Motion Of Dust Particles Research Articles

EXPERIMENTAL STUDY OF THE INTENSITY OF COAL DUST REMOVAL

Problem statement. Industrial sites where coal storages are located are intensive sources of dust pollution of the environment. There is an important problem of assessing the intensity of dust removal into the atmospheric air from polluted areas. Knowledge of the intensity of dust removal into the atmospheric air makes it possible to scientifically assess the impact of contaminated sites on the pollution of the environment and work zones at industrial sites. The solution to this problem can be obtained experimentally. The purpose of the article. An experimental study of the value of the air flow velocity at which the detachment of dust particles from the surface with coal begins and their removal into the air and the determination of the intensity of the emission of coal dust from the contaminated surface. Methodology. The intensity of removal of coal dust from the contaminated area was studied experimentally in laboratory conditions. The research was conducted on coal samples from DTEK “Pavlohradvuhillya”, grade “ДГ. During the research, the velocity of the air flow at which the process of movement of dust particles along the emission source began and the velocity of “detachment” of dust particles and their removal from the emission source were determined. At the second stage of experimental research, the intensity of removal of coal dust from the polluted area was determined. Scientific novelty. The values of the air velocity at which the removal of coal dust particles from the contaminated area begins were determined experimentally. The regularity of the intensity of the removal of coal dust depending on the velocity of the air flow over the contaminated area was obtained. Practical significance. The obtained experimental data make it possible to determine under which weather conditions there is a risk of dust formation and the removal of dust into the atmosphere. The empirical dependence obtained by processing experimental data can be used for a scientifically based assessment of the level of pollution of working areas at industrial sites where there are coal storage facilities. Conclusions. The value of the velocity of the air flow at which the movement of dust particles on the contaminated surface begins, as well as the value of the velocity of the air flow at which the removal of dust particles into the air begins, was determined experimentally. The resulting empirical model can be used to estimate environmental damage due to dust pollution of atmospheric air.

Evaluating the influence of filter membrane on dust particle deposition and detachment based on CFD-DEM method

The motion of dust particles significantly affects the service life and filtration efficiency of filter elements. By employing a coupled computational approach combining Computational Fluid Dynamics and Discrete Element Method (CFD-DEM), the Johnson-Kendall-Roberts (JKR) model was incorporated into the calculation of adhesive forces between particle-particle and particle-wall interactions. The influence of the membrane layer on dust particle deposition and detachment on the surface of filter elements was investigated through simulation analysis. The influence of membrane layers on the deposition and detachment of dust particles in filter elements was investigated. The results show that the addition of the membrane layer led to a 35.5% increase in the initial filtration pressure drop of the filter. However, it concurrently resulted in a diminution of the deposition depth of dust particles. By the eighth cycling period, the deposition depth of the filter element with membrane (FWM) was 2.5 mm, which was only half that of the filter element without membrane (FOM). Moreover, it was found that the cleaning efficiency of the FOM is more sensitive to reverse flow pressure, while the cleaning efficiency of the FWM is more sensitive to the duration of pulse width. These findings can help explain the mechanism of dust particle deposition and detachment and provide a basis for the design and manufacturing of filter elements.

On the similarity of rotational motion of dust particles in the inner atmosphere of comets

ABSTRACT In situ measurements of individual dust grain parameters in the immediate vicinity of a cometary nucleus are being carried by the Rosetta spacecraft at comet 67P/Churyumov–Gerasimenko. For interpretation of these observational data, a model of dust grain motion as realistic as possible is requested. In particular, the results of Stardust mission and analysis of samples of interplanetary dust have shown that these particles are highly non-spherical. In many cases precise simulations of non-spherical grain’s dynamics is either impossible or computationally too expensive. In such situation it is proposed to use available experimental or numerical data obtained for other conditions and rescale them considering similarity of the physical process. In the present paper we focus on the derivation of scaling laws of rotational motion applicable for any shape of particles. We use a set of universal, dimensionless parameters characterizing the dust motion in the inner cometary coma. The scaling relations for translational and rotational motion of dust grains in a cometary environment are proposed. The scaled values are compared with numerically computed ones in our previous works.

