Multi-physical Field Coupling Research Articles

Multi-physics field coupling simulation and experimental study of new green and low energy consumption lithium molten salt electrolyser

ABSTRACT A new type of lithium molten salt electrolytic cell was studied by using multi-physics coupling numerical simulation method and verified by experiment. The distribution of temperature, potential, current density, fluid force and flow field in electrolytic cell was investigated. The results show that the minimum pole distance of the cell is 6 mm, which effectively reduces the pressure drop on the electrolyte to 0.1 V. The mixture of electrolyte and lithium metal can effectively transfer mass through the electrode gap, while the resulting chlorine gas acts as a power source for the entire electrolytic cell, and electric field analysis shows a significant reduction in energy consumption, validating the energy saving potential of the new structure. Pilot tests have determined an energy consumption of 28 KWH/kg of lithium with a current efficiency of 87.5%, a nearly 50% reduction in energy consumption and a more than 30% improvement in current efficiency compared to conventional systems.

Surface Integrity and Machining Mechanism of Al 7050 Induced by Multi-Physical Field Coupling in High-Speed Machining

Improving the surface quality and controlling the microstructure evolution of difficult-to-cut materials are always challenges in high-speed machining (HSM). In this paper, surface topography, defects and roughness are assessed to characterize the surface features of 7050 aluminum alloy (Al 7050) under HSM conditions characterized by high temperature, strain and strain rate. Based on multi-physical field coupling, the mechanism of microstructure evolution of Al 7050 is investigated in HSM. The results indicate that the surface morphology and roughness of Al7050 during HSM are optimal at fz = 0.025 mm/z, and the formation of surface defects (adherent chips, cavities, microcracks, material compression and tearing) in HSM is mainly affected by thermo-mechanical coupling. Significant differences are observed in the microstructure of different machined subsurfaces by electron backscatter diffraction (EBSD) technology, and high cutting speeds and high feed rates contributed to recrystallization. The crystallographic texture types on machined subsurface are mainly {110}<112> Brass texture, {001}<100> Cube texture, {123}<634> S texture and {124}<112> R texture, and the crystallographic texture type and intensity are significantly affected by multi-physical field coupling. The elastic–plastic deformation and microstructural evolution of Al7050 alloy during the HSM process are mainly influenced by the coupling effects of multiple physical fields (stress–strain field and thermo-mechanical coupling field). This study reveals the internal mechanism of multi-physical field coupling in HSM and provides valuable enlightenment for the control of microstructure evolution of difficult-to-cut materials in HSM.

Dislocation density evolution and related model construction of Ti60 alloy under multi-physical field coupling

Electrically-assisted forming (EAF) is a novel process that has shown the potential to reduce stress, improve formability, and accelerate recrystallization. However, the lack of a suitable physical coupling model due to the imperfect response mechanism of pulse current to dislocation density limits subsequent EAF finite element simulation. In this study, Ti60 alloy is subjected to periodic electro-assisted tensile (EAT) tests. The effects of current densities and pulse periods on dislocation density are expounded, and a physical coupling model based on dislocation density is established. The results are as follows: pulse current can promote the diffraction peak (001) to shift to a lower angle, and enhance the collision between electrons and atoms, elevating the rate of atomic diffusion. The phenomenon of recrystallization and grain growth leads to a decrease of dislocation density. After necking, the velocity of dislocation motion and annihilation is several times higher than that before necking, causing significant changes in flow stress. The modified Johnson-Cook (JC) model, which considers only temperature (T) and current density (J), exhibits a larger EAARE value after necking. Modified dislocation density (MDD) is a physical coupling model based on dislocation density (ρ), supplemented by current density (J) and temperature (T). The response of this model to flow stress is instantaneous, which can not only reflect the remarkable characteristics of the EAT process but also greatly improve the prediction accuracy after necking.

