Analysis Of Particle Motion Research Articles

Memory of shear flow in soft jammed materials.

Cessation of flow in yield stress fluids results in a stress relaxation process that eventually leads to a finite residual stress. Both the rate of stress relaxation and the magnitude of the residual stresses systematically depend on the preceding flow conditions. To assess the microscopic origin of this memory effect, we combine experiments with large-scale computer simulations, exploring the behavior of jammed suspensions of soft repulsive particles. A spatiotemporal analysis of particle motion reveals that memory formation during flow is primarily governed by the emergence of domains of spatially correlated nonaffine displacements. These domains imprint the configuration of stress imbalances that drive dynamics upon flow cessation, as evidenced by a striking equivalence of the spatial correlation patterns in particle displacements observed during flow and upon flow cessation. Additional contributions to stress relaxation result from the particle packing that reorganizes to minimize the resistance to flow by decreasing the number of locally stiffer configurations. Regaining rigidity upon flow cessation drives further relaxation and effectively sets the magnitude of the residual stress. Our findings highlight that flow in yield stress fluids can be seen as a training process during which the material stores information of the flowing state through the development of domains of correlated particle displacements and the reorganization of particle packings optimized to sustain the flow. This encoded memory can then be retrieved in flow cessation experiments.

Understanding the Energy-Saving mechanism of ceramic balls in tumbling mills

This study investigates why ceramic balls achieve superior grinding performance compared to steel balls at lower densities and lower energy consumption. Particle motion analysis shows that increasing the filling level significantly improves the velocity distribution of the grinding media. The energy input from the mill is mainly converted into the kinetic and potential energy of the media, with potential energy being dominant. As the filling level increases, the efficiency of kinetic energy conversion improves. Collisions between media and mineral particles dominate energy transfer, and lower media density enhances collision energy distribution uniformity. Reducing media density decreases grinding energy consumption while maintaining the same grinding effect.

Size-dependent effect on the interaction of surface waves in micropolar thermoelastic medium with dual pore connectivity

This research tackles a critical knowledge gap in Rayleigh surface wave propagation. It offers a comprehensive analysis that surpasses previous limitations. A size-dependent micropolar medium with unique void distributions and thermal effects is considered in this work. The constitutive relations and equations of motion for a nonlocal micropolar thermoelastic medium with double voids (MTMWDV) have been established by using Eringen’s nonlocal elasticity theory. Employing the three-phase-lag thermoelasticity theory (TPLTE), the study utilizes a wave-mode method to derive analytical solutions for Rayleigh waves in a nonlocal MTMWDV. To gain a comprehensive understanding of wave behavior, we solve the characteristic equation and analyze its roots, applying a filter based on the surface wave decay condition. A medium with stress-free and isothermal boundaries is explored through computational simulations to determine the attenuation coefficient and phase velocity. Furthermore, particle motion analysis is conducted to complement the analytical and computational approaches. Moreover, the influence of the nonlocal parameter and various thermoelastic models on these wave phenomena is investigated. The validity of the current mathematical model is confirmed through the derivation of particular scenarios.

Modified stochastic diffusion particle tracking model driven by skew Brownian motion: Analysis of sediment particle motion in turbulent flow under the effects of ejection and sweep.

Turbulent bursting events have been classified into outward interactions (Q1), ejections (Q2), inward interactions (Q3), and sweeps (Q4) in various studies. Ejections (Q2) and sweeps (Q4) have been identified as significant contributors to time consumption, momentum flux, and sediment flux. Additionally, research has shown that the distribution of these events varies nonuniformly at different bed elevations. Despite extensive investigations into the nonuniform distribution of turbulent bursting events, their impact on sediment transport has been rarely explored. In this work, we developed a modified stochastic diffusion particle tracking model (SD-PTM) driven by skew Brownian motion (SBM) using the stochastic Lagrangian approach to scrutinize sediment particle movement in turbulent flows. The model incorporates turbulent characteristics derived from a direct numerical simulation dataset, allowing for a comprehensive analysis of sediment particle dynamics. Moreover, the proposed model accounts for the nonuniform spatial distribution of ejection and sweep events, as well as the particle movement direction during these events. Numerical simulations of the model were conducted to trace sediment particle trajectories in the streamwise and vertical directions. The analysis of sediment transport involved calculating the variance of particle trajectories to examine anomalous diffusion. The model's performance was evaluated by comparing it with flow velocity and sediment concentration profiles obtained from measurements in previous studies. In conclusion, our study suggests that the motion of sediment particles in turbulent flow can be thoroughly investigated under extreme flow conditions using the modified SD-PTM driven by SBM.

