Multi-physics Field Coupling Model Research Articles

Egg-tray-inspired concave foam structure on pore-scale space radiation regulation for enhancing photo-thermal-chemical synergistic conversion

Solar-to-fuel is an approach of converting concentrated solar high-temperature heat radiation to high-value chemical fuel, providing sustainable means for large-scale solar energy storage. However, the inefficient space radiation regulation and unclear photo-thermal-chemical multiphysics synergy limit solar to fuel conversion. To effectively improve photo-thermal-chemical conversion, here, we propose a novel idea of using an egg-tray-inspired concave structure in foam solar receiver-reactors for pore-scale space radiation regulation. The multiphysics field coupling model is accurately constructed to truly describe the complex radiation energy conversion process. Experimental and numerical results illustrate that, the proposed egg-tray-inspired concave structure can achieve the better radiation absorption and transmission, multi-field synergy and thermochemical conversion. The solar radiation absorption capacity can be increased by 7.05 %. The improvements reach a maximum efficiency of 3.17 % for photo-thermal conversion and 9.77 % for photo-chemical conversion. The excellent synergistic conversion of solar-to-fuel opens a new pathway towards accelerating energy transition and upgrading.

Motion Error Mechanism Analysis and Simulation Verification of Ocean Electric Field Sensor

The electric field measurement based on Unmanned Underwater Vehicle (UUV) can monitor and evaluate real-time electric field of underwater targets in motion, which has the ability to adapt to harsh marine environments. However, electric field sensors generate new errors during underwater motion, and there is still absence of studies on the error theory and simulation. To address this, the error generation mechanism of Ag/AgCl electrodes induced by the flow field was analyzed in this paper. A coupled mathematical model of flow-chemical-electric multi-physical field was established for the first time, and finite element simulation analysis was carried out. The results show that the change value of electrode surface potential under the influence of flow rate is basically in agreement with the empirical formulae. R-squared value of the two fits reaches up to 0.968, and RMSE value is less than 0.003, confirming the robustness of the model and simulations. The multi-physical field coupling model and simulation method proposed in this paper can provide theoretical and methodological support for the design of electric field sensors and motion error correction.

Acoustic properties of underwater acoustic metamaterials based on multi-physical field coupling model

In this paper, according to the internal structure of underwater acoustic metamaterial, a multi-physical field coupling model of underwater acoustic metamaterial is established by using finite element analysis. Based on the model, the influence of typical underwater acoustic metamaterial structure and material parameters on sound absorption performance is studied. The results show that increasing the height or radius of the local resonance mass unit in the metamaterial is beneficial to improve the low frequency sound absorption performance. With the increase of the distance between mass elements and the thickness of elastic material, the acoustic absorption performance increases first and then decreases. Increasing the elastic modulus of elastic material of the local resonance unit or matrix will lead to the decrease of low frequency sound absorption performance of the material and the improvement of high frequency sound absorption performance. Increasing the loss factor of elastic material of the local resonance unit or matrix material can broaden the sound absorption band. These rules can provide guidance for the design of underwater acoustic metamaterials.

Multi-objective optimization design and sensitivity analysis of proton exchange membrane electrolytic cell

Proton exchange membrane electrolytic cells (PEMECs) are considered cleaner energy-conversion devices with potential commercial applications in hydrogen production. However, the heat- and mass-transfer characteristics inside the cell remain unclear, and its performance should be optimized to achieve future commercial applications. A three-dimensional multi-physical field-coupling model is developed for the PEMEC. Subsequently, a multi-objective optimization design is used to optimize the structural and operational parameters of the cell based on a neural-network regression model. The results of the sensitivity and response-surface analyses indicate that the initial working temperature has the most significant impact on the reaction temperature, the current density is increased by up to 65.22% under the coupling effects of temperature and flow rate. The cell performance is also enhanced by the increased channel width and depth, although this is accompanied by limitations. Under the combined effects of increasing the working temperature and channel width or height, the current density can be increased by a maximum of 65.22% and 38.61%, respectively. The improvement in cell performance requires a trade-off between improved mass and heat transfer and larger pressure drop, and the optimal design achieves this trade-off. In optimal design, the current density is improved by up to 16.56%, the oxygen mass fraction of the catalytic layer is reduced by 40.90% compared with the original design, accompanied by a reasonable pressure drop and uniform temperature distribution. This study provides a novel perspective for the optimization of the PEMEC to promote its commercial application, offering a reference for further advanced optimization of cell performance and reducing trial-and-error costs. It is also expected to have practical applications in energy conservation and sustainable development.

