3D Numerical Model Research Articles

Evolution Mechanism of Blast Furnace Cooling Plate Slag‐Hanging Behavior with Different Cooling System Structure

Based on the 3D heat transfer numerical simulation model, the evolution mechanism of blast furnace cooling plate slag‐hanging behavior with different cooling system structures is analyzed. Cooling plate reduced by 20 mm will not affect its slag‐hanging behavior. Copper cooling plate is best suited for high heat load areas. The vertical spacing of cooling plate is extended by 200 mm, the uniformity of the slag layer decreases by 5%, and the temperature of cooling plate and refractory material increases by 11 and 50 °C. Cooling plate vertical spacing of 510 mm or less can ensure stable slag hanging in the blast furnace. When using a single refractory material, the average uniformity of the slag layer is 95%, 86%, and 79% for graphite brick, semigraphite brick, and sialon‐SiC brick, respectively. Si3N4‐SiC brick cannot operate properly in high heat load areas. The factory can consider setting 125 mm sialon‐SiC brick in the furnace; graphite brick is used outside the furnace lining. The slag layer is well distributed, and the average value of uniformity is about 90%. Even if the slag layer is fully dislodged, the hot surface temperature of the furnace lining is 785 °C, and it can be quickly reslag hanging.

Study on the impacts of injection parameters on knocking in HPDI natural gas engine at different combustion modes

Based on three-dimensional (3D) computational fluid dynamics (CFD) software, a 3D numerical model was constructed to investigate the effects of injection timing, pilot diesel energetic ratio (PDER), and angle between the central axis of the diesel jet and the horizontal direction (α) on combustion and knock in the natural gas mixing-limited combustion (NMLC) mode and natural gas slightly premixed combustion (NSPC) mode. The results indicate that advancing the start of injection of natural gas (NSOI) leads to a slight improvement in indicated thermal efficiency (ITE), but also an increase in peak cylinder pressure (Pmax) and maximum pressure rise rate (MPRR). In the NMLC mode, as the diesel and natural gas injection interval (IDN) decreases, the interference between the diesel and natural gas jets intensifies, ultimately leading to instability in the flame propagation process and increased fluctuations in cylinder pressure. At different NSOIs, when IDN is 0°CA, the maximum amplitude of pressure oscillations (MAPO) is the highest. When the PDER is increased from 5 % to 15 %, ITE increases by 7.1 %. Under different combustion modes, as α increases, ITE first increases and then decreases. However, the NSPC mode achieves a higher ITE, reaching up to 44.4 %.

Weakening characteristics of pile group foundations in clayey soil under vertical cyclic loading: Experimental and numerical investigation

Long-term cyclic loading can substantially reduce the bearing capacity of pile foundations, potentially compromising the structural integrity of offshore foundations. A small-scale model test system for vertical cyclic loading of pile foundations is independently designed. Model experiments and numerical simulations were conducted to investigate the weakening characteristics of four foundation types (i.e., slab foundation, single pile with cap, 2 × 2 pile group foundation, and 3 × 3 pile group foundation) in clayey soil under cyclic loading. The results of both methods demonstrate that 3 × 3 pile group foundations exhibit the greatest resistance to deformation, followed by 2 × 2 pile groups, single piles with a cap, and slab foundations under cyclic loading. Furthermore, a 3D numerical model was developed to simulate the real-world behavior of a pile group foundation for an offshore wind turbine. Results reveal that although the ultimate compressive bearing capacity decreases with higher cyclic loading levels, typical cyclic loads (0.1–0.2) encountered in practice do not greatly affect the long-term bearing capacity of the foundations. The proposed experimental and numerical simulation methods offer valuable insights into the weakening characteristics of pile group foundations under cyclic loading.