Tethered Particle Motion Analysis of DNA-Binding Properties of Architectural Proteins.

Architectural DNA-binding proteins are key to the organization and compaction of genomic DNA inside cells. Tethered particle motion (TPM) permits analysis of DNA conformation and detection of changes in conformation induced by such proteins at the single molecule level in vitro. As many individual protein-DNA complexes can be investigated in parallel, these experiments have high throughput. TPM is therefore well suited for characterization of the effects of protein-DNA stoichiometry and changes in physicochemical conditions (pH, osmolarity, and temperature). Here, we describe in detail how to perform tethered particle motion experiments on complexes between DNA and architectural proteins to determine their structural and biochemical characteristics.

Estimating seismometer component orientation of the Brazilian seismographic network using teleseismic P-wave particle motion analysis and directional statistics

Seismometer component orientation is one of the most critical parameters for seismology, especially for methods that take wave field polarization effects into account, such as receiver functions, seismic anisotropy, surface wave dispersion and seismic tomography. Using P-wave particle motion combined with directional statistics, we estimated the orientation for 90 stations of the Brazilian Seismographic Network (RSBR), corresponding to 105 seismometers. The difference between the number of stations (90) and seismometers (105) is due to instrument replacement during station operation. We observed that 81 seismometers have an orientation of ±5° and 19 seismometers greater than ±5°. Only one seismometer has an orientation greater than 90° (BOAV station). ON and BR are the subnetworks of RSBR with the largest number of seismometers with orientation errors bigger than ±10° (6 for each one) and NB is the only subnetwork with no misoriented station. All the estimated orientations were close to the measured in the field, which is evidence that our approach is more accurate to detect misoriented stations than previous studies that analyzed the orientation of RSBR stations. The Watson's U2 statistical test indicated that the back azimuth deviations for Precambrian Basement and Phanerozoic Cover were significantly different, suggesting that the regional geology could affect back azimuth estimates.

Numerical simulation of the rheology of alumina abrasive particles applied to UHMWPE during the microabrasion test

The material used for 50 years in orthopedics for joint replacements is ultra-high molecular weight polyethylene (UHMWPE). Joint replacements are designed so that the metal is in surface contact with the polymeric material, and it is used in most degenerative joint disorders. A problem with joint replacements is the half-life of their UHMWPE components resulting from surface contact, leading to premature wear. This leads to the detachment of wear particles causing osteolysis. In the present investigation, a numerical simulation of the rheology of 5 μm size alumina abrasive particles applied to UHMWPE type GUR 1020 was performed by duplicating the microabrasion test. An analogy was proposed between the alumina particles observed in the scanning electron microscope (SEM) and the gravel stone obtaining a geometry similar to that of the alumina particles. A 3D scanner was used, obtaining different randomly selected gravel models. They were scanned and rendered to obtain the IGS files to be used in the finite element software. Using Archad’s abrasive wear theory, the volume displaced by the abrasive particles was obtained as a function of the geometry of the abrasive grains, influenced by the entry position of one or more of the different cutting edges contained in the geometry, the hardness of the softer material, the value of the normal load and the sliding distance. Individual trace profiles were obtained by 2D profilometry and wear traces were analyzed by SEM. Explicit dynamic analysis of particle motion was used to simulate the entry, transition and displacement during the abrasive wear test caused by detached particles. The experimental results of the microabrasion test were compared with finite element analysis, demonstrating that simulation can be used as a reliable tool to obtain information about the type of wear of a material.

