CFD-DEM investigation of the flow and heat transfer characteristic of copper slag and biomass particles in a coupled waste heat utilization system

Study on flow and coke combustion characteristics of catalyst particles in an industrial regenerator

Modeling the flow of flexible rod-like particles via a novel bonded multi-super-ellipsoid DEM model

Enhancing canned motor pump performance in energy systems: A novel structure for particle wear mitigation and flow efficiency preservation

Transition mechanisms of multi-scale particle flow regimes in hydraulic lifting pipes influenced by fluid velocity and particle concentration

Analysis of particle flow regimes and energy dissipation induced by particle–wall collisions in transfer chutes

DEM study on influence of shape and stiffness on friction characteristics of flexible irregular particle flows

Abstract In mining areas with thick loose layers and widespread aquifers, mining-induced disturbances can damage rock mass and alter the seepage field, forming water-conducting channels and triggering sudden water inrush. To investigate the nonlinear coupling of fracture and seepage, a bidirectional Particle Flow Code (PFC)–FiPy (a Python-based finite volume partial differential equation solver) coupled model, combining discrete element and finite difference methods, was developed. Fracture propagation and particle skeleton instability were simulated in PFC, while porosity was transferred to FiPy to update the permeability field and capture hydraulic head and flow velocity changes. Pore pressure feedback drove particle movement, forming a closed-loop coupling. Results show that fracture evolution follows three stages: slow expansion, rapid penetration, and channel stabilization. Seepage response involves local hydraulic head drop and fast formation of high-permeability channels. Fracture density, flow velocity, and permeability increase nonlinearly, with flow velocity jumping at the critical stage and permeability rising 3–5 times in the channel zone. Bedrock (Soil4) properties exert a ‘valve-like’ control: reduced stiffness and bond strength accelerate fracture growth and permeability peaks, while increased strength suppresses them. This study reveals the physical mechanism of sudden water inrush controlled by fracture–seepage feedback and bedrock parameters, providing theoretical support and a numerical tool for water inrush prevention in high-risk mining areas.

This study examines whether twisted tape inserts in a pipe system can reduce pipe erosion under a liquid–solid flow regime. Three different twisted tape configurations were designed using 3D printing technology: tapes with one twist, four twists, and four twists with perforations. Experiments were performed using a PVC pipe with a carbon steel plate as the material under investigation. Slurries of water and silica sand were prepared with varying sand concentrations—1%, 3%, and 5%—to induce different erosion rates. The experimental results were backed by Computational Fluid Dynamics (CFD) using the discrete phase model (DPM) to predict particle flow and erosion attributes. Erosion trends were also tested through mass loss and paint loss tests. The analysis outcomes demonstrated that the one-twist, four-twist, and perforated four-twist tapes reduced the erosion rate by 18%, 39%, and 45%, respectively. Among the different configurations, the four-twist tape with holes reduced erosion the most. These results suggest that twisted tape inserts can control erosion, thereby increasing the service life of pipes that handle abrasive flows.

This study introduces a novel maximum plastic zone fracture criterion to investigate the fracture behaviour of rock bridges under compression. The proposed criterion quantifies the plastic zone dimensions at crack tips to determine the initiation and propagation of wing cracks, with the overall fracture process characterised by the evolution of the plastic zones. The influence of multi-crack interactions on wing cracks propagation is further examined, and a recommended range of correction factors for stress intensity factors (SIF) is provided. Subsequently, theoretical analyses are conducted on three specimens containing two parallel pre-existing cracks of equal length to the rock bridge. Results reveal that the distribution of pre-existing cracks significantly affects the fracture rate and mode of rock bridges, whereas the underlying failure mechanism remains consistent, primarily governed by the continuous propagation of wing cracks leading to plastic yielding throughout the rock bridge region (RBR). Furthermore, numerical simulations using PFC 2D show good agreement with the theoretical predictions, validating the proposed criterion and providing deeper insight into the fracture evolution of rock bridges.

Experimental study on shock wave interference in gravity-driven particle flow around parallel cylinders

ABSTRACT Near‐wall treatment (boundary‐layer meshing and wall functions) is a major uncertainty in solid–liquid two‐phase CFD of suspended sediment, while condition‐dependent guidelines are scarce, leading to inaccurate near‐wall fields or costly mesh trial‐and‐error. We therefore link first‐layer height selection to particle size and flow velocity. Four uniform particle sizes (90, 125, 165, 270 μm) were simulated under multiple velocities using five first‐layer heights and three wall functions (standard, scalable, non‐equilibrium). Compared with laboratory measurements, optimal schemes were identified. The optimal first‐layer height increases with particle size: about 0.5–1 times the particle diameter for 90 and 125 μm particles, about 2 times the particle diameter for 165 μm particles, and about 3 times the particle diameter for 270 μm particles; for a fixed size, it also increases with velocity. Standard wall functions work best for small particles at high velocities, whereas non‐equilibrium wall functions suit large particles at low velocities. Linear fitting and multiple regression yield a practical procedure to choose first‐layer height and wall‐function type. The proposed guideline is readily applicable to engineering CFD of sediment‐laden flows, improving prediction reliability while reducing meshing effort and computational cost.