Numerical Groundwater Model to Assess the Fate of Nitrates in the Coastal Aquifer of Arborea (Sardinia, Italy)

The Arborea plain in Sardinia (Italy) is classified as a nitrate vulnerable zone (NVZ). In the present study, the individual work steps that are necessary to progress from the existing 3D hydrogeological model to a 3D numerical groundwater model using the interactive finite-element simulation system FEFLOW 7.4 are shown. The results of the transient flow model highlight the influence of the drainage network on the overall groundwater management: the total water volume drained by the ditches accounted for approximately 58% of the annual outflow volume. The numerical transport simulations conducted from 2012 to 2020 using hypothetical field-based nitrate input scenarios globally underestimated the high concentrations that were observed in the NVZ. However, as observed in the field, the computed nitrate concentrations in December 2020 still varied strongly in space, from several mg L−1 to several hundreds of mg L−1. The origin of these remaining local hotspots is not yet known. The modeling of rainfall fluctuations under the influence of climate change revealed a general long-term decline in the groundwater level of several tens of centimeters in the long term and, in conjunction with a zero-nitrate scenario, led to a significant decrease in nitrate pollution. Although hotspots were attenuated, the concentrations at several monitoring wells still exceeded the limit value of 50 mg L−1.

Analysis of thermal behavior and mass transport for manufacturing deep-small hole by ultra-high frequency induction-assisted laser wire deposition

Synchronous ultra-high frequency (UHF) induction-assisted laser deposition is an effective approach to tackle the extreme heat input and common defects that originate from laser direct deposition. The added auxiliary induction heat source can reduce the energy input of the laser heat source which guarantees the geometric integrity of the embedded tube and decreases temperature gradient. Meanwhile, the effective preheating of the induction heat source assures the metallurgical bonding among the substrate, deposited track and embedded tube. Experiments showed that the effective bonding can be formed among substrate-deposited track and deposited track-embedded tube under suitable combination parameters of the laser heat and induction heat. To gain insight into the hybrid deposition, a 3D numerical model coupled with multi-physical fields was established to explore the thermal process and flow behavior with assistance of induction heat. Results indicated that the electromagnetic force produced by induction coil promotes the flow velocity, which increases heat convection. Investigation on the induction heat parameter demonstrated that raising current intensity can accelerate the flow velocity from 0.07 m s-1 to 0.09 m s-1 while the maximum temperature of the molten pool declined from 2610 K to 2440 K owing to the reinforced heat convection. The experimental cross-section of the deposited tracks and the detected element distribution in transition areas are well tested against the numerical simulation results. The grain size in the top region of the deposited track is refined with increasing current intensity, which is experimentally and numerically verified by observed microstructure and G*R value. Meanwhile, the fabricated deposited track with average friction coefficient of 0.445 can be obtained when the laser and induction parameters are 1000 W and 400A, respectively.

Cooling effect and parameter analysis of applying heat insulation layer to tunnel regionalization in construction period based on geothermal level

The construction of high geothermal tunnels presents significant difficulties due to the abnormal rock temperature gradients, including designing a reasonable and cost-effective insulation layer as well as effective cooling measures. In this study, the rock temperature distribution, environmental temperature, and lining surface temperature of the tunnel during the construction period were analyzed through field surveys. A numerical simulation model considering ventilation and heat transfer dynamics was established based on the geothermal measurements and construction characteristics of this tunnel. After validating the 3D numerical model, the effects of installing heat insulation layers according to geothermal levels on the tunnel temperature field control were investigated. Additionally, the impacts of different insulation layer thermal conductivities (λi), ventilation air volume (Wa), and duct thermal conductivities (λd) were analyzed. The results indicate: (1) The comparison of temperature fields in tunnels with insulation layers, which is applied in the range of the rock temperature above 50 °C and without insulation layers was made. The temperature near the excavation face (TAm-1) decreases by up to 0.3% (0.5 °C), tunnel environment temperature with insulation layer applied (TAm-2) decreases by up to 4.2% (2.1 °C), the secondary lining temperature (TSec-lining) decreases by up to 10.5% (4.6 °C), and the wind temperature of air duct outlet (TAir-duct) decreases by up to 0.7% (0.5 °C). (2) The length of the insulation layer increases to the full length of the tunnel, TAm-1 continues to decline by only 0.4°C, TAm-2 by 0.5 °C, TSec-lining by 0.9 °C, and TAir-duct by 0.1 °C, which shows that it is the most economical and reasonable to apply the insulation layer only in the tunnel area where the rock temperature is higher than 50 °C. (3) As λi increases, both the tunnel environment and secondary lining temperatures exhibit linear increases, while increasing Wa and λi cause quadratic decreases and increases in tunnel temperature field parameters, respectively. (4) Range analysis of orthogonal experiments reveals that for tunnel temperature field impact level. For TAm-1, the significance order is Wa >λd >λi. And for TAm-2 and TSec-lining, the significance order is Wa >λi >λd, which can provide the more economical scheme for the insulation layer design and cooling schemes in the high ground temperature tunnel.