Evaporation Properties of Water through Floating Porous Structures for Desalination

The floating porous structure consists of an optical absorption layer, a porous layer, and an insulating layer. Water is pumped through a porous structure to the top absorption surface for evaporation. A numerical model of interfacial evaporation of floating porous structure is established. A multiphysical field coupling model for heat transfer, flow, and mass transfer within porous structures is simulated. The transient temperature response, evaporation flux, and vapor concentration distribution inside the structure are calculated. Effects of porous structure characteristics, such as size and porosity, on evaporation performance are discussed. With the increase of structure radius, the evaporation amount increases gradually, but the evaporation per unit area decreases with the radius. With the increase of the structure height, the evaporation amount and the evaporation flux decrease, but the decrease is relatively small. The porosity of the porous layer ε1 has a significant effect on the evaporation performance. The increase of ε1 is beneficial to the evaporation of water. When ε1 < 0.3, the effect of the porosity of insulation layer ε2 on the evaporation performance can be neglected.

Multi-physics Coupled Simulation and Model App Development for Lithium Slurry Batteries

Lithium slurry batteries, as an electrochemical energy storage technology, have the advantages of high operating voltage, large energy density and flexible configuration, and have broad application prospects. Due to the high cost of experiment time, materials traditional experimental methods have low R&D efficiency and the internal reactions and physical fields of batteries are very complex, research on battery performance is difficult and the threshold is high. To overcome this challenge, A new dynamic three-dimensional multi physical field coupling model for lithium slurry flow batteries has been proposed. This model can study the fluid dynamics of slurry batteries, the electrochemistry of lithium electrode reactions, the transport of lithium in solid particles, and the mass balance in storage tanks. Based on this model, we develop model applications using Comsol’s built-in interface. This app has a simple interface and simple operation to reduce the threshold for researchers and improve their research efficiency.

Analysis and Optimization of Contact Material Ablation under the Cumulative Effect of the Number of Breakings of OLTC.

Vacuum on-load tap-changers (OLTC) for converter transformers have a much higher number of breakings than conventional circuit breakers. Contact ablation after several breakings will affect the stability and life of the device. This paper establishes the electromagnetic thermal multi-physical field coupling model of the vacuum interrupter for OLTC based on the finite element analysis method. The thermal field distribution of normal and ablative contact materials during the breaking process was analyzed. The key parameters affecting the contact temperature under the cumulative number of breakings are analyzed and the optimized design is completed. The simulation results show that the contact surface reaches a maximum temperature of 1390 K at 8 ms. There is a significant increase in the area of the high-temperature area on the contact surface. The possibility of re-ignition of the interrupter is increased. Based on the judgment matrix method, the key influencing parameters of the contact temperature rise are analyzed. The final parameters are selected as follows: contact material-CuCr8 alloy, contact seat thickness-2 mm, contact thickness-10 mm, and contact diameter-40 mm.

Coupling flow and electric fields to simulate migration and remediation of uranium in groundwater remediated by electroosmosis and a permeable reactive bio-barrier