Coupling x-ray photon correlation spectroscopy and dynamic coherent x-ray diffraction imaging: Particle motion analysis from nano-to-micrometer scale

Coupling x-ray photon correlation spectroscopy and dynamic coherent x-ray diffraction imaging: Particle motion analysis from nano-to-micrometer scale

Particle motion analysis of a new three-phase fluidized bed flotation column with glass sphere particles

Analysis of the particle movement within the unit vessel is necessary for the design, optimization and scale-up of the new three-phase fluidized bed flotation column (TFC). This work aimed to examine the motion and distribution of assisted fluidized particle-glass spheres in the TFC and to provide a better assessment of particle collision and dispersion behavior by quantifying particle velocities. Tracer particles were analyzed by high-speed camera techniques to determine particle velocity fluctuations in a three-phase fluidized bed consisting of glass spheres, water, and bubbles. A correlation model for determining the particle velocity in a three-phase fluidized bed is proposed after a systematic analysis of the particle velocity. The model covers a wide range of superficial gas velocities (0–0.339 m/s), superficial liquid velocities (0.169–0.425 m/s) and initial static bed heights (0.162–0.262 m). Aiming to evaluate particle collisions in the TFC, this paper derives the particle collision frequencies using a modified collision model and investigates the effect of a wide range of operating parameters on particle collisions. Finally, a new method for estimating dispersion due to particle motion is developed based on the study of particle dispersion coefficients.

An Investigation of Particle Motion and Energy Dissipation Mechanisms in Soil–Rock Mixtures with Varying Mixing Degrees under Vibratory Compaction

Soil–rock mixture (S–RM) is a heterogeneous granular material commonly used in engineering applications, but achieving uniform particle mixing is challenging. This study investigated the effect of mixing homogeneity on the compaction of S–RM using the discrete element method (DEM). Specimens with varying degrees of mixing were modeled under realistic vibration loading. The results showed that a higher degree of mixing resulted in a smaller void ratio after compaction. The analysis of particle motion and energy dissipation revealed that not all particle motion during vibration compaction was aligned with the direction of the particle system. However, rotation was more prevalent and contributed to densification. Dashpot energy dissipation did not solely promote changes in the void ratio, while slip energy dissipation did lead to changes in the void ratio, but not entirely towards compaction. Rolling slip energy dissipation primarily occurred during the stage of void ratio changes and significantly promoted compaction. The change in strain energy aligned with the trend of the void ratio but did not directly contribute to its promotion.

Particle motion analysis and performance investigation of a fertilizer discharge device with helical staggered groove wheel

Enhancing the uniformity of fertilizer particles flow is crucial in fertilizer discharge device research, and the analysis of particle motion process contributes to improving fertilization performance. In this study, the discrete element method was employed to conduct a phenomenological analysis and numerical investigation of the particle motion characteristics influenced by structural feature parameters of the groove wheel-type fertilizer discharge device. A performance evaluation model based on the uniformity of fertilizer discharge and supplemented by the flow characteristics and mechanical properties of particles was established. The results demonstrated that the particles flow within the fertilizer bin exhibits a recirculating surge induced by the rotation of the groove wheel. The geometric morphology of the outer edge grooves and their spatial distribution along the groove wheel circumference affect the uniformity of fertilizer filling and discharge mass flow rate. The force exerted on the fertilizer particles and their potential breakage are primarily concentrated during the fertilizer compaction stage, while the particles flow forms a convergence due to the sliding of the fertilizer along the discharge slope. After optimization, the discharge CV is reduced from 91.54 % to 31.48 %, and the uniformity is improved by 60.06 %. This study proposes a helical staggered groove wheel fertilizer discharge device structural model, providing new insights for the optimization of agricultural fertilization machinery equipment.

Analysis of particle motion and wear characteristics for mixed particle sizes in centrifugal pumps

Analysis of particle motion and wear characteristics for mixed particle sizes in centrifugal pumps

Lateral Variations Across the Southern San Andreas Fault Zone Revealed From Analysis of Traffic Signals at a Dense Seismic Array

AbstractWe image the shallow seismic structure across the Southern San Andreas Fault (SSAF) using signals from freight trains and trucks recorded by a dense nodal array, with a linear component perpendicular to SSAF and two 2D subarrays centered on the Banning Fault and Mission Creek Fault (MCF). Particle motion analysis in the frequency band 2–5 Hz shows that the examined traffic sources can be approximated as moving single‐ or multi‐point sources that primarily induce Rayleigh waves. Using several techniques, we resolve strong lateral variations of Rayleigh wave velocities and Q‐values across the SSAF, including 35% velocity reduction across MCF toward the northeast and strong attenuation around the two fault strands. We further resolve 10% mass density reduction and 45% shear modulus decrease across the MCF. These findings suggest that the MCF is currently the main strand of the SSAF in the area with important implications for seismic hazard assessments.