Explanation of the Anomalous Outburst Activity of Comet 29P/Schwassmann–Wachmann 1: The Hypothesis about the Existence of Large Satellites

We explain the anomalous outburst activity of comet 29P/Schwassmann–Wachmann 1 by the existence of satellites touching the surface of the comet nucleus at the pericenters of their orbits. It is assumed that the satellites move in eccentric orbits and a large amount of dust, the reflection of light from which causes periodic outbursts in brightness (BAA 2023), is ejected as a result of their collisions with the dust layer of the nucleus. Depending on the depth of penetration of the satellites into the dust layer, outbursts in comet brightness of various intensities occur. An improvement of the comet orbit by invoking positional observations allows the preferred direction of the ejection of material to be determined from the photocenter offset, which we interpret as the direction of the velocity vector of the largest satellite at the pericenter. The results of our numerical simulations of the ejection and subsequent motion of dust particles caused by the contact of the satellite with the dust layer of the comet nucleus explain the formation of the structures observed in the comet: the dust jets and their mirror symmetry as well as the extent of the region of material ejection from the surface of the comet nucleus.

Dynamics of dust and meteoroids due to electromagnetic transport in the heliosphere

ABSTRACT Observations of dust in the Solar system have indicated the existence of structures at higher ecliptic latitudes, the origin of which is still an ongoing debate. In a previous study, we studied how the interplanetary magnetic field affects the orbital motion of charged dust particles that are moving in co-orbital motion with Jupiter. Our findings revealed that the Lorentz force causes oscillations in orbital inclinations that lead to electromagnetic transport of the dust particles to higher ecliptic latitudes. In this work, using numerical simulations, we investigate how this transportation depends on orbital lifetime, strength of the background magnetic field, planetary mass, and distance from the Sun. In addition, we study the dynamics also outside resonance. We present our findings using the saturation curve, which gives a relation between the maximum amplitude in inclination with respect to the particle size ranging from 1 to 501 $\mu$m. We further study the influence of the solar radiation pressure, the Poynting–Robertson, and the solar wind effects on the shape of the saturation curve and find that a stronger gravitational influence of the planet leads to a steeper curve, decreasing the strength of the electromagnetic transport. The radiative forces lead to a gradual dampening of the latitudinal oscillations of particles inside resonance, while they are unchanged for objects outside of resonance. We argue that the dynamics of dust and meteoroids in the Solar system can only be understood by including space weathering effects.

Vertical Distribution of Dust Aerosol Under Conditions of Weak and Moderate Winds

The height distribution of dust aerosol in the surface layer based on the measurements made in the summer of 2020–2021 under arid conditions on the territory of the Republic of Kalmykia is considered. For the profiles of the aerosol concentration under conditions of weak winds, a characteristic gradual slope with an index close to the value of –0.5 is recorded. When the wind strengthens, the profile slope takes on values closer to the degrees known for the conditions of saltation –0.7…–1.0 (and steeper). The observed patterns can be explained by the character of motion of dust particles rising from the hot surface together with the surrounding heated air volume that differs for the fine (<1 μm) and coarse (>1 μm) particle fractions.

Comparison of the Eulerian and Lagrangian Approaches to Studying the Peculiarities of the Interstellar Dust Distribution in the Heliosphere in the Framework of the Cold Gas Model

Interstellar dust grains penetrate into the heliosphere (region in which the solar wind propagates) due to the relative motion of the Sun and the Local Interstellar Medium (LISM). Inside the heliosphere, the motion of dust particles is mainly governed by the electromagnetic force determined by the heliospheric magnetic field. Under the action of this force, the trajectories of dust grains experience intersections with each other and self-intersections. As a result, dust density accumulation regions appear. These regions are of a great interest in the context of theoretical studying and planning of upcoming space missions. The main aim of the present study is to model the interstellar dust distribution in the heliosphere and investigate the peculiarities of the number density distribution. To describe the dusty component, the cold gas model is used, while to compute the interstellar dust distribution two approaches are considered, namely, the Eulerian and Lagrangian approaches. For solving the continuity equation in the Lagrangian coordinates, the full Lagrangian method or the Osiptsov method is used. As a result, all the peculiarities of the dust distribution are investigated and it is found that they are located on caustics, i.e., the envelopes of interstellar dust trajectories. Besides it, the regular regions of overdensity (without singularities in the number density) are discovered. It is shown that the dust component accumulation regions are located in a small neighborhood of the heliospheric current sheet, at which the magnetic field changes its polarity, and in the tail of the heliosphere. The effectiveness of the Osiptsov method of solving the continuity equation is compared with the widely used Monte Carlo method (Eulerian approach). It is shown that Monte Carlo method requires extremely high resolution of computational grid to reach the level of accuracy comparable with the Osiptsov method.

