Three-dimensional Simulation Model Research Articles

The generation method of orthophoto expansion map of arched dome mural based on three-dimensional fine color model

Murals carry cultural significance and historical information, and are an important channel for understanding ancient social norms, artistic styles, and religious beliefs. At present, the digitization of murals is an important technical means for the protection of cultural heritage. Orthogonal images of murals play a vital role in high-precision recording, preservation, academic research, educational expansion, mural protection, digital exhibition and dissemination. At present, orthogonal images of murals are mostly realized by plane projection, but this method is not suitable for making orthogonal images of arched and dome-shaped murals. To address this problem, this paper proposes a method for generating orthogonal expansion images of arched and dome-shaped murals. This method combines a three-dimensional virtual space simulation model with an RTT virtual camera and adopts a spatial reference orthogonal ray scanning model. First, the detailed three-dimensional color model is fitted to the geometric reference of cylindrical and spherical objects to determine its parameters. Next, for the cylindrical murals on the arch, the orientation of the model is initialized using quaternions, and the viewport matrix is adjusted to obtain the required resolution. Then, the RTT camera is used to perform line orthogonal projection in the viewport, and the fringe projection image is generated by rotating around the cylinder axis according to the inversely calculated rotation angle. For the murals on the dome ceiling, this method is used to segment them according to a certain longitude, and the circumscribed cylinder of the fitted sphere is rotated to perform cylindrical orthogonal line scanning in the segmented area. These individual orthogonal line scan images are carefully spliced together to form a complete orthogonal unfolded image. Finally, a fringe projection image is generated with the central meridian of the unfolded part as the center line, and the fringe projection images are spliced together to obtain the final orthogonal unfolded image. Experiments show that compared with existing methods, this method can generate two-dimensional orthogonal unfolded images with high texture fidelity, minimal texture deformation, and uniform deformation distribution. This study provides a novel perspective on the orthogonal unfolding of quasi-cylindrical and quasi-spherical painted objects, and provides an accurate and diverse data basis for the digitization of murals.

Structural Design and Optimization of Proton Exchange Membrane Fuel Cell Ejector

Proton exchange membrane fuel cells (PEMFCs) produce electrical energy using hydrogen as an energy source, characterized by enhanced energy conversion efficiency and diminished emissions, contributing to the sustainable development of energy. The hydrogen ejector is essential for improving the hydrogen utilization efficiency in PEMFCs. In this study, the theoretical design and simulation optimization of a hydrogen ejector used for a hydrogen fuel cell are performed in order to improve the efficiency of the hydrogen ejector. According to Sokolov’s design method, the dimensions of the ejector nozzle and mixing chamber were calculated. A three-dimensional fluid simulation model of the ejector was established, and the accuracy of the model was verified by the experimental results. The influences of the nozzle outlet distance, the mixing chamber diameter, the length–diameter ratio of the mixing chamber, and the nozzle curvature on the ejector ratio were studied under multiple working conditions, and the optimal structural size of the ejector was obtained to satisfy the working conditions. It was found that the maximum ejector ratio of 1.21 could be achieved at a nozzle exit distance of 9 mm, a mixing chamber diameter of 7 mm, a mixing chamber length–diameter ratio of 9, and a nozzle curvature of 0.02. This work can provide some insights into the relationship between the structural parameters and performance of hydrogen ejectors.

A Study on the Attenuation Patterns of Underground Blasting Vibration and Their Impact on Nearby Tunnels

The natural caving method, as a new technique in underground mining, has been promoted and applied in several countries worldwide. The destruction of the bottom rock mass structure directly impacts the structural stability of underground engineering, resulting in damage and collapse of underground tunnels. Therefore, based on the principles of explosion theory and field monitoring data, a scaled three-dimensional numerical simulation model of underground blasting was constructed using LS-DYNA19.0 software to investigate the attenuation patterns of underground blasting vibrations and their impact on nearby tunnels. The results show that the relative error range between the simulated blasting vibration velocities based on the FEM-SPH (Finite Element Method–Smoothed Particle Hydrodynamics) algorithm and the measured values is between 7.75% and 9.85%, validating the feasibility of this method. Significant fluctuations in blasting vibration velocities occur when the blast center increases to within a range of 10–20 m. As the blast center distance exceeds 25 m, the vibration velocities are increasingly influenced by the surrounding stress. Additionally, greater stress results in higher blasting vibration velocities and stress wave intensities. Fitting the blasting vibration velocities of various measurement points using the Sadovsky formula yields fitting correlation coefficients ranging between 0.92 and 0.97, enabling the prediction of on-site blasting vibration velocities based on research findings. Changes in propagation paths lead to localized fluctuations in the numerical values of stress waves. These research findings are crucial for a deeper understanding of underground blasting vibration patterns and for enhancing blasting safety.