How a volcanic arc influences back-arc extension: insight from 2D numerical models

How a volcanic arc influences back-arc extension: insight from 2D numerical models

Disaster mechanism of large-diameter shield tunnel segments under multi-source load coupling: A case study

The deflection squeezing of the shield shell and the eccentric jack thrust significantly impact the segment dislocation and damage. Based on summarizing the derivative relationship between engineering factors and disasters, this study established a 3D numerical calculation model under the multi-source load coupling. Then, this study explored the displacement and dislocation distribution of segments, as well as their derivative relationship with bolt failure. Furthermore, this study analyzed the spatial distribution and evolution characteristics of segment damage. Further revealing the disaster mechanism and proposing the engineering treatment measures. The research results indicate that as the deflection angle increases, the vertical relative compression deformation of the segment that is detaching from the shield tail (segment-DFST) becomes more significant. The plastic strain of the internal bolts inside the two segments in direct contact with the shield shell is mainly related to the radial and longitudinal dislocation. The increase in the deflection angle will lead to a more significant increase in the adjacent dislocation on both sides and the internal dislocation. The plastic strain of the internal bolts of the segment that is completely in the shield shell (segment-CSS) is more influenced by joint opening and longitudinal dislocation under the lower eccentric compression (LEC) state. The plastic strain of the internal bolts in segment-DFST is more influenced by radial dislocation and joint opening under the LEC state. The tension damage of the segments mainly occurs on both sides of the circumferential joint and the lower part of the segment-CSS. The compression damage of the segments is mainly distributed at the top and bottom of the segment-CSS. The eccentric distribution of jack thrust has the most significant impact on the block damage of the lower part of the segment-CSS. With the increase of the deflection angle, the compression damage and distribution range of the blocks at the bottom of the segment-DFST increase sharply. The compression damage and distribution range of the segment-CSS gradually spread from the upper and lower parts to the middle of the segment. The increase in deflection angle will promote the influence of the thrust in LEC state on the compression damage of the lower block of the segment-CSS, and on the tension damage of the upper block of the segment- DFST.

Comprehensive Analysis of the Gradient Porous Transport Layer for the Proton-Exchange Membrane Electrolyzer.

A reasonable porous transport layer (PTL) is crucial to decreasing the mass-transfer loss in proton-exchange membrane water electrolyzers (PEMWEs). In this study, it was experimentally demonstrated that the gradient porosity PTL is beneficial in improving the performance of electrolyzers. The research comprehensively investigates the impact of gradient porosity PTL structures on the performance of the PEMWE, considering mass transfer and interfacial contact. It offers insights into the two-phase (oxygen-water) flow transport mechanisms within the PTLs using a 2D numerical model based on the actual PTL geometry. At the microscopic level, it analyzes how the interfacial contact impacts proton and electron transport mechanisms, affecting not only the contact resistance but also the number of effective catalytic sites for the oxygen evolution reaction. Experimental results demonstrate that the cis-gradient porosity PTL leads to a performance enhancement of 9.3% at 2.2 A/cm2. Numerical simulations reveal that the drivers of oxygen transport include the surface tension of the fibers and the pressure drop influenced by the local PTL porosity. Further analysis indicates that the lower oxygen saturation in the bottom region of the PTL with cis-gradient porosity favors a lower oxygen coverage area in the catalyst layers (CL) since the narrower pore space and higher capillary pressure increase the number of water flow paths into the CL. Overall, this study provides valuable insights for designing high-performance PTLs for use in electrolyzers.

Impact of elevated IOP on lamina cribrosa oxygenation; A combined experimental-computational study on monkeys.