Comparison of the Eulerian and Lagrangian Approaches to Studying the Peculiarities of the Interstellar Dust Distribution in the Heliosphere in the Framework of the Cold Gas Model

Interstellar dust grains penetrate into the heliosphere (region in which the solar wind propagates) due to the relative motion of the Sun and the Local Interstellar Medium (LISM). Inside the heliosphere, the motion of dust particles is mainly governed by the electromagnetic force determined by the heliospheric magnetic field. Under the action of this force, the trajectories of dust grains experience intersections with each other and self-intersections. As a result, dust density accumulation regions appear. These regions are of a great interest in the context of theoretical studying and planning of upcoming space missions. The main aim of the present study is to model the interstellar dust distribution in the heliosphere and investigate the peculiarities of the number density distribution. To describe the dusty component, the cold gas model is used, while to compute the interstellar dust distribution two approaches are considered, namely, the Eulerian and Lagrangian approaches. For solving the continuity equation in the Lagrangian coordinates, the full Lagrangian method or the Osiptsov method is used. As a result, all the peculiarities of the dust distribution are investigated and it is found that they are located on caustics, i.e., the envelopes of interstellar dust trajectories. Besides it, the regular regions of overdensity (without singularities in the number density) are discovered. It is shown that the dust component accumulation regions are located in a small neighborhood of the heliospheric current sheet, at which the magnetic field changes its polarity, and in the tail of the heliosphere. The effectiveness of the Osiptsov method of solving the continuity equation is compared with the widely used Monte Carlo method (Eulerian approach). It is shown that Monte Carlo method requires extremely high resolution of computational grid to reach the level of accuracy comparable with the Osiptsov method.

3D Active Brownian Motion of Single Dust Particles Induced by a Laser in a DC Glow Discharge.

The active Brownian motion of single dust particles of various types in the 3D electrostatic DC discharge trap under the action of laser radiation is studied experimentally. Spherical dust particles with a homogeneous surface, as well as Janus particles, are used in the experiment. The properties of the active Brownian motion of all types of dust particles are studied. In particular, the 3D analysis of trajectories of microparticles is carried out, well as an analysis of their root mean square displacement. The mean kinetic energy of motion of the dust particle of various types in a 3D trap is determined for different laser powers. Differences in the character of active Brownian motion in electrostatic traps with different spatial dimensions are found.

ON THE VERTICAL DISTRIBUTION OF DUST AEROSOL IN WEAK AND MODERATE WINDS

The height distribution of dust aerosol in the surface layer based on measurements made in the summer of 2020–2021 in arid conditions on the territory of the Republic of Kalmykia is considered. For profiles of aerosol concentration under conditions of weak winds, a characteristic gradual slope with an index close to the value of –0.5. When the wind strengthens, the profile slope takes values closer to the degrees known for the conditions of saltation. –0.7…–1.0 (and steeper). The observed regularities can be explained by the character of motion of dust particles rising from the hot surface together with the surrounding warmed air volume, which is different for fine (1 μm) and coarse (1 μm) particle fractions.

Particle simulation of the strong magnetic field effect on dust particle charging process

A particle-in-cell simulation is modeled and run on a dusty plasma to determine the effect of the magnetic field on the process of dust-particle charging through electron–ion plasma. The electric field is solved through the Poisson equation, and the electron-neutral elastic scattering, excitation, and ionization processes are modeled through Monte Carlo collision method. The effects observed from the initial density of the plasma, the initial temperature of the electrons, and the changing magnetic field are included in this simulation model. In the dust particle charging process, saturation time and saturation charge are compared. An increase in the magnetic field does not reduce time to reach the saturation state. Determining the magnetic field boundaries which depend on the physical properties of the plasma, can be contributive in some areas of dusty(complex) plasma. The applications of the results obtained here for fusion plasma conditions and space and laboratory plasmas are discussed. The results here can be applied in future simulation models with a focus on the dust particle movement and their effect on plasma, leading to the modeling of different astrophysical plasmas thorough laboratory experiments.