Effect of injection strategy on spray and combustion processes in 2-stroke rod-less opposed piston engine (2S-ROPE)

The 2-stroke Rod-less Opposed Piston Engine (2S-ROPE) is a novel engine design that has garnered attention owing to its high power and low fuel consumption. This study investigated the effects of different fuel injection strategies on the in-cylinder working process of a 2S-ROPE engine, which features a smaller combustion space and lateral injection than conventional diesel engines. A high-precision three-dimensional simulation model was developed to examine the fuel atomization and in-cylinder combustion processes under four distinct injection strategies (S1, S2, S3, and S4). The results demonstrated that the injection strategy significantly influenced the number of oil droplets, particularly for small particles. The number of small droplets in S4 was approximately 6 times that in S1. The double-layer injection strategies (S3 and S4) exhibited a better atomization breakup and oil-air mixing, leading to a faster combustion rate and higher lift power than the single-layer injection strategies (S1 and S2). These findings suggest that the double-layer injection strategy is more suitable for a 2S-ROPE engine, increasing the lift power by up to 23 %. The results can guide the improvement of combustion parameters in most opposed piston engines.

Numerical simulation and intelligent prediction of a 500 t/d municipal solid waste incinerator

After classifying municipal solid waste (MSW), understanding how changes in its characteristics affect the incineration process becomes essential. Optimizing and adjusting operating parameters is crucial to ensure the smooth operation of MSW incinerators. In this study, we developed a three-dimensional numerical simulation model for a 500 t/d MSW incinerator, based on a two-fluid model that accounts for grate motion. We examined the effects of load and moisture on the combustion process. Using the results from the numerical simulation and on-site operational data, we established a machine learning model to predict incinerator conditions based on load, waste particle size, and moisture content. The average relative errors for the training and test sets were approximately 0.33 % and 0.44 %, respectively. Finally, we compared the influence of different operating parameters on flue gas temperature. Our numerical simulation model and intelligent prediction method offer valuable guidance for optimizing existing MSW incinerators and designing new ones.

Equivalent Simulation Study of Delta-Rotor Engine

The mechanical structure, movement mode, and combustion process of a triangular rotor engine differ from those of a conventional engine with a crank connecting rod mechanism as the core. This makes it impossible to directly use existing simulation software to simulate the performance of the entire engine, rendering it difficult to conduct structural evaluation and performance prediction during the engine development stage. Therefore, using existing performance simulation software to establish a performance-equivalent model for a triangular rotor engine is crucial. To solve the above problems, this study proposes a performance-equivalent simulation modelling method for a triangular rotor engine based on a three-dimensional simulation model and the operating principles of the triangular rotor and four-stroke engines. Compared to various performance indicators obtained from the three-dimensional simulation model, the results show that the equivalent model established in this study has sufficient accuracy for key indicators such as the cylinder pressure, cylinder temperature, and in-cylinder quality under various working conditions. This can satisfy the requirements of the complete machine-performance simulation of a triangular rotor engine.

Rapid simulation of knitted fabrics based on a ribbon yarn model

In the study, an innovative three-dimensional ribbon-based yarn model simulation technique is introduced, aimed at significantly enhancing the realism and speed of knitted fabric simulation through efficient model construction and rendering processes. The method successfully overcomes the limitations of traditional two-dimensional loop models and tubular yarn models, accurately capturing the textural details of knitted fabrics with a vivid three-dimensional representation. Experimental results demonstrate the outstanding performance of this simulation system in simulating the fuzz effects of yarn and in processing speed. This technology offers significant potential in textile design and production, notably in boosting design efficiency and accelerating new product development. By employing low-cost image capture methods, the study effectively reduces technical and financial barriers in knitted fabric simulation, enhancing its practical and industrial applicability.

