carries it in the required direction, in the area of the wind farm. The phenomenon of ejection plays a positive role and allows restoring the velocity’s deficit in the wake of the wind turbine, therefore, affects the wind capacity of wind farm. The phenomenon of ejection can be studied using the motion of solid particles. The article describes an example of adding a new KinematicCloud class to the ABLSolver solver, which describes a kinematic cloud of particles and an example of solving an applied wind energy problem for a model wind farm. The numerical domain for the model wind farm had the shape of a parallelepiped with given dimensions. The unstructured mesh contained 6 million cells. To determine the initial distribution of parameters, we used the neutral atmospheric boundary layer approximation, calculated using the Precursor method, implemented in the ABLSolver solver. The mathematical modeling of the flow parameters in the wind farm was done using the pisoFoamTurbine solver and the Actuator Line Model. In the course of calculation, for the case of a model wind farm with 12 wind turbines, the fields of averaged and pulsation values were obtained for velocity, pressure, subgrid scale viscosity, stress tensor, vorticity. The article compares the values of the dimensionless horizontal velocity in two different sections with the values obtained in the experiment. The calculations were performed using the resources of the high performance cluster of the UniCFD web-laboratory in ISP RAS.

Thermally developed peristaltic propulsion of magnetic solid particles in biorheological fluids

In this article, effects of heat and mass transfer on MHD peristaltic motion of solid particles in a dusty fluid are investigated. The effects of nonlinear thermal radiation and Hall current are also taken into account. The relevant flow analysis is modelled for fluid phase and dust phase in wave frame by means of Casson fluid model. Computation of solutions is presented for velocity profile, temperature profile and concentration profile. The effects of all the physical parameters such as particle volume fraction, Hartmann number, Hall Effect, Prandtl number, Eckert number, Schmidt number and Soret number are discussed mathematically and graphically. It is noted that the influence of magnetic field and particle volume fraction opposes the flow. Also, the impact of particle volume fraction is quite opposite on temperature and concentration profile. This model is applicable in smart drug delivery systems and bacteria movement in urine flow through the ureter.

Determination of the Velocity of Constrained Motion of Nonspherical Particles in Liquid

A semi-empirical equation has been derived based on the variation principle of the minimum of the energy dissipation intensity, which describes the ratio of the velocities of the constrained and free motion of nonspherical solid particles and is in good agreement with the experimental data.

Periodic Motions of Solid Particles with Various Morphology under a DC Electrostatic Field

This paper describes the generation of periodic motions of solid particle in an oil phase under a direct current (DC) voltage. We found that a dimer and trimer composed of spherical polystyrene (PS) particles exhibit a novel periodic motion, spin. These particles maintain their stable motion without any support from mechanical devices such as rotational axes or electronic switching devices. We expect that the simple DC micromotion is applicable for mechanical and fluidic devices employing microrobots and microfluidics.

DEM-SPH study of molten slag trickle flow in coke bed

A fully-Lagrangian numerical model was applied for understanding packed bed structures containing non-spherical solids, such as coke, and the high-temperature melt trickle flow characteristics of such beds. Smoothed-particle hydrodynamics (SPH) simulations can track the motion of liquids without discriminating between continuous and dispersed phases, and the extended discrete element method (DEM) is employed as a highly accurate method for simulation of non-spherical solid-particle motion. Based on this model, we carried out large-scale trickle flow simulations using more than 10 million particles, investigated case studies of statistical processing, and evaluated the effects of packed bed formed from various non-spherical coke samples. We found that the pathway that the passing rivulet takes down depends on the structure of the void and the neck size between two voids. If the connecting neck is larger than the capillary length λ=σ/ρg, the slag will drain. The shape of pathway was related that the solids shape factor which is considered by the projected area in the direction of gravity. Even if cokes with similar size were obtained by sieving, low sphericity cokes block slag flow through channeling voids, i.e., as the projected area of the non-spherical solid shape increased, the liquid hold up showed a tendency to increase.

