Particle Motion Research Articles

Study on gas–liquid–solid multiphase flow and erosion in ball valves

In industrial processes involving ball valves, gas–liquid–solid multiphase flows with continuous carrier and discrete particle phases are characterised by erosion challenges. These challenges reduce sealing performance and can lead to leakage and valve failure. To explore the characteristics of gas–liquid–solid multiphase flow and flow-induced erosion in ball valves, we conducted a combination of computational fluid dynamics numerical simulations and experimental testing. Results indicate that an increase in the gas content increases the flow coefficient, accelerates both liquid flow and particle movement and exacerbates erosion. In addition, particles are less concentrated in regions with higher gas concentrations. Erosion is primarily observed on the upstream surface and rear wall of the valve core as well as the upper side of the downstream pipeline. Severe erosion occurs more at smaller valve openings, and affected regions expand as the valve opening increases.

PRINCIPLES OF SIMULATION OF ENERGY-EFFICIENT GRANULATION PROCESSES IN A FLUIDIZED BED

The principles of physical and mathematical modeling of inhomogeneous jet-pulsating fluidization in the self-oscillating mode considering the movement of solid granulated particles on the working surfaces of the gas distributing device are investigated. The research tasks include substantiating the method of interaction between the gas phase and granular solids to ensure the implementation of heterogeneous jet-pulsating fluidization in the self-oscillating mode, experimentally determining hydrodynamic parameters to minimize the risk of stagnant zones on the working surface of the gas distributing device and formulating principles for introducing flat gas jets into orthogonal planes through a gas distribution device. The physical model focuses on creating heterogeneous jet-pulsating fluidization which is based on the formation of heterogeneous porosity in the bed of solids within the apparatus chamber. The study highlights the importance of rationally organizing the interaction mode between the gas phase and solids to ensure active circulation of granular material between 3 main technological zones: humidification, active heat exchange and relaxation. This organization enables sufficient mass transfer along the height of the bed and getting a product with the desired properties. Implementing the proposed modeling principles in equipment development will allow increasing the heat utilization coefficient by more than 60 % and will facilitate the implementation of innovative technology. The research contributes to the development of fluidization technology and its application in granulation at temperatures exceeding the melting point of thermolabile components, ensuring efficient use of resources and energy, and enhancing the environmental safety of technological processes. Bibl. 22, Fig. 11.

Water Quality Modeling of Wastewater Discharges for Prediction of Sediment Transport and Deposition in Surface Water

Sediment deposition in surface water bodies can have a range of significant impacts, affecting everything from the aquatic ecosystem to water quality and infrastructure. It can affect the availability of food sources for aquatic organisms; and change the physical structure of habitats, such as riverbeds and lake bottoms. It can equally smother aquatic plants and animals, leading to a decline in biodiversity. A model of the governing equations of particle motion and fluid flow was developed with COMSOL Multiphysics 5.3a. With a coefficient of determination of 0.99, the model result demonstrated good agreement after result validation using experimental data. According to study findings, sediments in the study area, Ele River move more slowly than sediments in the midstream which causes a high deposition of sediments at the river banks. This sediment deposition affects the irrigation system for crop production considering the ability of the sediments to block sprinkler nozzles which limits it from supplying sufficient water for the production of crops.

Acoustic properties of porous metamaterials featured by acoustic streaming, homogenization based modelling

We consider secondary effects induced by acoustic waves in viscous barotropic fluids saturating pores in elastic, or rigid scaffolds with elastically suspended particles. The asymptotic homogenization method is applied to derive models of the acoustic wave propagation and of the related acoustic streaming (AS) as the secondary effect. This phenomenon originating due to the nonlinearity (divergence of the Reynolds stress) in the Navier Stokes equation is retained using the perturbation analysis. This yields the first and the second order sub-problem enabling to linearize the model governing fluid dynamics. The local AS in the microstructure produces forces acting on the suspended particles, transforming the pore geometry, hence, modulating the acoustic properties. As the consequence, the permeability involved in both the subproblems is modified due to the slowly oscillating particles. The sensitivity analysis can be employed to introduce the homogenized coefficients of the model depending on the particle motion.

