Experimental Simulation Methods Research Articles

Analysis of influencing factors on the performance of wavy-shape solar Trombe walls based on orthogonal experimental design and simulation methods

Analysis of influencing factors on the performance of wavy-shape solar Trombe walls based on orthogonal experimental design and simulation methods

Effects of additional transmission chamber on flow dynamics of a pulsed jet in crossflow

This study examines the effects of an additional transmission chamber on a pulsed jet in crossflow using experimental and Large-eddy simulation methods, with a focus on the structural and mixing characteristics of the flow. Three pulse frequencies are selected (f = 20 Hz, 50 Hz, and 100 Hz), and the results of the model with an additional transmission chamber are compared with the round pipe model. The results show that the additional transmission chamber enhances jet penetration, diffusion, and mixing uniformity, particularly at higher pulse frequencies. The additional transmission chamber also alters the exit velocity profile, increasing peak velocity and promoting greater deflection under crossflow. These findings highlight the potential of transmission chambers to optimize pulsed jet performance in applications requiring effective mixing and penetration.

GWASBrewer: An R Package for Simulating Realistic GWAS Summary Statistics.

Many statistical genetics analysis methods make use of GWAS summary statistics. Best statistical practice requires evaluating these methods in realistic simulation experiments. However, simulating summary statistics by first simulating individual genotype and phenotype data is extremely computationally demanding. This high cost may force researchers to conduct overly simplistic simulations that fail to accurately measure method performance. Alternatively, summary statistics can be simulated directly from their theoretical distribution. Although this is a common need among statistical genetics researchers, no software packages exist for comprehensive GWAS summary statistic simulation. We present GWASBrewer, an open source R package for direct simulation of GWAS summary statistics. We show that statistics simulated by GWASBrewer have the same distribution as statistics generated from individual level data, and can be produced at a fraction of the computational expense. Additionally, GWASBrewer can simulate standard error estimates, something that is typically not done when sampling summary statistics directly. GWASBrewer is highly flexible, allowing the user to simulate data for multiple traits connected by causal effects and with complex distributions of effect sizes. We demonstrate example uses of GWASBrewer for evaluating Mendelian randomization, polygenic risk score, and heritability estimation methods.

Impact of liquid crossflow on the discharge coefficient of a gas jet hole on a flat plate

This study combines the experimental and numerical simulation methods to deeply analyze the impact of liquid crossflow on the discharge coefficient of a gas jet hole on a flat plate. Experiments were conducted to examine the influence of momentum flux ratio and theoretical momentum flux ratio on the discharge coefficient under various crossflow Reynolds numbers. It was found that the variation of the discharge coefficient with the theoretical momentum flux ratio clearly reflects the impact of the crossflow boundary layer velocity profile on the discharge coefficient. The rapid growth of velocity in the boundary layer near the wall in the direction normal to the wall surface, or the decrease in the thickness of the boundary layer, both enhance the shearing effect of the crossflow, leading to a decrease in the discharge coefficient. Analysis of the cavity morphology at the hole exit captured by high-speed camera revealed that the averaged profile of the gas–liquid boundary on the symmetrical plane of the jet below the hole can be approximated as a straight line within the scale of the hole diameter, and the sine of the angle between this line and the upper wall surface is roughly equivalent to the normalized discharge coefficient. This relationship was physically interpreted through the analysis of effective and equivalent flow cross-sectional shapes derived from numerical simulation at different crossflow Reynolds numbers and theoretical momentum flux ratios. Additionally, this paper introduces an innovative method for predicting jet flow rate based on image processing technology. A notable feature of this method is that it does not require the measurement of the pressure inside the gas chamber.