This paper establishes a particle flow model to simulate and analyze the coal fines transported through circular and elliptical aperture screen pipes with different parameters based on the discrete element method, which combines experimental research to study the influence of confining pressure, bond strength, and drainage negative pressure on the coal fines transportability. The study shows that: 1) The increase in confining pressure has a nonlinear increasing effect on coal fine particles throughput, and there is a critical threshold. Once this value is exceeded, the particle throughput increases sharply, causing of the screen pipe. When the confining pressure reaches 6 MPa, the screen pipe is filled with coal fines and becomes clogged. 2) The stronger the bonding strength of the coal fine particles, the worse the transportability, and the stronger the anticlogging ability of the screen pipe. 3) Under the condition that the aperture density and the total aperture area are the same, the coal fines throughput of the elliptical aperture screen pipe decreases approximately linearly with the increase in aspect ratio. As particle size increases, the percentage of particles transported through the screen pipe shows an inverted "V" shape, first increasing and then decreasing. 4) Increased aperture density decreases transportability linearly, but the transportability of large-sized particles increases in the case of low density. 5) Under the combined action of confining pressure and drainage negative pressure, the variation law of transportability is basically the same as that under confining pressure, but the throughput is approximately 1.3 times the throughput under confining pressure. 6) The final optimized parameters include elliptical aperture, major axis vertical to the screen axis, aspect ratio 4, and aperture density 35/m.

Quantum complete graph self-attention network for particle flow classification

With the expansion of renewable energy deployment, characterized by its variability, stabilizing power and heat supply has become a critical issue. To address this challenge, large-scale and low-cost energy storage technologies are essential, and thermal energy storage (TES) is considered one of the promising solutions. Among large-scale TES systems, Circulating Fluidized Bed TES (CFB TES) is a technology that stores energy as sensible heat in high-temperature sand and utilizes it for power generation using high-temperature steam or steam turbines when needed, offering high compatibility with existing infrastructure. While the underlying circulating fluidized bed system is a well-established technology, precise control of circulating particle flow rates remains a technical challenge due to differences from conventional circulating fluidized beds. In this study, we propose a mechanically simple and thermally durable flow control system that combines an orifice for stepwise flow adjustment and a J-valve (loop seal) for on/off particle transport. In this study, the flow characteristics of the orifice, the minimum fluidization velocity (umf≈ 0.076 m/s), the transient stabilization behavior, and the effects of downstream pressure (back pressure) were evaluated in lab-scale experiments. The results showed that particle flow rate follows a power-law relationship with the orifice diameter, stabilizes when fluidization velocity exceeds umf, and decreases linearly with increasing back pressure. Based on these findings, we established design guidelines incorporating orifice sizing, fluidization control, and back pressure compensation.

Under the influence of engineering disturbances, the loading rate of surrounding rock is in a state of continuous adjustment. This study conducts experimental investigations on the mechanical response characteristics under different strain rates (10−5 s−1, 10−4 s−1, and 10−3 s−1). During the uniaxial loading process of coal–rock composite specimens, multi-parameter monitoring was implemented, and a systematic study was carried out on the ring-down count induced by microcracks, the energy values of acoustic emission (AE) events, the stage-dependent strain characteristics on the specimen surface, and the surface temperature variation characteristics. Additionally, the stress–strain curve characteristics under different strain rates were comparatively analyzed in stages. The loading process of the coal–rock composite specimens was reproduced using the Particle Flow Code (PFC3D 6.0) simulation software. The simulation results indicate that the stress–strain results obtained from the simulation are in good agreement with the laboratory test results; based on these simulation results, the energy accumulation and dissipation characteristics of the coal–rock composite specimens under the influence of strain rate were revealed. Furthermore, a microscopic damage model considering strain rate was constructed based on the Weibull probability statistics theory. The results show that strain rate has a significant impact on the strength, elastic modulus, and failure mode of the coal–rock composite specimens. At low strain rates, the specimens exhibit obvious progressive failure characteristics and strain localization phenomena, while at higher strain rates, they show brittle sudden failure characteristics. Meanwhile, the thermal imaging results reveal that at high strain rates, the overall temperature rise in the composite specimens is rapid, whereas at low strain rates, the overall temperature rise is slow—but the temperature rise in the coal portion is faster than that in the rock portion. The peak temperature at high strain rates is approximately 2 °C higher than that at low strain rates. The PFC simulation results demonstrate that the larger the strain rate, the faster the growth rate of plastic energy in the post-peak stage and the faster the release rate of elastic energy.

Influence of screw element geometry on particle flow in twin screw granulation: A DEM study

Assessment of behavioural modification techniques on particle-laden turbulent pipe flows

This study examines the charge reduction characteristics of charged particles using a neutralizer to prevent accidents from electrostatic discharge and enhance process efficiency. The research measures the number of charges, elimination efficiency, and penetration rate under various voltage polarity conditions with a DC-type bipolar electrostatic eliminator. The results indicate that electrostatic neutralization is most effective under negative high voltage (-HV) conditions, while the mesh penetration rate increases and charge accumulation occurs under positive high voltage (+HV) conditions. Furthermore, partial charge neutralization is observed under both positive and negative high voltage (±HV) conditions due to the sequential emission of positive and negative ions. This study quantifies the mitigation of electrostatic charge using a neutralizer, offering insights for optimizing filtration systems and improving process stability. Future research will refine electrostatic control mechanisms by considering additional parameters such as particle size, material properties, and flow conditions.

Controlling particle-laden flow in a ventilated trapezoidal chamber via surrogate-based multi-objective optimization