CFD–DEM Simulation of Dust Deposition on Solar Panels for Desert Railways

With the greening of the railway energy supply chain, large-scale photovoltaic power stations will be the best choice to integrate with the railways. Understanding the deposition mechanisms and rules of dust grains on photovoltaic panels is of great guiding significance for the operation of photovoltaic (PV) power stations. In this paper, based on computational fluid dynamics (CFD) combined with the discrete element method (DEM), the dynamic dust deposition process on solar panels was simulated, and the flow field around solar panels and the movement of dust particles in the wind were calculated. The simulation results of clay particles (d = 10 mm) and fine sand particles (d = 100 mm) under different wind speeds showed that the clay particles could follow the air flow properly, and their deposition rate was only 4.6%, while the deposition rate of the fine sand particles was up to 32%, which was determined by the inflow wind speed and cohesion parameters. An image of the non-uniform distribution of particles on the panels was given in this paper for the first time. This will provide a basis for a more accurate assessment of the impact of dust accumulation on PV output in real-world environments. These results provide a critical reference for railway photovoltaic power supply development in desertification areas.

Structural properties of a chain of dust particles in a field of external forces.

This paper presents a numerical study of the structural parameters of a one-dimensional chain of three dust particles levitating in the near-electrode layer of an rf discharge or in the stratum of a dc discharge. The model considers the motion of dust particles under the action of gravity, external electric field, the Coulomb repulsion, and the electrostatic force from the space charge surrounding the dust particles. Particular attention is paid to the effect of plasma polarization around dust particles and the wake formation under the action of the external electric field. Calculations showed that the charge of the first dust particle in the chain and the total charge of the entire chain, as well as the length of the chain, grow linearly with the external electric field strength. Obtained data are in qualitative agreement with the experimental and numerical data presented in the literature. It was shown that for a certain large value of the external electric field, the charge of the third dust particle is the smallest of all the particles in the chain. It was found that with an increase in the mean value of the external electric field, the chain of dust particles is displaced as a whole in the direction opposite to the action of the electrostatic force on them.

Aerodynamic Window Sealing of a Large-Aperture Channel for High-Power Laser Transmission

In this study, the sealing of a large-aperture channel for high-power laser transmission is achieved using an aerodynamic window. Further, a numerical model of the gas and dust particle motion in the channel is established under three different blowing schemes, and the sealing performance of the large-aperture channel is analyzed and compared under different blowing schemes. The results indicate that the larger the proportion of purge gas volume flows in the axial direction, the better the sealing effect of the channel. More importantly, the axial blowing scheme can ensure that the large-aperture channel maintains the relative positive pressure to the external environment, effectively blocking the ambient gas and dust particles blowing in. The axial blowing scheme can achieve the sealing requirements of the large-aperture channel in an environment where the ambient wind speed is less than 20 m/s, and the dust particle mass concentration is less than 8×10−3 kg/m3. In this case, the minimum non-zero z-directional wind speed is stable and positive at a position 100 mm away from the port in the channel, and the particle mass concentration is zero.

Modelling of the detachment of adhesive dust particles during bulk solid particle impact to enhance dust detachment functions

The detachment of fine adhered dust particles during bulk particle contacts is studied with an adhesive Discrete Element Method (DEM) to describe the carrier and the dust particle motion. Further, dust detachment functions are realized in a non-adhesive DEM, in which only the coarse carrier particles are tracked as one composed bulk particle. The implemented detachment functions include three criteria, a normal and a tangential lift-off condition as well as a rotational condition. These functions are benchmarked based on dust-resolved adhesive DEM simulations by varying crucial parameters in the course of particle-particle and particle-wall contacts. In advance, the adhesive force is calibrated using experimental single drop tests. The detachment criteria reflect the physical detachment of individual dust particles well assuming dust particles with a narrow size distribution. The application of the enhanced dust detachment functions therefore allows to predict dust release of individual dust particles with significantly less computing time.

Ring dust structures in a weak inhomogeneous magnetic field

AbstractExperimental results on the influence of an external inhomogeneous magnetic field created in the end areas of the coil on the dynamics of a ring‐shaped dust structure in a stratified glow discharge in argon are presented. The rotational behaviour of the ring was investigated at different magnetic fields in the range up to 16 mT. It was found that the direction of rotational motion of dust particles in an inhomogeneous magnetic field depends on the direction of its radial component. A theoretical model was proposed to explain the experimental observations.