Supercritical carbon dioxide chelation extraction of heavy metal ions from drilling fluid waste: Experiment and simulation

This study evaluates the application of supercritical carbon dioxide chelation extraction technology for treating heavy metal ions (Zn2+ and Cr3+) in drilling fluid waste. Through a combination of experimental and molecular dynamics simulation methods, the influence of extraction parameters (temperature, pressure, duration, and chelating agents) on the extraction efficiency are investigated. Findings show that increased duration and pressure significantly improve extraction efficiency, while temperature has a complex effect, initially increasing efficiency but plateauing and slightly decreasing at higher temperatures. The optimum extraction condition with pressure of 220 bar, temperature 348.15 K and an extraction duration of 70 min using ethylene diamine tetraacetic acid (EDTA) as the chelating agent has been determined. Importantly, molecular simulation analysis revealed that citric acid outperforms EDTA in terms of Zn2+ and Cr3+ aggregation by forming larger aggregates with greater numbers of molecules while reducing overall aggregate count. Furthermore, optimization of extraction pressure in the EDTA system shows potential benefits. These results suggest that supercritical carbon dioxide chelation extraction technology has strong potential for environmentally friendly and reliable waste management in the drilling industry. This study represents a significant step forward in developing sustainable solutions for heavy metal removal from drilling fluid waste.

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.

Experimental study on microscopic production characteristics and influencing factors during dynamic imbibition of shale reservoir with online NMR and fractal theory

Dynamic imbibition and displacement between the matrix and fractures in shale reservoirs can significantly enhance oil recovery (EOR) following initial depletion. However, the microscopic production characteristics and seepage mechanisms at different pore scales during the dynamic imbibition process remain incompletely understood. In this study, we established an online physical simulation experiment method that combines dynamic displacement and imbibition based on nuclear magnetic resonance (NMR) and fractal theory, and a series of online NMR water flooding dynamic imbibition experiments were conducted. Through real-time dynamic monitoring of multiphase flow and migration behavior of crude oil in each stage of dynamic imbibition, the microscopic production characteristics and influencing factors were quantitatively studied from the recovery and residual oil saturation field distribution of different scale pores. Additionally, we developed a novel two-dimensional (2-D) NMR interpretation model to investigate the dynamic development characteristics of shale oil injection-imbibition-soaking-production integration, and the multiphase and multi-scale dynamic imbibition crude oil migration models were discussed. The results show that shale oil occurrence pores can be categorized into two types based on the corresponding production mode (imbibition + displacement). The water flooding dynamic imbibition process in shale reservoirs unfolds in three stages: strong displacement and weak imbibition stage characterized by the rapid production of large pores and fractures under displacement action; weak displacement and strong imbibition stage involving the slow production of small pores under reverse imbibition; and dynamic equilibrium stage characterized by weak displacement and weak imbibition. When viewing the entire water flooding dynamic imbibition process as an organism, it becomes imperative to maximize the recovery of large pores while ensuring the recovery degree of small pores. High permeability contributes to better pore throat connectivity and a greater imbibition and displacement production degree. The contribution of the.two production modes to the recovery of small and large pores increased by 4.67 % and 3.17 %, respectively. A negative correlation was observed between high displacement pressure and imbibition recovery, yet it is conducive to the contribution of displacement to total recovery. Notably, fractures can effectively reduce oil-water seepage resistance, and increase the contribution of displacement to recovery by 21.65 %. Finally.a positive correlation was noted between increased imbibition amount and free oil recovery, while residual oil gradually shifted towards adsorbed and organic matter-dominated forms, leading to decreased recoverability. Effectively utilizing the bridge flow conductivity of fractures, fluid imbibition displacement, and carrying effect is crucial for achieving optimal EOR. The findings provide theoretical support for clarifying the interaction between matrix-fracture imbibition and displacement and for the efficient development of shale oil.

Experimental and numerical simulation study on the mass transfer characteristics of static flash evaporation

Due to the short duration and intense nature of static flash evaporation, and limited by the measurement methods, there is still limited understanding of the inhomogeneous characteristics of mass transfer within the waterfilm. This paper studies the spatiotemporal variation of mass transfer characteristics during static flash using experimental and numerical simulation methods. The formation and evolution mechanism of the bubble layer is analyzed, and its impact on the spatial distribution of temperature within the waterfilm is explained. Firstly, it was found that during the flash process, the temperature difference at different heights of the waterfilm first increases and then decreases. Secondly, during the flash process, there is a maximum value of the vapor generation rate within the waterfilm along the height direction of the flash chamber, and there is a spatial inconsistency between the vapor generation rate and the superheat distribution. Thirdly, reducing the initial waterfilm height can improve the consistency between the maximum superheat and the maximum volume fraction, resulting in a higher vapor generation rate per unit mass and an earlier peak appearance. This study contributes to a deeper understanding of flash mass transfer and provides ideas for the future enhancement of flash evaporation.