Our goal is to evaluate how lamina cribrosa (LC) oxygenation is affected by the tissue distortions resulting from elevated IOP. Experimental study on monkeys. Four healthy monkey eyes with OCT scans with IOP of 10 to 50 mmHg, and then with histological sections of LC. Since in-vivo LC oxygenation measurement is not yet possible, we used 3D eye-specific numerical models of the LC vasculature which we subjected to experimentally-derived tissue deformations. We reconstructed 3D models of the LC vessel networks of 4 healthy monkey eyes from histological sections. We also obtained in-vivo IOP-induced tissue deformations from a healthy monkey using OCT images and digital volume correlation analysis techniques. The extent that LC vessels distort under a given OCT-derived tissue strain remains unknown. We biomechanics-based mapping techniques: cross-sectional and isotropic. The hemodynamics and oxygenations of the four vessel networks were simulated for deformations at several IOPs up to 60mmHg. The results were used to determine the effects of IOP on LC oxygen supply, assorting the extent of tissue mild and severe hypoxia. IOP-induced deformation, vasculature structure, blood supply, and oxygen supply for LC region. IOP-induced deformations reduced LC oxygenation significantly. More than 20% of LC tissue suffered from mild hypoxia when IOP reached 30 mmHg. Extreme IOP(>50mmHg) led to large severe hypoxia regions (>30%) in the isotropic mapping cases. Our models predicted that moderately elevated IOP can lead to mild hypoxia in a substantial part of the LC, which, if sustained chronically, may contribute to neural tissue damage. For extreme IOP elevations, severe hypoxia was predicted, which would potentially cause more immediate damage. Our findings suggest that despite the remarkable LC vascular robustness, IOP-induced distortions can potentially contribute to glaucomatous neuropathy.

Performance Properties and Finite Element Modelling of Forest-Based Bionanomaterials/Activated Carbon Composite Film for Sustainable Future

Thanks to its highly crystalline structure and excellent thermal, optical, electrical and mechanical properties, carbon and its derivatives are considered the preferred reinforcement material in composites used in many industrial applications, especially in the forest and forest products sector, including oil, gas and aviation. Since hydroxyethyl cellulose (HEC) is a biopolymer, it has poor mechanical and thermal properties. These properties need to be strengthened with various additives. This study aims to improve the thermal and mechanical properties of hydroxyethyl cellulose by preparing hydroxyethyl cellulose/activated carbon (HEC/AC) composite materials. With this study, composites were obtained for the first time and their mechanical properties were examined using a 3D numerical modeling technique. The thermal stability of the prepared composite materials was investigated via thermal gravimetric analysis (TGA). The samples were heated from 30 °C to 750 °C with a heating rate of 10 °C/min under a nitrogen atmosphere and their masses were measured subsequently. The mechanical properties of the composites were investigated via the tensile test. The viscoelastic properties of the composite films were determined with dynamic mechanical thermal analyses (DMTA) and their morphologies were examined with scanning electron microscopy (SEM) images. According to the results, the best F3 sample (films containing 3 wt.% activated carbon) had an elastic modulus of 168.3 MPa, a thermal conductivity value of 0.068 W/mK, the maximum mass loss was at 328.20 °C and the initial storage modulus at 30 °C was 206.13 MPa. It was determined that the hydroxyethyl cellulose composite films containing 3 wt.% activated carbon revealed the optimum results in terms of both thermal conductivity and viscoelastic response and showed that the obtained composite films could be used in industrial applications where thermal conductivity was required.

Turbidity assessment in coastal regions combining machine learning, numerical modeling, and remote sensing

ABSTRACT Machine learning models for water quality prediction often face challenges due to insufficient data and uneven spatial-temporal distributions. To address these issues, we introduce a framework combining machine learning, numerical modeling, and remote sensing imagery to predict coastal water turbidity, a key water quality proxy. This approach was tested in the Great Lakes region, specifically Cleveland Harbor, Lake Erie. We trained models using observed and synthetic data from 3D numerical models and tested them against in situ and remote sensing data from PlanetLabs' Dove satellites. High-resolution (HR) data improved prediction accuracy, with RMSE values of 0.154 and 0.146 log10(FNU) and R2 values of 0.92 and 0.93 for validation and test datasets, respectively. Our study highlights the importance of unified turbidity measures for data comparability. The machine learning model demonstrated skill in predicting turbidity through transfer learning, indicating applicability in diverse, data-scarce regions. This approach can enhance decision support systems for coastal environments by providing accurate, timely predictions of water quality variables. Our methodology offers robust strategies for turbidity and water quality monitoring and holds significant potential for improving input data quality for numerical models and developing predictive models from remote sensing data.