Optimization of the separation chamber structure of a pneumatic dry low-intensity drum magnetic separator based on a multi-physical field coupling model

ABSTRACT Dry magnetic separator is the workhorse for processing fine-grained magnetite in arid and remote regions. In this study, a pneumatic dry low-intensity drum magnetic separator (PDLDMS) with a side vertical upward feeding was designed and optimized based on a multiphysics numerical model. The structural parameters of the separation chamber were designed and optimized by predicting the separation performance and particle dynamic trajectory of the PDLDMS. All predictions indicated that the structural parameters of the separation chamber affected the capture behavior of particles with different sizes and relative magnetic permeability. An appropriate increase in the spacing of the separation chamber was conducive to reducing the entrapment of the particles with a lower relative magnetic permeability and improving the grade of the concentrate. An appropriate increase in the waveform amplitude of the separation chamber was conducive to improving the recovery of the fine-grained particles with a higher relative magnetic permeability and improving the recovery of the concentrate. The optimum PDLDMS performance was achieved at a separation chamber spacing of 40 mm and a separation chamber waveform amplitude of 20 mm. By comparing the experimental results with simulated results, the accuracy of the PDLDMS recovery and grade prediction results were verified.

Multi-Field Coupling Models of Coal and Gas and Their Engineering Applications to CBM in Deep Seams: A Review

In the process of deep coal seam mining, the problem of coal–gas compound disasters is increasingly prominent, with the safe and efficient extraction of gas serving as the key to disaster reduction. A deep coal seam gas extraction project is a complex coupled system involving multiple physical fields, such as stress fields, gas flow fields, and energy. Constructing a systematic theoretical framework of multiphysics field coupling is crucial for improving the safety and efficiency of gas extraction. This paper examines all existing multiphysics field coupling theories. It then suggests a theoretical modeling framework that is based on three important scientific issues: the coal deformation law, the gas flow law, and the coal porosity and permeability spatiotemporal distribution law. We further analyze the application and development of the model in typical coal seam gas extraction engineering on this basis. Finally, this paper points out the shortcomings of the current research and looks forward to the future research directions for the coupled coal and gas multiphysics field model, aiming to provide a theoretical basis and guidance for the model’s construction and application in gas extraction engineering.

Numerical study of thermal safety of passive semiconductor bridges based on multiphysics field coupling

Abstract In order to study the thermal safety of high passivation semiconductor bridges, a NTC (negative temperature coefficient) thermistor is integrated into the SCB (Semiconductor Bridge), and the SCB-NTC shunt and the temperature change in the bridge area and the temperature change in the bridge area of the SCB are investigated based on the COMSOL under the excitation of different constant current sources. The results show that NTC has an obvious inhibiting effect on the temperature increase of SCB bridge area. The thermal equilibrium temperature of the bridge area is about 172 °C under 1.5 A excitation condition; under 2 A excitation condition, the thermal equilibrium temperature of the bridge area is about 206 °C. The current flowing through the NTC under 1.5 A excitation condition rises from 0.45 A to 0.78 A and stays unchanged; under 2 A excitation condition, the current flowing through the NTC rises from 0.6 A to 1.35 A and stays unchanged. By integrating the NTC on the SCB, the NTC thermistor shunt can reach 52%∼67.5%, which can reduce the temperature of the bridge area by 55%∼70%. The above simulation results are compared with the experimental results, and the simulation results are in high agreement with the experimental results.

Simulation of microwave heating reactor for hydrofluoric acid based on multi-physical field coupling

Simulation of microwave heating reactor for hydrofluoric acid based on multi-physical field coupling

Evaluation of the migration and environmental effects of metal elements within cementitious gangue-fly ash backfill in underground coal mines