Research on the Dynamic Leaking and Diffusion Law of Hydrogen-Blended Natural Gas under the Soil–Atmosphere Coupled Model

With the breakthrough in mixing hydrogen into natural gas pipelines for urban use, the widespread application of hydrogen-blended natural gas (HBNG) in energy delivery is imminent. However, this development also introduces significant safety concerns due to notable disparities in the physical and chemical properties between methane and hydrogen, heightening the risks associated with gas leaks. Current models that simulate the diffusion of leaked HBNG from buried pipelines into the atmosphere often employ fixed average leakage rates, which do not accurately represent the dynamic nature of gas leakage and diffusion. This study uses computational fluid dynamics (CFD) 2024R1 software to build a three-dimensional simulation model under a soil–atmosphere coupling model for HBNG leakage and diffusion. The findings reveal that, in the soil–atmosphere coupling model, the gas diffusion range under a fixed leakage rate is smaller than that under a dynamic leakage rate. Under the same influencing factors in calm wind conditions, the gas primarily diffuses in the vertical direction, whereas under the same influencing factors in windy conditions, the gas mainly diffuses in the horizontal direction.

Using three turbulence simulation methods for modeling the flying of high-speed railway tunnel lining blocks under piston airflow

The detached tunnel lining concrete blocks poses a serious threat to the safety of moving high-speed train. Understanding the flight characteristics of detached blocks from the tunnel soffit under train piston airflow is essential for devising appropriate measures to mitigate such risks during train operation. Computational Fluid Dynamics (CFD) simulation methods, known for their high efficiency and good repeatability, are effective approaches to study this subject. Large Eddy Simulation (LES), Improved Delayed Detached Eddy Simulation (IDDES), and Unsteady Reynolds-Averaged Navier-Stokes (URANS) are three commonly used turbulence simulation methods in the CFD simulation of train/tunnel aerodynamics. In this study, a three-dimensional CFD simulation model based on the three turbulence simulation methods is established for the airflow-tunnel-train-detached block system, and an experiment is conducted for validating the CFD model. Using the established models, the influence of different turbulence simulation methods on the flight trajectory and aerodynamic coefficients of detached lining blocks under train-induced airflows is compared. By visualizing the macroscopic flow field inside the tunnel and the local flow field near the detached block, the flow mechanisms of detached blocks under different turbulence simulation method conditions are revealed. The results showed that in the 1st stage (BTT stage), the flight of the detached block is influenced by the airflow near the train body, while in the 2nd stage (ATT stage), it is mainly affected by the train wake vortex. Compared with experimental results, the errors of LES and IDDES in simulating the longitudinal direction displacement of the block are only 2.3 % and 5.5 %, respectively, while the error of URANS is 10.6 %. The simulation error of URANS for the longitudinal direction flight speed reached 8.8 % in the ATT stage. In the BTT stage, LES and IDDES predicates more and larger leeward side vortex structures of the detached block, while URANS predicates fewer and smaller vortex structures. Compared with URANS method, the dissipation rate of the vortex structures simulated by LES and IDDES in the ATT stage is slower. These are the main reasons explaining why the flight characteristics of detached lining blocks obtained by URANS method are different from the LES and IDDES methods.

Noise reduction design of new residential buildings along urban roads-taking a residential district in Foshan as an example

Taking a residential district in Foshan along the city road as an example, the impact of urban road traffic noise on it is studied. Firstly, the data is monitored in the noise field, then three-dimensional simulation models of residential buildings and road distribution are established in Cadna/A software, and noise simulation prediction is carried out according to the actual situation and relevant norms and standards. The predicted noise values of the exterior surface of residential buildings are obtained, which has exceeded the permissible interior noise level for residential buildings. By comparing the application effects of noise reduction measures in buildings, the noise reduction design scheme of new residential buildings along urban roads is finally proposed: the sound insulation doors and windows that meet the requirements are adopted. After the completion of the house, the indoor background noise and the sound insulation performance of the doors and windows are measured. The measured results show that the selection of sound insulation doors and windows is suitable and the indoor noise environment meets the design requirements of noise reduction. The results are helpful to provide technical reference for the noise reduction design and renovation of other residential buildings along urban roads.