Experimental studies on shock wave and particle dynamics in a needle-free drug delivery device

Recently a needle-free drug delivery device as an innovative injection device has been widely used in medical fields. Drug powders induced with the high momentum by a moving shock wave can be directly delivered into skin layers. The main component of this device is a contoured shock tube, which consists of a micro shock tube and an expanded nozzle. Drug powders and gas flows are induced by a moving shock wave generated in the micro shock tube and accelerated in the expanded nozzle. The most difficult operation is that the momentum of drug powders should be strictly controlled. In present experimental studies, a micro shock tube was designed to investigate the shock wave propagation. A sonic or a supersonic nozzle installed at the exit of the micro shock tube was studied to observe the particle acceleration. Different diaphragms for initializing incident shock waves were investigated as well. Particle tracking velocimetry (PTV) measurement was carried out to investigate the motion of solid particles. In order to visualize the shock wave propagation, Schlieren visualization method was also carried out. The primary incident shock wave and the reflected shock wave induced by the closed end of the driven section were clearly observed.

Modelling trajectories of solid particle motion in the cyclone

PurposeThis purpose of the paper is to examine the multi-channel cyclone created at the Vilnius Gediminas Technical University (VGTU) Research Institute of Environmental Protection. The paper aims to predict the possible trajectories of solid particle motion in the cyclone with reference to the mechanical forces only.Design/methodology/approachThe numerical calculations were performed on the basis of experimental results. The system of differential equations describing particle motion in the cyclone is analysed and numerically solved using Runge–Kutta–Fehlberg method. Research consists of three examples that illustrate the impact of particle density and velocity on collection and analyses the particle motion trajectories in the first and second channels of the cyclone.FindingsNumerical calculations were performed according to the data from Vilnius Gediminas Technical University Research Institute of Environmental Protection. The particulate matter of wood ash and granite were used. The collection of solid particles of different size was examined when the air inflow velocity varies from 10 to 20 m/s. The possible motion trajectories of the solid particles are defined and the parameters of collected particles have been discussed.Research limitations/implicationsThe obtained results can be used for the analysis of air cleaning efficiency and particulate matter removal from air in a multi-channel cyclone.Practical implicationsThe results lead us to improve the structure of the cyclone so as to effectively collect the solid particles of different size.Originality/valueThis paper presents the results obtained for the multi-channel cyclone created at the Vilnius Gediminas Technical University Research Institute of Environmental Protection.

On the multiplicity and symmetry of particle attractors in confined non-isothermal fluids subjected to inclined vibrations

We investigate the relationship between the motion of solid particles and related clustering dynamics under the combined influence of a large-scale convective flow and vibrations-induced small-scale displacements in microgravity conditions. Such a study is motivated by the relatively recent discovery of a new class of particle attractors for which thermal and inertial effects play a fundamental role whereas particle-to-particle interactions are not essential. The key aim is to expand the set of predictive links between flow properties and particle behavior identified in the author's earlier work (Phys. Fluids, 26(9), 093301, 2014). Insights are sought from consideration of two archetypal settings, both originating from the classical problem of a differentially heated cubic cavity, which in one case is subjected to vibrations contained in a plane parallel to one of the insulated walls (i.e. having a component in the direction parallel to the temperature gradient) and in the other experiences periodic accelerations arbitrarily oriented in space. The present study reveals that the multiplicity of the particle attractors, previously thought to be a universal number (N= 2 according to earlier studies), is not a constant. The two distinct particle attractors seen in past investigations can undergo “coalescence” and exist as a single attractor over a relatively wide range of conditions. Moreover, in addition to the ellipsoid, cylinders and conical surfaces, other shapes of the attractors, such as amphora-like or saddle-horse paraboloid structures, become possible when the vibrations are inclined with respect to the adiabatic walls.