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The feeding shoe, which is a critical component that connects the rotary valve to the conveying pipeline, significantly influences the performance of powder conveying systems. The Computational Fluid Dynamics–Discrete Element Method (CFD-DEM) was employed to investigate particle dynamics within various feeding shoe designs under gas–solid two-phase flow conditions. Through comparative analyses of two-phase flow characteristics and particle trajectories, three feeding shoe configurations, namely, through, horn, and funnel types, were evaluated, along with the effects of varying gas velocities. Key structural parameters, including opening diameter and inclination angle, were systematically examined to assess their effect on particle transport efficiency. Results demonstrated that feeding shoes with a low inclination angle or a small opening diameter exhibited poor particle flow, while those with a large opening diameter tended to induce backflow on the left side. By contrast, through-type feeding shoes with a large inclination angle and equal opening diameter achieved optimal conveying performance, minimizing backflow and enhancing flow efficiency. These findings provide theoretical insights for optimizing feeding shoe designs, improving conveying efficiency, and reducing production costs, offering valuable guidance for advancements in powder conveying technology and fluid mechanics.

The article presents an experimental laboratory setup used for the empirical determination of the gasification of coal samples in the form of solid rock, cut out in the form of a cylinder. An experimental laboratory set enabled a series of experiments carried out at 700 °C with steam as the gasification agent. The samples were prepared from the coal seam, the use of which can be planned in future underground and ground gasification experiments. The result of the conducted coal gasification process, using steam as the gasification agent, was the syngas, including hydrogen (H2) with a concentration between 46% and 58%, carbon dioxide (CO2) with a concentration between 13% and 17%, carbon monoxide (CO) with a concentration between 7% and 11.5%, and methane(CH4) with a concentration between 9.6% and 20.1%.The results from the ex-situ experiments were compared with the results of numerical simulations using computational fluid dynamics (CFD) methods. A three-dimensional numerical model for the coal gasification process was developed using Ansys-Fluent software to simulate an ex-situ allothermal coal gasification experiment using low-moisture content hard coal under atmospheric conditions. In the numerical model, the mass exchange (flow of the gasification agent), the turbulence description model, heat exchange, the method of simulating the chemical reactions, and the method of mapping the porosity medium were included. Using the construction data of an experimental laboratory set, a numerical model was developed and its discretization (development of a numerical grid, based on which calculations are made) was carried out. Tip on the reactor, supply method, and parameters maintained during the gasification process were used to define the numerical model in the Ansys-Fluent code. A part of the data were supplemented on the basis of literature sources. Where necessary, the literature parameters were converted to the conditions corresponding to the experiment, which were carried out. After performing the calculations, the obtained results were compared with the available experimental data. The experimental and the simulated results were in good agreement, showing a similar tendency.

The discrete element method (DEM) and the moving particle semi-implicit (MPS) method are the most popular mesh-free particle methods in the discontinuum and continuum. This paper describes a state-of-the-art modeling on multi-phase flows using these mesh-free particle methods. Herein, a combinational model of the signed distance function (SDF) and immersed boundary method (IBM) is introduced for an arbitrary-shaped wall boundary in the DEM simulation. Practically, this model uses a simple operation to create the wall boundary. Although the SDF is a scalar field for the wall boundary of the DEM, it is useful for the wall boundary of the CFD through combination with the IBM. Validation tests are carried out to demonstrate the adequacy of the SDF/IBM wall boundary model. Regarding the mesh-free particle method for continuum, the phase change problem is one of the challenging topics, as the solid state is usually modeled by extremely high viscous fluid in the phase change simulation. The phase change simulation is shown to be efficiently performed through an implicit algorithm and a heat flux model in the MPS method. The adequacy of these models is verified by the numerical examples.