Design of innovative phase-change cold storage refrigerator and simulation analysis of discharging progress

At present, the field of cold chain logistics experiences significant growth, with refrigerator playing a pivotal role in cold chain transportation. An innovative compartmentalized phase-change cold storage refrigerator has been proposed in this study, designed to address the increasing demand for efficient and energy-saving solutions in the cold chain transportation industry. A conceptual module prototype is designed and built in this study, with an analysis of the system's charging and discharging processes under varying conditions. The cold storage refrigerator exhibits favorable matching characteristics, the charging process requires approximately 270 min, and the cooling effect sustains for about 23 h. A three-dimensional simulation model of the cold storage refrigerator is developed, enabling a comprehensive evaluation of the cooling effect and further optimization of the cold storage plate layout. The results indicate that the layout of the three-sided type cold plate significantly reduces the pre-cooling time. It is determined through simulation calculations in this study that setting the loading capacity to 50 % can strike a balance between efficient cooling and transportation efficiency. Additionally, under high-temperature conditions, the cold storage refrigerator maintains a low temperature for up to 10 h at a filling rate of 50 %.

Thermodynamic performance and compression characteristics analysis of low GWP refrigerant in compressors: Experimental investigation and 0-D/3-D simulation

The utilization of low global warming potential (GWP) refrigerants is crucial for reducing greenhouse gas emissions. Among these alternatives for hydrofluorocarbons (HFCs), R290 stands out as a natural refrigerant with a low GWP value of 3. Therefore, it is beneficial to promote its widespread adoption and enhance the efficiency of compressors and their systems that utilize R290 to mitigate the greenhouse effect. The present study investigates and compares the thermodynamic performance and compression characteristics of a high-speed compressor employing R290 as a refrigerant with those of an R32 compressor. In contrast to previous studies, this paper presents a novel approach by developing validated the zero-dimensional (0-D) and three-dimensional (3-D) simulation model, along with experiments, to investigate the distribution of performance loss and suction-compression characteristics in high-speed R290 compressors. The results demonstrate that the R290 compressor exhibits superior volumetric efficiency, while excessive compression at high speeds leads to a noticeable reduction in indicated power. The combination of increased over-compression loss and motor loss at high speeds resulted in a 11.7% rise in input power, leading to an 8.4% decline in thermodynamic performance for the R290 compressor under standard heating compared to the R32 compressor.

A meshless model for three-dimensional direct numerical simulation of local scour around cylinder bridge foundation

A meshless local scour model for cylinder bridge foundation based on the smoothed particle hydrodynamics (SPH) method is proposed in this paper. Differing from the traditional Eulerian mesh model used for monopile local scour, it overcomes the high requirements of mesh quality and density for capturing large deformations at the fluid interface. Unlike the transient sediment erosion SPH model used for dam-break, sediment flushing, and water jet, the meshless approach is innovatively applied to the continuous simulation of bridge local scour under steady flow conditions. The present SPH model is established based on the SPH multi-phase fluid model, integrating a classical fluid model combined with numerical stabilization algorithms to govern water particle motion and a sediment model from Zhang et al. (2024) to govern sediment evolution, and tests a new scheme for boundary treatment in the model based on DualSPHysics. Furthermore, a novel scour visualization method that aims at extracting both visible and actual bed surfaces from discrete particles is proposed. The model is validated through comparison with rigid bed and live bed experiments, demonstrating favorable agreement in terms of flow and scour simulation. Importantly, the model results reveal a discrepancy between the elevation of the post-scour visible bed surface derived from the conventional Eulerian mesh model and experimental data, compared to the actual bed surface unaffected by water flow erosion. This indicates the necessity for incorporating a safety margin in foundation design when utilizing experimental results to determine the maximum scour depth.