Numerical simulation of the dynamics of dust in a rotary dust collector with an adjustable air flow

A rotary dust collector has been developed that works on the principle of a centrifugal separator. A feature of its design is the presence of a bypass recirculation channel of cleaned air with a flow regulator, two outlet pipes with flow uncoilers in the form of spiral channels. The calculation of the motion of dust particles with a density of 3000 kg/m3 and a diameter of 1 to 100 microns has been performed. Research has been carried out to improve the efficiency of the apparatus using a central compositional plan and to establish rational design and operating parameters of the mixer for recirculating and purified air.

Formation of the Thebe Extension in the Ring System of Jupiter

AbstractJupiter's tenuous dust ring system is embedded in the planet's inner magnetosphere, and—among other structures—contains a very tenuous protrusion called the Thebe extension. In an attempt to explain the existence of this swath of particles beyond Thebe's orbit, Hamilton and Krüger (2008), https://doi.org/10.1038/nature06886 proposed that the dust particle motion is driven by a shadow resonance caused by variable dust charging on the day and night side of Jupiter. However, the model by Divine and Garrett (1983), https://doi.org/10.1029/ja088ia09p06889 together with recent observations by the Juno spacecraft indicates a warm and rather dense inner magnetosphere of Jupiter which implies that the mechanism of the shadow resonance does not work. Instead, we argue that dust grains ejected from Thebe due to micrometeoroid bombardment become the source of dust in the Thebe extension. We show that large (grain radii of a few micrometers up to multi‐micrometers) charged dust grains having significant initial velocities oscillate in the Thebe extension. Smaller charged grains (with sub‐micrometer radii) ejected from Thebe do not spend much time in the Thebe extension and migrate into the Thebe ring. At the same time, if such grains are ejected from larger dust grains in the Thebe extension due to fragmentation, they continue to oscillate within the Thebe extension for years. We argue that fragmentation of large dust grains in the Thebe extensions could be the main source of sub‐micrometer grains detected in the Thebe extension.

Time-Dependent Shear Motion in a Strongly Coupled Dusty Plasma in PK-4 on the International Space Station (ISS)

Time-dependent shear motion of dust particles in a three-dimensional (3-D) strongly coupled dusty plasma under microgravity conditions was investigated using the European Space Agency–Roscosmos facility Plasma-Kristall 4 (PK-4) on the International Space Station (ISS). The dust particles, which were negatively charged, were trapped in a glow discharge plasma powered by a dc voltage that switched its polarity periodically. They self-organized themselves into a structure resembling a cold liquid. A manipulation laser beam of a circular cross section pushed a stream of particles, moving them through the surrounding sample region; its power was modulated using a rectangular pulse, causing an impulsive unsteady flow. At the onset of the impulsive motion, the flow was observed as it grew in space and time. Later, during the steady manipulation, we find the thickness of the flow region fluctuated significantly over time.

Numerical study on thermal enhancement in hyperbolic tangent fluid with dust and hybrid nanoparticles

Rheological model characterized by the shear rate dependent viscosity together with the governing laws for dust particles in fluid with the transfer of heat with the help of nano-structures are utilized for thermal analysis. Solutions of the non-dimensionalized set of constitutive models and necessary conservation laws are found by the finite element method (FEM). The simulations are recorded and important outcomes are extracted from visualization. The fluid has experienced significant retardation to its flow and wall friction on the solid boundary has depicted an increasing behavior as a function of the magnetic field. The flow slows down when viscosity varies for the shear-thinning case. The movement of dust particles in shear rate-dependent viscosity fluid increases as a function of the fluid velocity interaction parameter. Temperature profiles have been noted to increase as a function of specific heat ratio parameter. It is also observed that the temperature of dust particles in mono nanofluid is greater than the temperature of dust particles in a hybrid nanofluid. An increase in the intensity of magnetic fluid results in significant retardation to the fluid containing dust particles. However, this retardation to the flow of hybrid nanofluid is higher than the retardation experienced by the flow of mono nanofluid. Velocity of dust particles increases versus interaction parameter. Moreover, the velocity of hybrid nanofluid is affected more by the interaction parameter than the velocity of nanofluid. Thermal radiations result in a temperature rise. However, radiations emitted by the hybrid nanofluid are stronger than the radiations emitted by a nanofluid. Dust particles in nanofluid are hotter than in hybrid nanofluid. Shear stress on the solid surface increases as a function of the fluid velocity interaction parameter. Further shear stress applied by nanofluid is higher than that by the hybrid nanofluid.