This study develops a coupled computational fluid dynamics (CFD) and discrete element method (DEM) two-phase flow model to investigate particle deposition behaviors in industrial pipeline transportation of edible chili oil, a high-viscosity fluid widely used in food industries. Due to its complex rheological properties and the presence of suspended solids, chili oil pipelines frequently face significant challenges, including excessive particle deposition at pipe bends, increased pressure drops, and energy inefficiency. To address these critical issues, simulations were systematically conducted using the Realizable k-ε turbulence model, examining the effects of different inlet velocities (0.5–2.5 m/s), particle sizes (2–4 mm), and particle shapes (spherical, rod-shaped, and cubic). Results showed that operating the pipeline within an optimal transport velocity range of approximately 1.0–1.5 m/s effectively minimized particle accumulation at bends and significantly reduced pressure losses. Quantitatively, spherical particles exhibited the lowest pressure drop increase (from approximately 3.45 kPa at 0.5 m/s to 21.78 kPa at 2.5 m/s) due to reduced collision frequencies and kinetic energy dissipation. In contrast, irregular particles (cubic shapes) led to the highest pressure drops, rising sharply from 5.91 kPa at 0.5 m/s up to 34.56 kPa at 2.5 m/s, caused by frequent collisions and turbulent fluctuations. Additionally, simulations revealed that increasing particle size from 2 to 4 mm notably decreased particle deposition and pressure losses due to reduced collision frequency and enhanced momentum transfer. These quantitative findings not only fill the research gap concerning high-viscosity, particulate-laden edible fluid systems but also provide concrete and practical guidelines for optimizing chili oil transport processes. The findings directly contribute to improved operational reliability, lower energy consumption, and reduced blockage risks in industrial food pipeline applications.

Heavy-duty vehicle (HDV) platooning, facilitated by vehicle-to-vehicle communication, plays a crucial role in transforming logistics and transportation. It reduces fuel consumption and emissions while enhancing road safety, supporting sustainable freight strategies and the integration of autonomous vehicles. This study employs a hybrid approach combining wind tunnel experiments and Computational Fluid Dynamics (CFD) simulations to analyze HDV platoon aerodynamics. The approach has two sequential phases: single-HDV simulation validation and multi-HDV platooning simulation. In the first phase, a single HDV CFD simulation is validated against NASA’s benchmarks, with optimized mesh generation, proper models, and conditions, and errors minimized below 1%. In the second phase, the validated model is used for multi-HDV platooning simulations, maintaining consistent mesh structures, physical models, and boundary conditions. Various platoon configurations are explored to assess the effects of speed, inter-vehicle spacing, and platoon size and position on aerodynamic drag, with virtual wind tunnel simulations evaluating drag coefficients. Our findings reveal that inter-vehicle spacing critically influences drag. An optimal range of 0.25 to 0.5-times the HDV length is identified to achieve an effective balance between safety and fuel efficiency, reducing platoon aerodynamic drag by 13–44% compared to single HDVs. While platoon speed is generally limited to impacting drag, it becomes more pronounced when an HDV platoon has very small inter-vehicle spacings, or in platoons exceeding five HDVs. Moreover, as the platoon size increases, the overall aerodynamic drag coefficient diminishes, particularly benefiting the rear HDV in larger platoons with smaller inter-vehicle spacing. These insights offer a comprehensive understanding of HDV platoon aerodynamics, enabling logistics enterprises to optimize platoon configurations for fuel savings, improved traffic flow, larger platoon formation, and enhanced transportation safety.

Thermal stress of the rotor in a squirrel cage induction motor is generated due to the temperature rise, it is also one of the factors causing the broken bar fault because the structure of the rotor would be destroyed if the stress of the rotor bars exceed the strength limit. The coupled fluid-thermal analysis for the induction motor with healthy and broken bar rotors is performed in this paper. Much concern has been committed to establishment of the fluid model on the basis of computational fluid dynamic (CFD) theory. The heat field of the prototypes is analysed so that the effect of the asymmetrical rotor on the motor heat performance can be investigated in depth. Eventually, the efficiency of the presented model and method, for the totally enclosed fan cooled (TEFC) induction motor, can be verified through experimental results. In addition, this paper reports a quantitative analysis of the heat flux distribution of the fault rotor, and the heat flux density of the bars is investigated in detail. Then, the part most likely to break in the rotor as a result of the thermal load is identified.

The objective of this article is to address the challenges associated with visualizing air flow over a heating source in an open laboratory environment. The study uses a combination of experimental visualization and numerical simulation techniques to generate a 3D model of the air flow and heat transfer between the heating source and the environment via natural convection. The Particle Image Velocimetry method is used to experimentally visualize the air flow, which is known for its benefits of high speed and accuracy, and for its ability to avoid disturbing the flow of the fluid being investigated. The data obtained from this experimental method are used as input for numerical simulations using the Ansys Fluent program. The numerical simulations identify air vortices and other elements that disrupt the airflow in the laboratory environment. The resulting 3D model accurately represents the actual situation in the laboratory and could be further optimized by adjusting parameters such as the output of the heater and the heating source temperature. These parameters play a crucial role in ensuring thermal comfort in the laboratory environment, which is of utmost importance for user comfort. In conclusion, the study provides valuable insights into the visualization of air flow over a heating source and demonstrates the effectiveness of combining experimental and numerical simulation techniques to generate accurate 3D models of air flow and heat transfer.