Strong bottom currents in large, deep Lake Geneva generated by higher vertical-mode Poincaré waves

Although internal seiches are ubiquitous in large, deep lakes, little is known about the effect of higher vertical-mode seiches on deepwater dynamics. Here, by combining entire summer season current and temperature observations and 3D numerical modeling, we demonstrate that previously undetected vertical mode-two and mode-three Poincaré waves in 309-meter deep Lake Geneva (Switzerland/France) generate bottom-boundary layer currents up to 4 cm s−1. Poincaré wave amphidromic patterns revealed three strong cells excited simultaneously. Weak hypolimnetic stratification (N2 ≈ 10−6s−2), typical of deep lakes, significantly modified the wave structure by shifting the lower vertical node in the lake’s center from ~75-meter depth (without stratification) to ~150-meter depth (with stratification). This shift induces shear in the middle of the hypolimnion and strengthens bottom currents, with important implications for hypolimnetic mixing and sediment-water exchange. Our findings demonstrate that classical concepts based on constant temperature layers cannot correctly characterize higher vertical-mode Poincaré seiches in deep lakes.

A Proof-of-Concept Study of Stability Monitoring of Implant Structure by Deep Learning of Local Vibrational Characteristics

This study develops a structural stability monitoring method for an implant structure (i.e., a single-tooth dental implant) through deep learning of local vibrational modes. Firstly, the local vibrations of the implant structure are identified from the conductance spectrum, achieved by driving the structure using a piezoelectric transducer within a pre-defined high-frequency band. Secondly, deep learning models based on a convolutional neural network (CNN) are designed to process the obtained conductance data of local vibrational modes. Thirdly, the CNN models are trained to autonomously extract optimal vibration features for structural stability assessment of the implant structure. We employ a validated predictive 3D numerical modeling approach to demonstrate the feasibility of the proposed approach. The proposed method achieved promising results for predicting material loss surrounding the implant, with the best CNN model demonstrating training and testing errors of 3.7% and 4.0%, respectively. The implementation of deep learning allows optimal feature extraction in a lower frequency band, facilitating the use of low-cost active sensing devices. This research introduces a novel approach for assessing the implant’s stability, offering promise for developing future radiation-free stability assessment tools.

Breaching of sand dikes: assessment of 1D and 2D numerical models against laboratory experiments

Dike failures often induce highly damaging floods. Improved understanding of the inherent mechanisms is important to predict and prevent dike failures. This research focuses on sand dike failure by overtopping. During the experiments, the evolution of nine sections was monitored using laser-sheet while the water level in the upstream reservoir was captured using ultrasonic gauges. The impact of the grain size was studied by comparing a fine and a coarser sand. Even though the failure mechanisms look similar in both cases, some differences could be observed in the evolution of the geometry of the dike. Finally, the failure was simulated with 1D and 2D models. The 1D model shows good results for the initial stage of the dike evolution and in predicting the evolution of the width of the breach. The 2D model predicts the morphological evolution of the dike more accurately but slightly overestimates the widening of the breach.

Prediction of fatigue life of a bolted joint in railway steel arch bridge using multiaxial fatigue criteria

Fatigue represents a critical condition for infrastructure subjected to repeated cyclic loads, such as steel railway bridges. The literature offers several methods to estimate fatigue life, consisting of three main phases: cycle counting, fatigue damage criterion, and damage accumulation criterion. Applying S-N curves might not be conservative in the case of railway bridges subjected to traffic because the stress-time history is complex and cannot be reduced to a sinusoidal history. Additionally, the presence of a multiaxial stress state must be considered. Therefore, this work compares eight multiaxial fatigue damage criteria for evaluating fatigue life in a scenario between high and low-cycle fatigue. Specifically, the authors considered four low-cycle fatigue criteria, namely Smith–Watson–Topper (SWT), Kandil, Brown and Miller (KBM), Glinka, Fatemi and Socie (FS), and four high-cycle fatigue criteria, Crossland, Basquin and the methods recommended by Eurocode 3 and British Standard. The rainflow counting method in ASTM E1049-85 (2011) and Miner’s rule for damage accumulation were used. The Polcevera railway steel bridge was selected as a case study. A 3D numerical model was developed for this purpose using Midas Civil software, taking into account the material non-linearity of the bridge’s elements. Once the area with the highest stress concentration was identified, a detailed analysis was conducted to estimate the stress and strain time histories induced by train traffic. A sensitivity analysis was conducted after critically comparing the eight methods for predicting fatigue life to assess the impact of traffic parameters, train velocity, axle load, and convoy length on fatigue life. It has been found that the criteria considering axial stress tend to overestimate the number of fatigue cycles to failure compared to the criteria, including the effect of shear stress components.