Simulation Research on the Control Method of Bow-Collapse in Gear Cold Roll-Beating

Bow-collapse is a type of geometric defect in the gear cold roll-beating process. In order to effectively control bow-collapse and improve material utilization, this paper calculates the cross-section radius of the blank according to the volume invariance principle of metal plastic deformation, and then performs FE simulation of the cold roll-beating process by using the cyclic beating of adjacent tooth spaces and intermittent blank feeding method. The flow state of metal particles is investigated, revealing that the movement of metal particles along the axial direction of the blank is the main reason for the formation of bow-collapse. This paper proposes a method to correct the cross-section radius of the blank and thus control for bow-collapse, where the loss coefficient K characterizes the state of metal particle loss in an infinitesimal thickness region on the cross-section. The analytical equation for calculating the corrected value of the cross-section radius is derived, and the corrected value is calculated. Conducted on the modified blank, cold roll-beating FE simulation results show that bow-collapse is effectively controlled, and the loss coefficient K correctly reflects the loss state of metal particles on the cross-section. The simulation results also show that after cold roll-beating, the gear teeth with standard face width and tooth depth can be obtained after two turning end faces and turning tip circle processes. The bow-collapse control method proposed in this paper effectively improves material utilization.

Analysis of the underwater acoustic environment in the Catalan Shore: Badalona and Port of Barcelona cases in the framework of the Deuteronoise JPI-Oceans Project

Maritime traffic noise pollution is a significant concern for ocean's health and living organisms' welfare, particularly in European sea basins. Research has predominantly focused on vertebrates, linking noise pollution to hearing impairment, affecting their predator and prey detection, communication, and navigation. However, recent findings suggest that tunicates, marine invertebrates related to vertebrates, may also be susceptible to noise due to their similar acoustic and particle motion sensory organs. The JPI Oceans project, Deuteronoise, addresses this research gap by characterizing noise from maritime traffic in selected European sites, investigating the effects of noise on marine deuterostomes. In this paper, we introduce the pipeline and retrieval methods, followed by an analysis of the data collected from two contrasting locations: Port of Barcelona, noise polluted area, and Badalona, non-polluted one, focusing on the noise impact on Oikopleura dioica, a representative appendicularian tunicate. Initial laboratory analyses of recorded sounds have identified different vessel and sound features, providing distinction between the two sites. With this data analysis, we aim to bring valuable insights that will enhance our understanding of maritime noise pollution. This research not only advances our knowledge of the ecological consequences of noise pollution but also informs conservation strategies for vulnerable marine ecosystems.

How SATURN is studying the impact of ship noise on the behaviour, health, energetics, and populations of aquatic organisms

The EU-funded SATURN project contributes to improve our understanding of the effects of ship noise on aquatic animals through several studies. Assessing the effects of underwater noise on aquatic animals is complex due to the diversity of taxa involved, each with their own sound sensitivity in terms of spectral and temporal aspects, as well as behavioural and physiological sensitivity to acoustic disturbances. To conduct exposure experiments on fish and invertebrates that are sensitive to the particle motion component of sound, we have developed innovative laboratory setups. Invertebrates are studied in an AQUAVIB exposure chamber, while migratory fish species are studied in a MIGRADOME swimming tunnel. The project also focuses on three marine mammal species: porpoises, pilot whales, and harbour seals. These species provide broad biological coverage of acoustic specialisations and relevant European habitats. Field data were collected using tags deployed on wild animals and dose-response relationships of marine mammal behaviour and energetics were established as a function of real-world exposure to ship noise. The effects on porpoise population are assessed using the updated DEPONS model. The results of SATURN will be transferred to stakeholders to inform management actions for the mitigation of the effects of acoustic pollution in marine habitats.

On the optical efficiency of collecting scattered radiation or telescopically imaging the measurement area in airborne acoustic pressure evaluations

Photon correlation is an optical method for calculating acoustic pressures through particle velocity measurements, involving the intersection of two focused Gaussian beams forming an interference fringe pattern. Particles within this measurement region exhibit sinusoidal motion as a result of a propagating acoustic pressure wave over the fringes, consequently scattering photons. This scattered radiation is then collected and processed to determine the particle velocity and then the acoustic pressure. In order to analyse the efficiency of the optical collection system, decoupled optical delivery configurations were implemented. In this case, instead of relying on particles moving over static fringes, moving fringes can be made to pass over an apparently static particle. To simulate this effect, a single laser beam can be modulated with a 3-D printed pattern simulating sinusoidal particle motion across fringes. Having established this alternative delivery system, suitable optical collection systems can be implemented, so that their efficiency can be analysed and assessed. This paper reports on the details of two such collection systems; analysing spherically propagated radiation and telescopically capturing the measurement area respectively.