Hydrogen energy is vital for a clean, low-carbon society, and proton exchange membrane fuel cells (PEMFCs) represent a core technology for the conversion of hydrogen chemical energy into electrical energy. When PEMFC single cells are stacked under assembly force for high power output, their porous electrodes (gas diffusion layers, GDLs; catalyst layers, CLs) undergo compressive deformation, altering internal transport processes and affecting cell performance. However, existing microscale studies on PEMFC porous electrodes insufficiently consider compression (especially in CLs) and have limitations in obtaining compressed microstructures. This study proposes a combined framework from a microstructure perspective. It integrates the finite element method (FEM) with computational fluid dynamics (CFD). It reconstructs microstructures of GDL, CL, and GDL-bipolar plate (BP) interface. FEM simulates elastic compressive deformation, and CFD calculates transport properties (solid zone: heat/charge conduction via Laplace equation; fluid zone: gas diffusion/liquid permeation via Fick’s/Darcy’s law). Validation shows simulated stress–strain curves and transport coefficients match experimental data. Under 2.5 MPa, GDL’s gas diffusivity drops 16.5%, permeability 58.8%, while conductivity rises 2.9-fold; CL compaction increases gas resistance but facilitates electron/proton conduction. This framework effectively investigates compression-induced transport property changes in PEMFC porous electrodes.

The objective of this study is to create a simulation of a cavity containing high-heat rack server computing equipment. The aim is to explore various numbers of openings (two and four apertures) and rack layouts (shelf spacing of 30 and 60 mm and shelf height spacing of 35 and 17 mm) in order to minimize indoor temperature and achieve optimal heat dissipation. The numerical results are evaluated against the experimental data through the utilization of the least squares approach to determine unknown physical quantities. Next, a turbulence model that is appropriate is chosen using root mean square error analysis. The zero-equation model was selected for scenarios involving four ventilation openings, whereas the RNG k-ε model was good for scenarios involving two openings. Then, the resulting temperature and flow fields are assessed thereafter. Results revealed that expanding the distance between two racks has a minimal impact on the temperature of the rack surface and the convection coefficients. Thus, this research suggested using a shelf arrangement with a 30 mm shelf spacing to mitigate the occurrence of localized eddy currents at the upper part of the cavity, potentially diminishing the efficiency of ventilation. The presence of openings at the bottom of the cavity led to a 42% improvement in convection heat transfer coefficients, compared to cases without such apertures. Hence, it was recommended to incorporate apertures at the lower part of the cavity to facilitate the intake of cold air. Furthermore, reducing the shelf height spacing resulted in an increase in temperature of around 2 K on the surface of the rack. Nevertheless, it was deemed suitable for optimizing space utilization.

In this article, the calm water resistance and dynamic instabilities of a semi-displacement catamaran fitted with a stern wedge is investigated using an experimental method and numerical technique. This is accomplished in order to probe into the effects of aft geometry modification on semi-displacement ship dynamic characteristics, especially at medium and high speeds. An advanced 6-DOF model that takes into consideration the dynamic mesh method has been utilized in open source code OpenFOAM. Reynolds-Average Navier-Stokes (RANS) equations are solved using standard k-ε turbulence model and VOF method. The accuracy of the current numerical method is investigated by the calm water test in National Persian Gulf Towing Tank. The resistance, trim and sinkage of the ship were monitored during the experiments. The experimental analysis was performed on the initial model and a modified model with 8º wedge at different Froude numbers. After that, the wedges were mounted at different angles at the transom of the vessel and the effect of the angle change for 4 different angles was evaluated using numerical solution. The results show that fitting a stern wedge to this type of ship causes an intense pressure at the stern bottom. Also, it decreases the dynamic trimming and forward resistance of the craft. As well as, stern wedge causes increasing the lift force which affects the reduction of dynamic instabilities. It is concluded that numerical model presented here is quite suitable for accurately predicting dynamic characteristics of a semi-planing twin-hull ships at medium and high Froude numbers. As a result, 14% reduction in total resistance was observed due to the installation of a 6 degree stern wedge.