Modeling and 3-D simulation of petroleum coke calcination process: investigation of the effect of main operating variables

Abstract Coke calcination is a process that involves heating green petroleum coke to purify it and eliminate volatile materials for subsequent processing. Due to the complexity of the rotary kiln used in this process, conducting experimental studies can be challenging and restricted. However, quantitative analyses based on developed models can provide a foundation for optimizing and controlling the process, which can significantly enhance the design efficiency. A three-dimensional simulation model of a rotary calcining kiln for petroleum coke was created using COMSOL Multiphysics in a steady-state mode. This model accounted for all relevant physical and chemical phenomena in the gas stream and coke bed flow, including heat transfer, combustion, and the evolution of volatile matter and coke dust. The mathematical modeling yielded distributions of temperature and mass fractions within the kiln, as well as the velocity field. The results revealed two distinct peak temperatures in the gas phase: 1,780 K near the primary air injection point and 1,605 K near the tertiary air injection points. The findings were analyzed, and the impact of key variables was explored. The simulation data indicated that for every decrease of 10–15 m/s in air flow, the gas peak temperature dropped by approximately 100°. Additionally, an increase in the input oxygen concentration led to enhanced combustion, resulting in higher peak concentrations of CO2. The developed simulation model has proven to be a valuable and promising tool for the design and optimization of petroleum coke rotary kilns.

Identification and Application of Wave Field Characteristics of Channel Waves in Extra-Thick Coal Seams

Channel wave seismic activity often occurs with thin and medium-thick coal seams being the main target layer. To address the problem of channel wave applicability detection in extremely thick coal seams, the propagation and identification characteristics of channel waves remain the focus of research. Therefore, this paper takes the in-seam wave exploration of a 27 m extremely thick coal seam as an example and uses the staggered mesh finite difference method to construct a three-dimensional medium model for numerical simulation. An analysis of the physical parameters of coal and rock, along with the dispersion characteristics of channel waves in extra-thick coal seams, is utilized, through the Zoeppritz equation and the total reflection propagation method, to calculate the imaging. We found the following: (1) The dispersion areas and weak dispersion areas along the detection direction are extremely thick coal seams. (2) There are apparent channel waves in extra-thick coal seams, with a waveform similar to body waves; the length of the wave train is shorter than that of the conventional channel wave, and the arrival time can be estimated accurately. The amplitude of the apparent channel wave is affected by the degree of dispersion, with lower attenuation and higher resolution. The characteristic of total reflection in extremely thick coal seams is that the incident angle is equal to the critical angle, and the dispersion characteristics are weak. (3) The channel waves with weak dispersion characteristics in extra-thick coal seams are mainly Love-type waves.

Large-Scale Physical Simulation Experiment of Water Invasion Law for Multi-Well Development in Sandstone Gas Reservoirs with Strong Water Drive

In order to clarify the water invasion law and residual gas distribution characteristics in edge and bottom water gas reservoirs with multi-well development, a large-scale three-dimensional physical simulation model was developed and a physical simulation experiment method for the water invasion law of multi-well development in sandstone gas reservoirs with strong water drives was established. Water invasion physical simulation experiments of multi-well development under the conditions of different water body multiples and production systems were conducted. The results show the following: (1) Gas wells near fractures and high-permeability zones experience the earliest water breakthrough. The larger the water body multiple, the faster the rate of water invasion, the earlier the water breakthrough time of gas wells, the more severe the degree of water invasion in gas reservoirs, and the lower the ultimate recovery rate. (2) Shutting in low-position gas wells immediately after water breakthrough reduces the overall water production of the gas reservoir and extends the overall water-free gas production period. However, the ultimate recovery rate is lower than when the wells are not shut in. (3) The residual gas in the fracture model is mainly distributed around the fracture and the edge of the gas reservoir, with the ultimate recovery rate ranging from 38.5% to 58.2%. The residual gas in the fracture–high-permeability zone model is mainly distributed around the fracture–high-permeability zone and the edge of the gas reservoir, with the ultimate recovery rate ranging from 28.32% to 41.8%. The experimental results have important guiding significance for the economical and efficient development of similar gas reservoirs.

Study of the Impact of Surface Topography on Wear Resistance

The surface texture parameter is a real reflection of the surface topography, which is closely related to the tribological properties of the surface, and the study of the correlation between the surface texture parameter and wear resistance is of great significance in revealing the tribological influence mechanism of the surface and realising the functional manufacturing of the surface. This paper takes the ball-end milling surface as the research object, establishes the three-dimensional simulation model of the surface topography, and analyses the surface topography and the surface texture parameter change rule. Based on the improved correlation analysis model, the correlation characteristics between the surface texture parameters, and between the surface texture parameters and the relative wear rate of per unit sliding distance KV, were investigated, and the prediction model of KV was established based on the surface texture parameters Sku, Sa, Sxp, Sp, and Ssk, and the correctness of the model was verified by experiments. The study in this paper provides a new idea to further reveal the relationship between surface topographical features and wear resistance and to guide the functional manufacturing of surfaces.