Laboratory measurement of the effect of exposure to ship noise on mussels

The mussel Mytilus galloprovincialis is a bivalve mollusc of high commercial interest, which frequently breeds in coastal areas with high levels of ship traffic noise. Studies on the effect of this stressor on mussels are scarce, which is why we set out to design a system to study the effect of ship noise on mussel behaviour (valve opening-closure rhythms). The proposed experimental set-up uses a high frequency non-invasive valvometry system to detect shell closure reactions related to instantaneous increases in sound level. The main findings are that mussels reacted to ship noise levels above 114 dB re 1μPa (63Hz-4kHz), that most reactions occurred within 13 s after a sudden increase in level, and that there does not appear to be a clear relationship between closure depth and noise level. Although mussels may not be sensitive to sound pressure but only to the associated particle movement, the results of this work contribute to highlighting the sensitivity of this species to noise, and the need to carry out experiments with a larger number of specimens and in conditions that allow the acoustic field to be reproduced more realistically.

Detachment and transport of composition B detonation particles in rills

The partial detonation of munitions used in military exercises leaves behind energetic particles on the surface of soil. Energetic particles deposited by incomplete detonations can then dissolve and be transported by overland flow and potentially contaminate ground and surface waters. The objective of this study was to evaluate the mechanisms of transport of Composition B, a formulation that includes TNT (2,4,6-trinitrotoluene) and RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine) during overland flow. The transport of Composition B was examined using a rill flume with three flow rates (165-, 265-, and 300-mL min−1) and four energetic particle sizes (4.75–9.51 mm, 2.83–4.75 mm, 2–2.83 mm, and <2 mm). After each erosion simulation, energetic particles remaining on the soil surface were measured along with energetics dissolved in runoff, in suspended sediment, and in infiltration. Smaller particle sizes led to greater transport in both solution and sediment. The properties of the energetic compounds also influenced transport. More TNT was transported in runoff than RDX, likely due to TNT’s higher solubility and dissolution rates, however, overall, dissolved energetics in runoff and infiltration accounted for very little of the total transport. Most transport of Composition B was the result of the physical movement of energetic particles and flakes by erosion forces. This study’s results allow for improved prediction of Composition B transport during overland flow.

A two-fluid multiphase flow model coupled with the population balance equations for the flow of a multidispersed particle system

SummaryWe present a two-fluid multiphase flow model that can be applied to the flow of polydisperse particle systems. In the model, the flow of polydisperse particle systems with different N particle sizes is considered only as two phases of fluid and particle phases, without considering the individual N phases, and the motion of particles with different diameters is represented by the motion characteristics of fluid and granular phases. The equations for the granular phase are obtained by averaging the Euler equations for the particles of different particle sizes. And the velocity of particles of different particle sizes is calculated by an explicit approximation, similar to determining the slip velocity in a mixed model of multiphase flow without solving the Eulerian momentum equation. Also, the conservation equation of particles of different particle sizes was obtained by adding the source term to the population balance equation, which is caused by the difference in the particle velocity of the particles with different particle sizes. The proposed method was compared with the results of experimental studies presented in the previous study to verify the validity of the method. The method has the advantage of not only visualizing the particle size fraction distribution but also of being stable in calculation and not increasing the computational effort significantly in studying the flow of polydisperse particle systems with particle size distribution.

Application of the frozen-modes approximation to classical harmonic oscillator systems

The problems of open classical systems usually correspond to a motion of a test particle that interacts with a large number of bath oscillators. Often, the test particle itself can be considered a harmonic oscillator. For such composite systems, exact numerical solutions are available, but they can become increasingly costly for a large number of bath oscillators. Here we take inspiration from the recent work on open quantum systems and investigate the applicability of the frozen-modes approximation to such classical systems. This approach assumes that some part of the low-frequency bath modes are frozen, thus only their initial values need to be considered. We show that by applying the frozen-modes approximation one can significantly increase the accuracy of the perturbative multiple-scales solution, especially for slow baths. This approach provides a good accuracy even for strong system–bath couplings, a regime that is not accessible to straightforward applications of the perturbation theory. We also suggest a rule for the splitting of spectral density to the fast and slow bath modes. We find that our approach gives excellent results for the ohmic spectral density, but it could be applied for other similar spectral densities as well.

Free vibrations of a Continuous-discrete multi-span Beam taking into account inertial Rotation Forces