A combined transport-defect evolution model of microstructure damage in silicon carbide induced by precise irradiation of focused helium ion beams

In this paper, a combined transport-defect evolution multiscale model describing the generation and the evolution of microstructure damage in silicon carbide (SiC) induced by focused helium ion beams is developed. In the proposed model, the transport of helium ions and displaced atoms in the SiC substrate and the generation of point defects are described by the Boltzmann transport equations, while the subsequent defect evolution is characterized by a set of rate equations with the contributions of the modeling of the bubble coalescence as well as the substrate swelling. The validity and superiority of the transport equations are verified by comparing the simulation results with the data from experimental measurements and available simulation methods. The subsurface amorphous profile, onsurface swelling profile, and the spatial and size distribution of helium bubbles in a SiC substrate irradiated by focused helium ion beams are simulated using the proposed multiscale model. The damage morphology simulated by the proposed model is in good agreement with the transmission electron microscopy images at different beam energies and doses. This work provides an effective tool for full-stage modeling of complex evolutionary mechanisms of microstructure damage induced by precise and high-throughput helium irradiation.

Oil/water interface behavior of hesperidin methylchalcone and its application in nano-emulsions

The behavior of hesperidin methylchalcone (HMC) at the oil/water interface was examined through experimental and molecular simulation methods, and a nano-emulsions based on HMC was subsequently fabricated. The findings indicated that HMC spontaneously aggregated at the oil-water interface, leading to a reduction in interfacial tension and an increase in interfacial thickness. Furthermore, its glycoside and benzene ring showed tendencies to interact with water and medium-chain triglyceride, respectively. The HMC addition amount (w), homogenization times (n) and homogenization pressure (p) significantly influenced the formation of the nano-emulsions. The nano-emulsion with an oil-droplet size of 277.26 ± 13.62 nm was obtained at w = 1.0 %, p = 200 bar, and n = 6. When compared to the Tween 20 nano-emulsion, the HMC nano-emulsion demonstrated superior storage stability, antioxidant activity, and lutein bioaccessibility. It could achieve the slow release of HMC. These findings not only broaden the application range of HMC but also contribute to the advancement of functional nano-emulsions.

Adding Yaw System to Improve Wind Energy Utilization of Offshore Wind Turbines

In wind power generation, the wind energy loss caused by yaw and other factors is as high as 50%, which directly leads to the difficulty of greatly improving The efficiency of wind power generating in producing electricity. The development of yaw control system restricts the progress of wind energy utilization, The purpose of this study is to investigate the application and influence of automatic steering of offshore wind turbines in practice. This paper proposes that the automatic yaw system of offshore wind turbine can improve the efficiency of wind power generation. The outcomes of the experiment demonstrate that the wind resources can be fully utilized and the power generation efficiency of the offshore fan can be improved by enabling the offshore fan to automatically turn according to the wind direction. The research has a certain value for the development of new energy power generation technology. In this paper, the method of Simulink simulation experiment is used to demonstrate that the yaw system can improve the wind energy utilization coefficient of offshore fan.

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.