Combined remediation technologies are increasingly being considered to uranium contaminated groundwater, such as the joint utilize of permeable reactive bio-barrier (Bio-PRB) and electrokinetic remediation (EKR). While the assessment of uranium plume evolution in the combined remediation system (CRS) have often been impeded by insufficient understanding of multi-physical field superposition. Therefore, advanced knowledge in multi-physical field coupling in groundwater flow will be crucial to the practical application of these techniques. A two-dimensional multi-physical field coupling model was constructed for predicting the uranium degradation in CRS. The study demonstrates that the coupling model is able to predict the uranium plume evolution and rapidly evaluate the performance of CRS components. The results show that field electric direction and flow field strength are the key factors that affect the retardation and remediation performance of CRS. The reverse electric field direction significantly affected the contact reaction time of uranium in the system. The uranium residence time in the reverse electric field was 3.8 d, which was significantly greater than the original electric field (2.0 d). Depending on the voltage, the reverse electric field direction was 16%–36% more efficient than the original direction. The strength of the flow field was about two orders of magnitude higher than that of the electric field, so the groundwater flow rate dominated remediation efficiency. Reducing the flow rate by 1/2 could improve the performance of the system by approximately 66%. In addition, the coupling model can be utilized to design standard CRS for real site of uranium contaminated groundwater. To meet the optimal performance, the direction of the electric field should be set opposite to the flow field. This work has successfully used a coupling model to predict uranium contaminant-plume evolution in CRS and estimate the performance of each component.

A Broadband, High-Power Resonant Piezoelectric Active-Valve Pump Driven By Sandwich Bending Transducers

A resonant piezoelectric active-valve pump driven by the serial connected there-chambers is proposed based on three sandwich bending transducers (SBTs). The pump possesses the superiorities of high bandwidth and high output power. The configuration and driving principle of the pump are designed and studied. The wet modal and frequency response analyses are performed to determine the resonant frequency and output displacement, and their consistencies are also evaluated. The multi-physical field coupling model of the pump is established by bi-directional fluid structure interaction. The influences of frequency and outlet pressure of the pump on flowrate characteristics at different voltages are revealed. A physical prototype of the pump is manufactured and the tested setup is constructed to measure the output performances. This work shows that the maximum flowrate of the pump is 345 mL/min at 1.95 kHz; the maximum pressure can reach up to 242 kPa at 2.05 kHz. Besides, the self-filling pressure is 78 kPa; and the maximum driving power is 432 mW with an outlet pressure of 125 kPa. The results show that the developed pump is expected to be used in the hydraulic drive system of UAV variable swept wing.

Investigation of the Degradation Mechanism of SiC MOSFET Subjected to Multiple Stresses.

The performance requirements for power devices in airborne equipment are increasingly demanding, while environmental and working stresses are becoming more diverse. The degradation mechanisms of devices subjected to multiple stresses become more complex. Most proposed degradation mechanisms and models in current research only consider a single stress, making it difficult to describe the correlation between multiple stresses and the correlation of failures. Then, a multi-physical field coupling model based on COMSOL is proposed. The influence relationship between temperature, moisture, electrical load, and vibration during device operation is considered, and a three-dimensional finite element model is built to investigate the multi-stress degradation mechanism under multi-physical field coupling. The simulation results show that, compared with single-stress models, the proposed multi-stress coupled model can more accurately simulate the degradation process of SiC MOSFET. This provides references for improving the reliability design of power device packaging.

Intermittent injection of carbon dioxide to control the risk of coal spontaneous combustion and methane explosion: A case study in U-type ventilation

The compound risk of coal spontaneous combustion (CSC) and methane (CH4) explosion poses a serious threat to mining safety. Green resource utilization of carbon dioxide (CO2) can help achieve carbon neutrality. Therefore, CO2 is seen as a means to prevent compound risk of CSC and CH4 explosion. To address the situation at the 4209 working face, a multi-physical field coupling model was established to simulate the CSC and CH4 explosion in the gob of a U-type ventilation system. The accuracy of the model was verified against measured data from the gob. Following the injection of CO2 into the gob, the volume of the compound risk area was significantly reduced. The effects of intermittent CO2 injection were compared to those of continuous injection, and it was determined that intermittent injection was the preferred method, taking injection cost into account. Three injection frequencies were tested, with F= 1/2 d showing the optimal effect. When the injection frequency was set to F= 1/2 d, and three CO2 injection flow rates were tested, it was demonstrated that a flow rate of 141.3 m3/h provided the most effective risk reduction while meeting the required CO2 concentration in the working face.