Cementitious gangue-fly ash backfill (CGB) is used as a green mining technology worldwide. However, under the coupled effects of geological stress and groundwater, the metal elements in the CGB tend to migrate into nearby strata, which can consequently result in pollution of the groundwater environment. In this paper, the influence of initial pH and stress damage on the migration behavior of metal elements in CGB is quantitatively studied through the multi-physical field coupling model of stress-permeability-concentration. The enhanced Nemerow index evaluation method is used to comprehensively evaluate the impact of these metal elements migration behaviors on the groundwater environment. The research results show that: (1) When the stress damage of the CGB increases from 0.76 to 0.95, the Darcy velocity at the bottom of the CGB first increases, then decreases, and finally stabilizes at 2.01×10−7 m/s. The longest time to reach the maximum Darcy velocity is 3 a. (2) When the damage of the CGB is 0.95, the farthest migration distances of Al, Cr, Mn, Fe, Ba, and Pb are 40.5, 34.0, 29.8, 32.9, 38.8 and 32.1 m, respectively. (3) The alkaline environment stimulates the migration of Al, Cr, Fe, Mn, and Pb, whereas Ba migrates farther under acidic conditions. The farthest migration distance of Ba is 31.6 m under pH 3. (4) The enhanced Nemerow index indicates that when stress damage increases from 0.76 to 0.95, the areas with poor water quality increase from 0 to 1.71%, and no area is classified as very poor grade. When the initial pH changes from 3 to 11, 100% of the region is classified as fair or above. The initial pH of the CGB has a relatively slight influence on the groundwater environment. This study provides experimental data and theoretical basis for the environmental evaluation of CGB.

Study on the reliability verification method of electronic transformer under multi-physical field coupling effect

Abstract With the development of smart grid technology, electronic transformers play an important role in substations, but their reliability is affected by a variety of environmental factors, such as temperature, humidity, and electromagnetic interference. Existing test standards fail to comprehensively simulate the operation of electronic transformers in real environments, resulting in their insufficient reliability. In this study, we propose a reliability verification method for electronic transformers that considers the effects of multiple physical fields, which mainly includes an electrical fast transient pulse group interference immunity test with temperature and humidity considerations, a conducted interference immunity test with radio frequency induction, and a surge interference immunity test. The test results show that the immunity of the collector is greatly affected when the electronic transformer is subjected to electromagnetic interference superimposed on temperature and humidity field changes and is prone to failure in extreme cases. This study provides a practical basis for the scenario application of electronic transformers.

The Influence of Magnetic Fields on the Operational State and Velocity of Smart Projectiles

Abstract The electromagnetic railgun, as a novel launching technology, held great potential for development. However, due to the strong magnetic interference during the launch process, most of the electromagnetic railguns that were being researched at that time could only launch kinetic projectiles. By incorporating magnetic shielding materials within the projectile to mitigate the impact of external magnetic fields on the internal circuitry, it became feasible to launch guided missiles and range-determining projectiles. This advancement could have significantly enhanced the versatility of electromagnetic railguns. The paper established a multi-physical field coupling model between the projectile and the magnetic field using the COMSOL software. First, the shielding efficiency of the shielding body inside the projectile as it passed through a uniform magnetic field was calculated. At the same time, when the projectile moved in the magnetic field, it was subjected to an action force exerted by the magnetic field. The paper studied the force relationship between the projectile and the magnetic field and the deceleration of the projectile, and found that the magnetic field had a role of accelerating the projectile first and then decelerating it. The acceleration stage was much smaller than the deceleration stage. The projectile also generated eddy currents in the magnetic field, causing the temperature of the projectile to rise. The experimental results obtained were basically consistent with the numerical calculation results. Under the shielding effect, the internal circuits of the projectile were greatly reduced by the interference of the magnetic field, and the speed and temperature of the projectile remained within a reasonable range. This also provided certain reference for the design of electromagnetic coil gun muzzle velocity measurement devices and proximity fuse signal transmission devices.