Objective. The aim of the study is to estimate free vibrations of a continuousdiscrete multi-span beam taking into account the inertial forces of rotation. The goal is to determine the spectra of natural frequencies, damping coefficients and natural modes. Method. The study is based on the methods of linear mechanics of structures; numerical and numericalanalytical calculation methods. The solution to the problem is found using the method of separation of variables. Rotational movements of particles of continuous sections are taken into account according to one of the models of the Timoshenko beam. The D'Alembert principle and hypotheses on the smallness of displacements and angles of rotation of sections are used. Result. A system of equations in matrix-vector form is obtained. The mathematical model of transverse vibrations consists of three systems of differential equations. The equation includes transverse forces, external concentrated forces, d'Alembert inertial forcesi, and linear-viscous resistance forces. The inertial forces of rotation of concentrated masses are taken into account. The boundary and other additional conditions to the equations correspond to the calculation scheme. The left end of the beam is hinged. The conjugation conditions are met at the junction of the sections. Conclusions. This random process of disturbances is very close to the processes used in deterministic problems. The amplitudes and standard deviations of displacements in the deterministic and stochastic problems almost coincide, which confirms the reliability of the proposed calculation theory. Analysis of the curves shows that the standard deviations significantly depend on the degree of correlation of the components of the vector random process of disturbances. The use of modern computing computer systems such as Matlab allows us to successfully combine the advantages of both numerical and graphical methods.

Particle motion and flow contribution in a double-row hydraulic harvesting model for deep-sea mining

The double-row hydraulic sluicing model is widely used in deep-sea mining collecting systems. However, there has been limited research focusing on its flow contributions and the relationship with particle motions. In this paper, a double-row hydraulic sluicing collector with high pickup efficiency is designed. The flow characteristics, the mechanics of the flow field, and the movement of particles in the collector are analyzed in detail through numerical calculations and experiments. The flow contributions and the collecting mechanism are clearly highlighted through aspects such as the frequency of pressure fluctuations and flow-induced vortices. The high-speed jet rolls upward after hitting the ground, forming a high-pressure area on the ground. The upwelling in the collection area is generated by the combination of the high-pressure area and the upward rolling of fluid. Regarding the particles, it is observed that particle motion can be divided into two main stages, rapid acceleration, followed by slow deceleration. Some particles may fall back when rising. Additionally, the analysis of fluid forces on the particles indicates that drag force and pressure gradient force have significant influence on particle motion.

Characterizing nodule motion in abyssal environments induced by double-row jets: A machine learning approach

Double-row hydraulic collectors are extensively utilized for deep-sea polymetallic nodule harvesting. Understanding the movement behavior of particles within the flow field is crucial for evaluating the efficiency collection system and guiding the design of deep-sea hydraulic collectors. This study first investigates the settling characteristics of particles in various deep-sea environments to assess the effects of high-pressure and low-temperature conditions on particle motion. Subsequently, the motion and force characteristics of particles under different double-row jet parameters were measured and analyzed in the laboratory using high-speed imaging. The results indicate that ambient pressure has a negligible effect on particle motion when the ambient temperature is considered. Particle is mainly lifted in an irregular spiral path by the turbulence of the upper fountain. The lifting height or force of a particle in the vertical direction is positively correlated with the frequency of horizontal fluctuations and inversely related to the average amplitude of these fluctuations. Finally, a neural network was constructed to predict the particle motion characteristics, demonstrating strong generalization and providing a reference for further use of artificial intelligence in extracting physical information of particles from the jet field. This study offers potential benefits for optimizing the design of the double-row jet collectors.

Free movement of a near-wall particle in fluid of comparable density

The fundamental problem of nonlinear interaction between a freely moving particle and surrounding fluid flow is investigated for a density ratio of order unity, with potential applications to biomedical, environmental, and aerodynamic configurations. The interaction takes place near a fixed wall, with the particle being relatively thin. A mathematical model is presented, showing the fluid pressure forces to be dominant over the mass-acceleration effects in the particle motion (in contrast with previous analyses). The added mass due to the fluid motion, thus, greatly exceeds the body mass. Numerical simulations and asymptotic analysis reveal a range of possible particle motions. The main properties emerging are: (a) the distinction between collisions with the wall and fly-away responses; (b) the time scales involved in such behaviors; (c) the pressures and velocities induced at collision; (d) the occurrence of flow reversal in certain cases; and (e) the results being independent of the particle mass and moment of inertia as well as independent of the density ratio provided that the ratio is of order unity (0–7, say) or only slightly larger (8–30, say).

Morphological properties of two-dimensional and three-dimensional bedforms in open channel flow: A flume experiments study