Numerical Simulation Analysis of Three-phase Submerged Arc Furnace Using the Multi-field Method

To reveal the distribution law of the multi-physics field in the smelting of the submerged arc furnace, the temperature distribution in the furnace for a given electrode diameter was studied, and the multi-physics field coupling model of the submerged arc furnace was established, based on Maxwell’s equation, Ohm’s law, numerical analysis of fluid governing equations and heat transfer mechanism. The results show that the current density is mainly affected by the skin effect on the surface of the electrode, with a maximum value of 35000 A/m2; the Joule heat is mainly concentrated at the bottom of the electrode in the material layer; the maximum value of the magnetic flux density is at the electrode pole center circle, about 0.02 T; the flow of the fluid in the molten pool is affected by the Lorentz force and gravity, and the distribution of the Lorentz force in the slag layer is more obvious; the maximum temperature in the furnace reaches 2500°C and is located at the bottom of the electrode, which is gradually transferred from the material layer to the slag layer.

Magnetic-directed fillers migration during micro-injection molding of magnetic polypropylene nanocomposite surfaces with uplifted light trapping microarchitectures for freezing delay and photothermal-enhanced de-icing

Micro-roughness and low-surface-energy anti-icing surfaces attract tremendous interest from researchers due to superhydrophobicity and low ice affinity. However, the rapid fabrication of superhydrophobic surfaces (SHS) without developed microstructure via template methods has been the bottleneck for further applications. In this work, ferroferric oxide (Fe3O4) loaded with graphene (GP) as magnetic nanoparticles are introduced into the polypropylene (PP) matrix as a heat vehicle for superhydrophobic anti-icing/de-icing surfaces. Microarchitectured PP/GP/Fe3O4 surfaces are fabricated via a combining method of micro-injection molding and magnetic attraction. An analysis of directed particles migration with magnetic attraction is conducted using a multi-physical field coupling model. The magnetic attraction boosts micropillars with a height from ∼85 to ∼150 μm and keeps surfaces maintaining water contact angles at a high level (∼153°) and the stable air plastron for repetitive droplet impacting at an initial velocity of 1 m s−1. With full-grown micropillars, light can be absorbed more efficiently by elongating the optical path for multiple reflections to occur. In comparison with neat PP surface, the light-to-heat performance of the composite surface shows an increase in temperature from ambient to 94 °C within 67 s under one sun irradiation at an intensity of 1 kW m−2 and a decrease in ice adhesion strength from ∼30 to ∼9 kPa within the same period. The photothermal efficacy of the magnetic particles confers a prolonged delay in icing on SHS. A practical application of manufacturing of SHS is expected to be possible due to their excellent passive anti-icing and active de-icing properties for outdoor injection parts.

Simulation Study on Microstructure of Magnetic Field Assisted ECAM

Electrochemical additive manufacturing (ECAM) technology is a non-thermal metal additive manufacturing technology that is widely used in microfabrication. The quality of additively manufactured moulded parts can be improved by applying magnetic fields with unknown effects of process parameters on additively manufactured microstructures. Therefore, a multi-physical field coupling model for magnetic field-assisted ECAM was developed. The results show that increasing the applied voltage and magnetic field strength can increase the cathode current density and improve the deposition rate and deposition height, but after the applied voltage increases to 4 V, the ion concentration decreases too fast and the concentration polarization occurs, which affects the deposition rate instead. The ion flux reached the maximum at the magnetic field strength of 0.2T. However, the cathode current density is affected by the electrode gap, and the deposition rate decreases with the increase of the electrode gap, and the deposition rate stabilizes after the electrode gap increases to 50 μm. The increase in current density with increasing electrode size may be related to the applied magnetic field.