Fluid and thermal effect on temperature-dependent power increase of electric vehicle's permanent magnet synchronous motor using compound water cooling method

Taking advantage of compound housing water jacket (HWJ) and hollow-shaft water jacket (SWJ) cooling based on the temperature-dependent power of permanent magnet synchronous motor (PMSM) is a solution for enhanced electric vehicle (EV) performance. The fluid and temperature field of a 40 kW PMSM at three typical continuous working points were studied, covering low to high speeds of EVs. The influence of different coolant flowrates on power of motor was obtained by multi-physics field coupling analysis method. The impact of current control modes was also investigated. 3D computational fluid dynamics (CFD) conjugate heat transfer calculation combined with 3D lumped parameter thermal network (LPTN) was adopted to calculate the flow and temperature. Temperature-dependent material properties were taken into consideration in electromagnetic finite element analysis (FEA). The models were modified and validated by experiments. Once compounding SWJ on the basis of a strong HWJ cooling, the PM temperature can continue to decrease over 20 degC. The insensitive characteristic of PM temperature towards SWJ flow rate was observed. Under constant current control mode, 3.8 %, 6 % and 4 % PMSM power enhancement by compound cooling were proved at three typical working points. Under current open-loop, 7 %, 16 %, and 10 % increases with compound cooling were confirmed.

Numerical simulation of temperature in forming surroundings for E-Glass fiber

In spinning, the temperature of the glass melt and the forming surroundings play a crucial role in determining the diameter of the electrical glass (E-glass) filament. It is essential to control or predict the temperature of the forming surroundings. In this study, a simplified cooling model of the fin for G75 E-glass fiber was constructed and simulated to explore the influence of ambient temperature on the forming process of E-glass fiber. The multi-physical field coupling of solid-fluid conjugate heat transferring and surface-to-surface radiation imitates the cooling model. The temperature of the bottom of the bushing plate was measured with an infrared thermal imaging instrument, and the ambient temperature of the area of filament root forming was measured with a thermocouple. Considering the device is fixed, the key experimental variable of the numerical simulation is the distance from the top of the cooling fin to the bottom surface of the bushing plate. The simulated results are compared with the actual measurements, proving that it is feasible for the simplified cooling model to simulate the forming of E-glass fiber. The results of numerical simulations also show that (1) the temperature of the glass melt at the outlet of the nozzle is 1400 K and the ambient temperature of the filament root forming dropped by >500 K; (2) when the top of the cooling fin is 4 mm away from the bottom surface of the bushing plate, the fin has the best cooling effect on the E-glass fiber.

Simulation and experimental evaluation of a vane-type magnetorheological damper based on multi-physics field coupling

This work aims to accurately evaluate the nonlinear behaviors of the vane-type magnetorheological (MR) damper through multi-physics field coupling analysis. The working principle of the vane-type MR damper is introduced, and the output torsion model is derived. Considering that the performance of the MR damper is affected by the coupling of electromagnetic field, flow field, thermal field, and solid mechanics, the finite element software COMSOL is used to simulate the multi-physics field inside the MR damper. Correspondingly, the mechanical performance testing of the MR damper is carried out on the torsional electro-hydraulic servo fatigue testing machine. The test results show that the MR damper can reach a maximum output torsion of 7130 N·m and achieves a high torsion-volume ratio of 4.19 × 107 N·m−2, which proves that it has good mechanical properties as well as the ability to satisfy high torsional requirements in relatively limited space. Finally, a comparative analysis between the simulation and experimental curves is carried out, and it is concluded that the multi-physics field coupling analysis can accurately simulate the mechanical performance and working state of the vane-type MR damper.

Characterization of Particle Size Effects on Sintering Shrinkage and Porosity in Stainless Steel Metal Injection Molding Using Multi-Physics Simulation.