Analisis Pergerakan Partikel terhadap Rekaman Mikrotremor di Permukaan Sungai Bawah Tanah Bribin, Kawasan Karst Gunung Sewu

Microtremor has been widely used to determine soil characteristics and dynamics. In this research, particle motion analysis was conducted on 15 microtremor data recordings around the surface of the Bribin Underground River in the Gunungsewu Karst Area. Spectrum analysis was conducted as a basis for determining the frequency range for the particle motion analysis process. Particle motion analysis was only carried out on the horizontal component of the microtremor signal which is expected to provide a representation of the river flow path. The results of particle motion analysis of microtremor recordings in the surface area of the Bribin Underground River show that there are only two points that have a motion-resultant oriented to certain direction, which is perpendicular to the river channel.The points are A4 and B4 which are located in the eastern part of the river flow path.

Ultrahigh-resolution shear-wave reflection imaging of vertical-component data in a quick-clay prone to landslide area in southwest Sweden

We have investigated the potential of ultrahigh-resolution seismic reflection imaging of vertical-component data to identify hazardous conditions in a quick-clay landslide area in southwest Sweden. A high-fold survey with a fine shot and receiver spacing has been acquired using a 5 kg sledgehammer, vertical hit, with the objective of producing a high-quality unaliased shear-wave reflection section retrieved from vertical-component data. On the receiver side, 1C wireless recorders are deployed in a fixed geometry juxtaposed to a landstreamer of 3C-microelectro mechanical system (MEMS)-based units, which recorded in a roll strategy to cover most of the profile length. Particle motion analysis of main reflections has been conducted on the 3C MEMS sensors, given their side-by-side location with the wireless recorders, to inspect the wave polarization. Distinct shear-wave reflections in an extremely slow shear velocity medium (70–100 m/s) imply a vertical super resolution of 1–2 m down to a bedrock level of 40 m deep. Interestingly and as shown in earlier studies, quick clays appear to overlie the coarse-grained horizons justifying why their high-resolution imaging can be significant for quick-clay landslide studies and a better understanding of potential risks. Two shallow reflections are delineated through a combination of first-break traveltime tomography for P and S waves and reflection seismic processing for P- and S-reflections of the vertical-component data. After seismic imaging and borehole data correlation, the shallowest reflection is interpreted to be from coarse-grained materials interbedded within normally consolidated clays and the deepest one from an undulating bedrock. Interpretations of the S-S processing outcomes indicate that the coarse-grained layers are not homogeneous because of the generation of strong shear-wave diffractions, suggesting the presence of either large boulders or patchy sandy-silty conditions.

Analysis and Modeling of Non-Spherical Particle Motion in a Gas Flow

This paper describes the reviews of the recent works in analysis, modeling, and simulation of the motion of a non-spherical particle. The motion of the non-spherical particles was analyzed in detail by means of a fully resolved direct numerical simulation (DNS). From the DNS data, the PDF-based drag coefficient model was proposed and applied to the particle dispersion simulation in an isotropic turbulent flow to assess the effect of the particle shape by comparing it with the motion of a spherical particle. Moreover, the model was applied to a large-eddy simulation (LES) of particle dispersion in an axial jet flow and validated by comparing it with the experimental data. Results showed that the effect of the particle shape was clearly observed in the characteristics of the particle dispersion in the isotropic turbulent flow by evaluating the deviation from the Poisson distribution (D number) and the radial distribution function (RDF). It was found that the non-spherical particle’s representative Stokes number becomes larger as the sphericity increases. Furthermore, it was also revealed that the effects of the particle size distribution and the shape observed in the experiment was precisely captured by the LES that coincided with the trend found in the isotropic turbulent flow.