Improving reservoir permeability by electric pulse controllable shock wave

Controllable shock wave (CWS) parameters such as amplitude, operating area and number of operations are easy to control and have received extensive attention as a potential new technology for reservoir permeability enhancement. Based on the continuous-discontinuous element method (CDEM) and considering the coupling mechanism of reservoir deformation, failure, pore seepage and fracture flow, a multiphysical field coupling model of reservoir permeability enhancement under CWS is proposed. Under the fluid–solid coupling condition, the formation and development dynamic process of reservoir fractures are obtained, and the change of reservoir permeability is also obtained. The compression fracture zone, tensile fracture zone and undamaged zone are formed around the wellbore. After repeated impact, the number of fractures is more sensitive to tectonic stress, the fracture aperture is more sensitive to reservoir strength. Different from hydraulic fracturing, a large number of fractures in different directions will appear around the main fracture after repeated impact, forming a complex fracture network similar to spider web, which may be beneficial to improve reservoir permeability. The permeability of reservoirs with different tectonic stresses and strengths increases nonlinearly and monotonicly with repeated impacts. Based on CDEM, the change of reservoir permeability with tectonic stress, strength and impact times is obtained, which is a nonlinear monotonic three-dimensional relationship. Based on that relationship, the parameters of CWS can be controlled to predict the change of reservoir permeability, such as peak pressure, duration, impact times, etc. Therefore, it can optimize the reservoir fracturing scheme and improve the reservoir fracturing efficiency, which has considerable practical significance in engineering.

Coal permeability behaviors and non-uniform deformations under various boundary conditions: Part 2 – modelling study

This article is the second part of the series: modelling study. Physical properties of the coal fractures are not equal to those of coal bulk, which lead to non-uniform deformation between coal bulk and fractures in response to gas adsorption and pressure change. In this study, we defined three kinds of non-uniform deformation indexes: adsorptive non-uniform deformation index (ANDI), mechanistic non-uniform deformation index (MNDI), and comprehensive non-uniform deformation index (CNDI) to quantify the degrees of the non-uniform deformations between coal bulk and fractures, and we established a new multi-physical field coupling model based on these non-uniform deformation indexes. The theoretical solutions of the new permeability model agree well with the experimental solutions. The non-uniform deformation is contributed by the gas adsorption and mechanical action, and closely related to the type of boundary conditions. The ratio of the coal bulk modulus to the fracture modulus and the Langmuir pressure constant of matrix controls the MNDI and ANDI, respectively. In addition, in order to explain the fact that part of the theoretical solution of permeability is inconsistent with the experimental solution under constant effective stress condition, we proposed the concept of modified effective stress, which is obtained by adding an additional effective stress based on the traditional effective stress. The additional effective stress reflects the contribution of other factors to effective stress except confining pressure and pore pressure, such as gas adsorption, temperature change, biological decomposition etc. The modified effective stress is the only variable in the new permeability model. The definitions of the additional effective stress and modified effective stress solve the problem that the theoretical solution of permeability is inconsistent with the experimental solution.

Melting Distribution of Armature in Electromagnetic Rail Launcher

This article established a 3-D transient melting calculation model of the electromagnetic rail launcher (EMRL), considering the combined effects of electromagnetic fields, structural fields, heat transfer, and armature motion. To verify the accuracy of the multiphysics field coupling model, an experiment platform of EMRL that is capable of retrieving the launched armature is set up. Compared with the armature surface profiles obtained from the experiment, the simulation model describes the locations of deeper melting accurately but is not precise enough for the shallower melting. Through analyzing the evolution of the melting region, it is found that the deepest crater forms at the point where the armature begins to melt. Analysis of the heat sources shows that contact resistance heat and body heat are two critical factors in the process of armature melting. Despite the high power of the frictional heat, there is no melting in the region where it exists. It is proven that the proposed model can predict the melting performance of the armature.