Gas Fire Coupling Control of Goaf Based on Numerical Simulation

ABSTRACT In response to the problem that traditional gas control methods such as water injection and inert gas fire extinguishing are not effective and have a high level of risk in goaf, this study uses COMSOL software to establish a three-dimensional numerical simulation model of goaf, and combines air leakage intensity, oxygen concentration, and floating coal thickness to calculate the gas fire hazard area, in order to achieve effective control. The results show that the deviation between the data obtained from the numerical simulation and the actual measurement value is about 7 m, which proves that the given solution is reliable. The gas concentration of the wind lane and the upper corner is controlled below 1%, which proves that this method ensures the safety of the working environment. The above results show that the design method realizes the effective control of gas fire in the goaf, and provides reference for mine safety management and gas disaster control.

A LiDAR-driven three-dimensional simulation model for far-red solar-induced chlorophyll fluorescence in forests

Solar-induced chlorophyll fluorescence (SIF) is a subtle but informative probe of plant photosynthesis. Quantifying the three-dimensional (3D) distribution of SIF benefits a better understanding of photosynthesis variations over heterogeneous canopies. Although radiative transfer models (RTMs) provide a solid theoretical basis for simulating the 3D SIF distribution, most RTMs use virtual scenes with complex reconstruction processes. This study aims to develop a 3D SIF simulation model (FluorLiDAR) directly driven by terrestrial light detection and ranging (LiDAR) data using leaf and canopy RTMs, including a 3D PAR (photosynthetically active radiation) simulation model, the Fluspect model, the atmosphere radiative transfer module in SCOPE, and the multiple scattering coefficients of sunlit and shaded leaves from the 4-scale model. The results show that (1) the simulated and measured SIF patterns were consistent, with R2 (RMSE) values of 0.73 (0.17 mW/nm/m2/sr) and 0.76 (0.12 mW/nm/m2/sr) for 1-min sampling and 10-min averages, respectively. Moreover, the R2 between FluorLiDAR and the DART simulation reached 0.94. The R2 of FluorLiDAR and DART were both higher than 1D mSCOPE using every 10-min sampling data. (2) Point density, denoted by average NPD (nearest point distance), influenced the performance of our model mainly when it was smaller than 0.1 m. Chlorophyll content had less influence on the model accuracy (R2 and rRMSE), and the bias between simulation and measurement decreased as chlorophyll content increased. (3) The simulated 3D SIF distribution pattern closely resembled PAR within the canopy. Besides, FluorLiDAR can simulate the hot spot effect like DART and mSCOPE though the effect was not as obvious as the other two models. This study highlights the potential of a LiDAR-driven SIF model for 3D SIF simulation over a heterogeneous canopy, which may benefit the understanding of the structural impacts on forest photosynthesis in real forest scenes.

Numerical investigations on electrolytic performance of proton exchange membrane electrolysis cell with parallel flow field

In this study, a three-dimensional simulation model of PEMEC with parallel flow field was established, the heat and mass transfer, electrochemical reactions were described to investigate the electrolytic performance. The distribution characteristics of temperature, liquid water and gas products in the electrolysis cell were obtained. The results show that during the operation of PEMEC system, the liquid water content decreases sequentially along the flow channel direction, while there is a significant temperature gradient in the flow direction of the electrolysis cell. The increase of the initial temperature can increase the current density of the electrolytic cell when the temperature increases from 60 ℃ to 80 ℃, the current density can be increases by 7.86 %, but it can also lead to the dehydration of PEMEC, resulting in thermal degradation of PEMEC, and further the reactivity and proton transfer performance were decreased. It is also found that the increase of liquid water inlet flow not only increased the reactant concentration, accelerated the chemical reaction rate, but also took away more heat generated by ohmic polarization as a coolant, which was conducive to the improvement of electrolytic performance. As the inlet flow rate increased from 1 mL/s to 3 mL/s, the current density at 2.4 V and 1.4 V can be increased by 3.66 % and 1.77 %, respectively, and the maximum temperature can be reduced by 7.4 K.