Bedforms are formed by sediment particles under the action of flow, which in turn affect flow and sediment movement. However, the fundamental mechanisms behind the formation and development of bedforms under varying flow conditions, the interconnection between sediment particle movement and bed morphology development, as well as the influence of bedforms on flow and sediment transport, are still not well understood. In the current study, the moveable bed load transport flume experiments under different flow conditions were done, and the development processes of two-dimensional and three-dimensional dunes formed under different flow intensities were simulated. The detailed structure of the bedforms was measured by laser scanning technology, the characteristics of the bedforms were analyzed in detail, and the relations between the formation of the bedforms and the movement of sediment particles are discussed. The results found that the correlation coefficients of the longitudinal profile curve can serve as a quick reference for distinguishing two-dimensional and three-dimensional dunes. When the crestline ratio is used as the criterion for two-dimensional and three-dimensional dunes, the relative amplitude of the dune crestline and the included angle with the flow direction should also be comprehensively considered. The lee side angles of dunes calculated using the triangle generalization method and local section tangent method are compared and show that the values obtained by the former method are only about half of that of the latter. It is also found that the lee side angles of dunes are related to the dune height. The superimposed dunes generally exist in the downstream area of the stoss side of the dunes. The local bed slopes on the stoss side of the dunes show reverse slopes. The superimposed dunes improve the local bed height and further increase the reverse slope degree of the stoss side. A streamwise ridge is an important form located in the upstream area of the dunes stoss side, and they are symmetrically distributed on both sides. Multiple streamwise ridges divide the stoss side of the dunes into relatively independent movement areas, restricting the movement of sediment particles to specific regions. According to the distribution characteristics of bed morphologies, the effects of dunes on sediment particle movement and flow energy consumption are analyzed.

On the interaction between a pulsating bubble and a particle on the rigid wall

Sand-laden cavitation poses significant challenges in high dam hydrodynamics and hydraulic machinery. This study examines the interaction between a pulsating bubble and a rigid spherical particle attached to a wall, aiming to reveal its mechanical mechanisms. Particle motion is strongly influenced by two dimensionless distances: the bubble–wall distance γ and the horizontal bubble–particle distance l, both scaled by the maximum bubble radius. Parameter γ determines the bubble's evolution characteristics and affects the particle's motion. Smaller γ means the particle is mainly influenced by bubble pulsation, while larger γ makes the particle more affected by wall vortices. The effect of l is primarily seen in the particle's velocity magnitude. A larger l causes the particle to move toward the bubble, while a smaller l makes it move away, due to the relative strengths of bubble expansion and contraction. We also identify parameter sets that result in 0 particle velocity and observe unique particle motions during bubble splitting and the formation of oblique jets. This study may further promote the application of underwater cavitation cleaning.

Numerical modeling of particle deposition in a realistic respiratory airway using CFD-DPM and genetic algorithm.

In this study, a realistic model of the respiratory tract obtained from CT medical images was used to solve the flow field and particle motion using the Eulerian-Lagrangian approach to obtain the maximum particle deposition in the bronchial tree for the main purpose of optimizing the performance of drug delivery devices. The effects of different parameters, including particle diameter, particle shape factor, and air velocity, on the airflow field and particle deposition pattern in different zones of the lung were investigated. In addition, a genetic algorithm was employed to obtain the maximum particle deposition in the bronchial tree and the effect of the aforementioned parameters on particle deposition. Reverse flow, vortex formation, and laryngeal jet all affect the airflow structure and particle deposition pattern. The mouth-throat region had the highest deposition fraction at various flow rates. A change in the deposition pattern with an increased deposition fraction in the throat was observed owing to the increased diameter and shape factor of the particles, resulting from the higher inertia and drag force, respectively. The particle deposition analysis showed that three parameters, shape factor, diameter, and velocity, are directly related to particle deposition, and the diameter is the most effective parameter for particle deposition, with an effect of 60% compared to the shape factor and velocity. Finally, the prediction of the genetic algorithm reported a maximum particle deposition in the bronchial tree of 17%, whereas, based on the numerical results, the maximum particle deposition was reported to be 16%. Therefore, there is a 1% difference between the prediction of the genetic algorithm and the numerical results, which indicates the high accuracy of the prediction of the genetic algorithm.

ISO 24543 for AE sensor sensitivity verification - support packages help to implement software scripts

This paper presents an overview over ISO 24543, the new ISO Standard for acoustic emission (AE) sensor sensitivity verification, published in Sept. 2022. ISO 24543 is based on the face-to-face setup, where a piezoelectric transmitter generates a known particle motion pulse, stimulating a directly coupled AE sensor. ISO 24543 gives two procedures, one for the determination of a transmitter’s transmitting sensitivity spectrum, referring to absolute units of nm/V, and one for the determination of the AE sensor’s receiving sensitivity spectrum, referring to absolute units of V/nm. ISO 24543 has been developed to replace the face-to-face method that delivers sensitivity spectra referring to units of V/µbar, whereby the units of µbar used for the stimulation of the SUT are neither proven nor reproducible. This paper introduces two support packages, containing descriptions and examples of software scripts that shall help experts getting their sensor verification setup quickly running. This presentation also discusses the influence of the sensor’s load on the particle motion at the ransmitter’s output.