Numerical study on power battery thermal management system based on heat pipe technology

In the present work, a power battery pack and a novel thermal management system (TMS) based on the tubular heat pipe (THP) technology are designed according to the parameters of a pure electric light truck and battery. The TMS consists of THPs, power batteries, cooling plates, fins, and equivalent thermal conductivity is used to characterize the excellent thermal conductivity of THP. The heat generation rate of the battery at different discharge rates is obtained by establishing a multi-scale electrochemical–thermal coupling model, which accuracy is verified by the experiment. A multi-physics field coupling model is built to the thermal management system designed for the study. The results show that the battery temperature is higher when the battery is far from the THP in the cooling plate, and the maximum temperature reaches 35.6 °C at 1 C. Furthermore, the temperature difference between batteries is proportional to the discharge rate, and the maximum temperature difference reaches 7 °C at 2 C. The change in inlet temperature and wind speed can only restrain the temperature rise, while the temperature difference of the battery module is always 3.2 °C. When a fin spacing of 3 mm is chosen, the best temperature uniformity of the battery module is achieved at this time. The use of the multi-scale multi-physics field coupling analysis method in BTMS with heat pipes can be used as a reference for future numerical simulations of the same type.

Design and Performance Analysis of a Double-Outlet-Rod Magnetorheological Damper for Impact Load

In order to improve the performance of magnetorheological dampers under impact load, a double-rod magnetorheological damper is designed in this paper, and its multi-physical field coupling model is established. The performance of a double-rod magnetorheological damper under impact conditions is characterized from the aspects of viscosity, velocity, peak pressure, impact energy consumption and viscous damping force ratio. The research contents include: a comparison of dynamic characteristics such as the viscosity, velocity and pressure of the magnetorheological damper under impact conditions and low-speed vibration; the influence of temperature on the mechanical performance parameters of the magnetorheological damper, such as peak pressure, impact energy dissipation and viscous damping force ratio, under impact load; and the establishment of a peak sensitivity function to study the influence of three key structural parameters on the magnetic flux density and impact energy dissipation at the damper damping channel. On the basis of the above theoretical research, an impact test of the processed double-rod magnetorheological damper prototype under different excitation currents is carried out. The results show that the viscosity distribution of the damping channel activation region (i.e., the region where the magnetorheological effect occurs after energization) of the magnetorheological damper under impact is disordered, the region of the structural flow in the semi-solid state is small and the influence of the Coulomb damping force is greatly weakened. When the current is 0.5 A, the viscous damping force accounts for 91.2%, and the viscous damping force plays a major role in buffering energy absorption. With an increase in working temperature, the effect of the Coulomb damping force decreases, and the peak pressure and impact energy consumption of the MR damper decrease greatly. With increasing excitation current, this reduction is further increased. The influence of gap height, piston diameter and effective length on magnetic flux density and impact energy dissipation is determined via the peak sensitivity function. When the change in the structural parameters ∆α is 30%, the change in the piston diameter has the greatest influence on the peak sensitivity of the magnetic flux density, and the peak sensitivity index of the magnetic flux density reaches 25%. The change in clearance height has the greatest influence on the impact energy consumption, and the peak sensitivity index of the impact energy consumption reaches 115%. This shows that the magnetic flux density is most affected by the piston diameter, and the impact energy consumption is most affected by the clearance height. The test results show that the test pressure peak-change curve is consistent with the simulation pressure peak-change curve, and the pressure peak error between the two is within 10%.

The electrodynamics of rod-like microparticles based on optically induced dielectrophoresis.

Due to its characteristics of noncontact, non-damage, high flux, and easy-to-achieve flexible manipulation, optically induced dielectrophoresis (ODEP) technology has been employed to manipulate microspherical biological particles, including separation, enrichment, capture, arrangement, and fusion. However, in nature, biomolecules are morphologically diverse, and some of them are rodlike. In order to illustrate the electrodynamics of rodlike particles under the action of ODEP, a transient multi-physical field coupling model of ODEP chip under the hypothesis of electrical double layer thin layer was established in this paper. The arbitrary Lagrangian-Eulerian method is used to track single-rod particle in the strong coupled flow field and electric field simultaneously. The influence of several key factors, including the applied alternating current (AC) electric voltage, the width of optical bright area, and the initial position of particle, on the trajectory of particle center was analyzed in positive dielectrophoresis (DEP) action and negative DEP action, respectively. Especially, the planar motion process of rodlike particles was discussed together. The research results reveal the electrodynamics behavior of rodlike particles based on the action of ODEP, which may provide theoretical support for the further design of rodlike biological cells manipulation chip based on AC ODEP technology in the future.