Effect of particle arrangement and density on aerodynamic interference between twin particles interacting with a plane shock wave

Unsteady drag, unsteady lift, and movement of one or two moving particles caused by the passage of a planar shock wave are investigated using particle-resolved simulations of viscous flows. The particle motion analysis is carried out based on particle-resolved simulations for one or two particles under a shock Mach number of 1.22 and a particle Reynolds number of 49, and the particle migration and fluid forces are investigated. The unsteady drag, unsteady lift, and particle behavior are investigated for different densities and particle configurations. The time evolution of the unsteady drag and lift is changed by interference by the planar shock wave, Mach stem convergence, and the shock wave reflected from the other particle. These two particles become closer after the shock wave passes than in the initial state under most conditions. Two particles placed in an in-line arrangement approach each other very closely due to the passage of a shock wave. On the other hand, two particles placed in a side-by-side arrangement are only slightly closer to each other after the shock wave passes between them. The pressure waves resulting from Mach stem convergence of the upstream particle and the reflected shock waves from the downstream particle are the main factors responsible for the force in the direction that pushes the particles apart. The wide distance between the two particles attenuates these pressure waves, and the particles reduce their motion away from each other.

Knowledge Analysis of Charged Particle Motion in Uniform Electromagnetic Field Based on Maxwell Equation

Abstract We study the motion states of charged particles in a homogeneous electromagnetic field based on the Maxwell equations. The authors propose the charged particle properties analysis based on the Maxwell equation and electromagnetic field, first explain the Maxwell equation and electromagnetic field properties analysis, and then analyze the charged particles in the composite field (electric and magnetic field coexistence). List the important knowledge points about the motion of charged particles in an electric field, and determine the center of the circle where the charged particles move in a circular motion, simulate the motion of charged particles in a uniform orthogonal electromagnetic field, if at, the trajectory of the charged particle is a short-amplitude cycloid, if, the trajectory of the charged particle is a long cycloid, if. The realization of simulation is mainly based on theory to obtain phenomena, although it has extensive practical significance for confirmatory experiments, when inspiring and guiding students to carry out inquiry learning, physics teachers should still organically combine simulation experiments with traditional experimental teaching, teacher explanations, and student experiments in teaching design and teaching implementation, in order to cultivate students' independent inquiry ability and experimental innovation ability.

Velocity Contrast across the Zhaotong-Ludian Fault in Southwest China from the Analysis of Fault Zone Head Waves and Teleseismic P-Wave Arrivals

Abstract We image the Zhaotong-Ludian fault (ZLF) in the southeastern margin of the Tibetan plateau (SE Tibetan plateau) using waveforms from local and teleseismic earthquakes recorded by 14 seismic stations. We identify two types of fault zone head wave (FZHW) from two clusters of earthquakes by applying an automatic picking algorithm and a horizontal particle motion analysis. The first type of FZHWs shows a linear time–distance moveout and is only observed at stations on the southeast side of the fault in the northeastern section of the ZLF. The moveout slope suggests an average cross-fault velocity contrast of ∼2.5%. The second type of FZHWs exhibits a constant moveout and is recorded by stations on both sides of the ZLF in the southwestern section from a cluster of earthquakes located in a low-velocity zone. The difference in cross-fault velocity contrast between the northeast and southwest segments of the ZLF is also confirmed by teleseismic P-wave travel-time data. We attribute the prominent velocity contrast in the northeast section to a lithological difference between the South China block in the southeast and the Daliangshan subblock on the northwest side of the fault. The striking difference between the northeast and southwest sections also implies that earthquakes nucleating in one segment would hardly rupture through the entire fault, which can significantly affect our estimates of the maximum magnitude of future earthquakes occurring on the fault.

Bifurcation diagram and a qualitative analysis of particle motion in a Kerr metric

We investigate the dynamics of particles in a Kerr metric which describes the gravitational field in a neighborhood of a rotating black hole. After elimination of cyclic coordinates this problem reduces to investigating a Hamiltonian system with 2 degrees of freedom. This system possesses an additional Carter integral quadratic in momenta and hence is integrable by the Liouville-Arnold theorem. A bifurcation diagram is constructed and a classification of the types of trajectories of the system is carried out according to the values of first integrals. In particular, it is shown that there are seven different regions of values of first integrals which differ in the topological type of the integral submanifold. Pro-and-retrograde trajectories of particles are found.