Assessment of Load Test Results on a Sheet Pile Quay Wall: The Potential of 3D Numerical Modeling

Assessment of Load Test Results on a Sheet Pile Quay Wall: The Potential of 3D Numerical Modeling

Numerical modelling and measurement of the E-I characteristics of MgB2 wire in sub-cooled water ice

This work presents a comprehensive 3D numerical model of MgB2 multi-filamentary superconducting wires using the Finite Element Method (FEM) software, COMSOL Multiphysics® 6.0. The study aims to investigate the electro-thermal behavior of MgB2 composite wires during standard transport measurements at various initial temperatures under subcooled water ice conditions. By solving a series of partial differential equations governing heat transfer and dynamic current transport, the model provides detailed insights into the wire’s performance. The simulation results are rigorously compared with experimental E-I characteristics measured for 6-filament MgB2 wires with internal copper stabilization. This comparison validates the model and highlights its capability to predict the behavior of superconducting wires under cryogenic conditions. The findings offer valuable data on the current distribution, ohmic losses, and overall thermal stability of the composite wires, contributing to the advancement of cryogen-free superconducting technologies. This study bridges the gap in the literature regarding the electrothermal dynamics of MgB2 wires cooled by subcooled water ice, providing a foundation for further research and practical applications in high-field generation devices.

Improving Wastewater Heat Recovery Using Phase Change Material Heat Exchangers: A Numerical Study of Thermal Performance

ABSTRACTIndustrial processes often generate substantial amounts of wastewater with significant thermal energy content, which is typically discarded as waste. A promising approach to increase energy efficiency and advance sustainable resource management is waste water heat recovery. Utilizing a phase change material (PCM) to extract waste heat from wastewater and transfer it to cold water is an innovative method that separates the demand and supply of heat, while also integrating storage and transmission within a single heat exchanger (HE). A 3D numerical model of PCM‐based HE is developed and simulated. The thermal behavior of PCM and preheating of cold water are investigated in this study. In order to increase the thermal conductivity of the PCM, fins are strategically positioned. Around 71.13% of melting time is reduced by adding fins. Further, the 10° orientation of the fins is also numerically observed and it is found that it helps to improve natural circulation of molten PCM. Thus, melting time is reduced by 34% compared to the vertical fin. A 3.5°C–4.5°C temperature rise in cold water is obtained with the inclined fin, which is 14.28% higher than the vertical fin model.

Ocean Circulation on Tide-locked Lava Worlds. I. An Idealized 2D Numerical Model

A magma ocean is expected to exist on the dayside of tide-locked planets if surface temperature exceeds the melting temperature of typical crust. As highly prioritized targets for the James Webb Space Telescope, more information about the surface and atmosphere of lava planets will soon be available. In most previous studies of lava planets, the system is typically assumed to be vigorously convecting and isentropic. This implies a magma ocean depth reaching O (104–105) m, determined by the adiabats and melting curves. In this study, we aim to simulate ocean circulation and ocean depth on tidally locked lava worlds using an idealized 2D (x–z) model developed by the authors. Our simulation results show that under zero or a small internal source, the maximum zonal current speed ranges from 0.1 to 1.0 m s−1 and the magma ocean depth remains O (100) m, being more than 100 times shallower than that predicted in a fully convecting system. We demonstrate that the ocean heat transport divergence is consistently smaller than the stellar insolation by 1–2 orders of magnitude. Consequently, the impact of ocean circulation on the thermal phase curve of tidally locked lava worlds is minimal in observations.