In this study, three stainless steel materials (17-4PH, 316L, and 304) were experimentally simulated using metal injection molding (MIM) technology to explore the size shrinkage behavior and defect formation mechanism of materials with different particle sizes during sintering. The sintering environment was linearly heated to 1250 °C at a rate of 5 °C/min and kept warm for 90 min. Multi-physics field coupling analysis was performed using ANSYS Workbench software. Two different regions were selected to simulate the total deformation trend of the material during sintering. The simulation results were compared with data from SEM and EDS analyses to elucidate the influence of particle size on shrinkage behavior and defect distribution. The findings indicate that the gaps between particles far away from the gate position became larger, the degree of densification decreased, the porosity was higher, and the number of white dot inclusions increased. Among the three materials, 17-4PH, which had the smallest particle size, had a greater sintering driving force, a better degree of densification, a smaller predicted total deformation, and a higher shrinkage rate, which is consistent with the hardness test data and the actual density data. In addition, the densification advantage of small particle size powder is not only related to surface energy but is also closely linked to the uniformity of its microstructure. The analysis in this study further promotes the performance optimization of stainless steel materials, indicates a scientific basis for future process improvements and high-precision parts manufacturing in MIM technology, and points to the development direction for high-performance materials.

Numerical simulation and experimental investigation on the thermal-fluid-solid multi-physical field coupling characteristics of wet friction pairs considering cavitation effect

The coupling characteristics of thermal-fluid-solid multi-physical fields are crucial in determining the operational performance and service life of wet clutches. However, the underlying mechanism behind the influence of cavitation effect on these coupling characteristics remains unclear. Therefore, we propose a numerical solution method for considering cavitation effect in the coupling characteristics based on the multi-physical field coupling platform MPCCI combined with ABAQUS and FLUENT. The distribution patterns and intercoupling relationships among temperature field, flow field, and stress-strain field are comprehensively analyze. The influence of relative speed, cross-sectional shape of oil grooves, and oil flow on the coupling characteristics is investigated. Experimental validation confirms that the proposed model accurately predicts temperature variation by accounting for cavitation effect. The temperature distribution of steel discs is notably affected by the cavitation effect, leading to an elevation in the maximum temperature and uneven distribution characterized by localized hot spots along the circumferential direction. Accounting for the cavitation effect reduces errors between calculated and experimental values of temperature rise. The convective heat transfer coefficient gradually decreases radially, with a more pronounced decrease in the cavitation region. An increase in relative speed and a decrease in oil flow both lead to greater cavitation volume, resulting in higher temperature of steel discs. Among three different cross-sectional shapes of oil grooves investigated, rectangular grooves exhibit larger areas affected by cavitation compared to triangular grooves. These research findings provide a theoretical basis and technical support for accurate prediction of thermal characteristics within high-power wet clutches.

Research on Optimal Design of Ultra-High-Speed Motors Based on Multi-Physical Field Coupling Under Mechanical Boundary Constraints

This study investigates the impact of rotor structure, material selection, and cooling methods on ultra-high-speed motor performance, revealing performance variation laws under multi-physical field coupling. Considering mechanical boundary constraints, we propose an optimization design method based on a multi-physical field coupling model. Using a MaxPro experimental design, initial samples are obtained and fitted using a Kriging surrogate model. The NSGA-2 algorithm is then applied for optimization, with Relative Maximum Absolute Error (RMAE) and Relative Average Absolute Error (RAAE) employed for accuracy evaluation. The Kriging model is iteratively updated based on evaluation results until the optimal design is achieved. This method enhances motor performance, ensures mechanical boundary conditions, and reduces computational load. Experimental results show significant improvements in efficiency and power density. This study provides theoretical support and technical guidance for ultra-high-speed motor design and offers new ideas for related motor research and development. Future work will explore more efficient and intelligent optimization algorithms to continuously advance ultra-high-speed motor technology.

Multi-physical field coupling effect in micro pin-fin channel cooling with coaxial-like through-silicon via (TSV) for three-dimensional integrated chip (3D-IC)

Through-silicon via (TSV) technology offers significant advantages for three-dimensional integrated chip (3D-IC) by enabling higher integration densities and faster signal transmission rates. The increased power density of 3D-IC poses substantial thermal management challenges. Microchannel cooling is widely used for chip-level thermal management. However, the balance of heat dissipation and signal integrity between layers of 3D-IC with TSV remains elusive. This work presents a study on the electrical-thermal-force-flow-solid multi-physics field coupling effect of micro pin–fin channel cooling systems embedded with coaxial-like TSVs in 3D-IC, aiming to optimize signal integrity and thermal performance. We analyze the structural parameters of coaxial-like TSVs, such as TSV aspect ratio and pitch ratio, focusing on their impact on signal shielding efficiency and thermal conductivity. The results show that a coaxial-like TSV structure with an aspect ratio of 15 and a pitch ratio of 2.5 reduces the maximum temperature and insertion loss by 3.97% and 3.60%, respectively. This structure is then embedded in a micro pin–fin channel to explore the effect of pin–fin arrangement on heat dissipation at different Reynolds numbers. Using multi-objective optimization through response surface methodology (RSM) and the non-dominated sorting genetic algorithm II (NSGA-II), we obtain a series of optimal solutions for TSV-embedded micro pin–fin. When the weights of heat transfer and pressure drop are balanced, the average Nusselt number increases by 6.8% with a 2% rise in pressure drop. These findings provide valuable insights for the design and optimization of high-performance 3D-IC cooling systems.

Low Noise Optimization Design of Integrated Permanent Magnet Synchronous Motor Based on Multi-Physical Field Coupling

Low Noise Optimization Design of Integrated Permanent Magnet Synchronous Motor Based on Multi-Physical Field Coupling

Digital twin water conservancy early warning system based on physical level and numerical simulation in intelligent water conservancy construction

Abstract. In 2023, the Central Committee of the Communist Party of China and The State Council issued the Overall Layout Plan for the Construction of Digital China, emphasizing the construction of a smart water conservancy system with digital twin basins as the core. The Guangxi Zhuang Autonomous Region government has clearly proposed to actively build a "digital twin Pinglu Canal", and attaches great importance to the construction of digital twin platform application services during the construction of the Western land-Sea New Passage (Pinglu) canal. Aiming at the problems such as unsatisfactory early warning effect, inaccurate data and imprecise model of existing smart water conservancy technology, this paper proposes a digital twin system for disaster early warning based on physical level and numerical simulation technology, establishes a visual digital water conservancy model and digital twin smart water conservancy cloud platform, and combines multi-physics field and multi-dimensional coupling algorithm to respond to technical pain points. To achieve scientific and accurate monitoring and intelligent management, and contribute to the construction of digitally empowered Pinglu Canal.

Experimental and simulation study of calcium carbonate non-uniform distribution characteristics of bio-cemented sand

The innovative technology of microbially induced calcium carbonate precipitation (MICP) soil modification is widely used in soil reinforcement, soil remediation, environmental remediation and other fields, and has gradually become a hot research direction. Recent research is more focused on the overall physical and mechanical characteristics of the uniform reinforced specimen. There is limited research on the distribution characteristics of calcium carbonate along the seepage path during the reinforcement process. However, the distribution characteristics of calcium carbonate play a significant role in the physical and mechanical characteristics of the solid, especially in the large-scale MICP reinforcement process. In this study, based on the microbial mineralization reaction tests of different concentrations of cement solution at the laboratory sample scale, the calcium carbonate distribution on the surface of the sample at the microscale SEM observation and the CT scanning reconstruction of the micro pore structure characteristics of the microbial reinforced soil, we discussed the characteristics of the non-uniform reduction of calcium carbonate distribution and porosity in the process of microbial consolidation. Based on the Kozeny-Carman equation, the conceptual model of effective porosity was introduced, and the time relationship between porosity and calcium carbonate precipitation was considered to establish a bio-chemical-seepage multi-physics field coupling model. The precipitation of calcium carbonate in the axial direction of the model sample exhibits an uneven feature of more at the top and less at the bottom, and the distribution characteristics of porosity also show an uneven feature of more at the top and less at the bottom.