Investigation of the Discharge Coefficient for Laidback Fan-Shaped Holes on Turbine Blades Under Internal Crossflow Condition

Abstract The discharge coefficient of laidback fan-shaped holes on turbine blades under internal crossflow conditions is investigated using experimental and numerical simulation methods. The study is conducted on a linear cascade, with single rows of film holes set on both the pressure and suction surfaces of the test blade, coolant supplied by an internal crossflow channel. The internal crossflow Reynolds number ranged from 39,100 to 78,200, and the pressure ratio ranged from 1 to 1.5. This research considered the effects of internal crossflow Reynolds numbers and hole length-to-diameter ratio on the discharge coefficient of laidback fan-shaped holes. The findings are as follows: internal crossflow increases the inlet loss of film holes and flow separation within the holes, leading to a significant reduction in the discharge coefficient of film holes. Meanwhile, film holes on the pressure surface of the blade exhibit greater sensitivity to crossflow. Under different hole length-to-diameter ratio conditions, the length of the cylindrical section is the primary factor affecting the discharge coefficient, and the magnitude of the discharge coefficient depends on the extent of flow separation within the cylindrical section. The sensitivity of the discharge coefficient to variations in the cylindrical section length decreases once the cylindrical section length exceeds 2.8D for the pressure surface and 2.0D for the suction surface, where the inlet separation region reattaches to the wall. Under plenum conditions, there are significant differences in the discharge coefficients of film holes between the suction surface and pressure surface, especially at pressure ratios below 1.05.

Discussion on the upper limit of HIFU sound pressure measurement based on laser interferometry

Abstract High intensity focused ultrasound (HIFU) technology is a non-invasive treatment technique that can achieve non-invasive treatment of tumors and other diseases. The accuracy of HIFU sound pressure is crucial for the clinical efficacy and safety of HIFU treatment. The sound pressure measurement technology based on laser interferometry is the recommended method for ICE TC87, which has the advantages of high measurement accuracy and good traceability, and is therefore widely adopted as the new generation of sound pressure standards. However, the upper limit of the laser interferometric HIFU sound pressure measurement currently reported is about 10 MPa, which is far lower than the actual sound pressure of HIFU technology. In response to this issue, the upper limit of HIFU sound pressure measurement was discussed from the perspective of laser interference systems. The mathematical relationship between the HIFU sound pressure and the optical and electrical signals of the laser interference system under the condition of nonlinear sound field is established. The mathematical analysis of HIFU sound pressure requirements for the bandwidth of laser interference systems is discussed. Using experimental and numerical simulation methods, the effect of HIFU sound pressure on the bandwidth of a laser interference system under nonlinear acoustic field conditions was studied.

Numerical and experimental investigation of 12 W/60 K high-efficiency coaxial pulse tube cryocooler

Maintaining a low-temperature environment is paramount in pursuing reliable operation for infrared detectors. To address the rising demand for long-wave infrared detectors functioning in low-temperature environments around 60 K, this study investigates the enhanced efficiency of a 60 K coaxial pulse tube cryocooler (PTC) through both simulation analysis and experimental methods. A PTC model was developed using Sage software to optimize parameters such as cold finger size. Analysis of the internal flow field highlighted that variations in cold head temperature, frequency, and input power significantly impact phase angle distribution within the regenerator. Experimental results yielded the same conclusion and confirmed how these critical factors affect the PTC’s performance. Through systematic optimization of simulations and experiments, a cooling performance of 12.7 W/60 K was achieved with an input power of 300 W. Furthermore, when the input power of the PTC was 200 W, a cooling capacity of 9.2 W/60 K was achieved, demonstrating a relative Carnot efficiency of 18.3 %.

Rebar indentation on performance of CFS columns strengthened by rebar at flange-lip

To facilitate easier construction when longitudinally reinforcing cold-formed thin-walled lipped channel steel columns with steel bars, here, both ends of the steel bars used for reinforcement were cut, and the impact on the reinforcement effect was studied through experimental and numerical simulation methods. Seven groups of reinforced column specimens with different indentation lengths and one group of unreinforced specimens were designed, and axial compression tests were conducted. Parametric analyses were performed using the numerical models calibrated by tests. These numerical models included three types of specimens with typical sections and several series of specimens with different steel plate thicknesses. Using these models, the effects of the steel bar indentation length Li, steel bar diameter D, and other factors on the ultimate bearing capacity and deformation of the reinforced specimens were studied. The experimental results indicated that when the steel bar is the same length as the specimen, the compressive bearing capacity of the cold-formed thin-walled lipped channel column can be significantly improved by bonding the steel bar. Additionally, the numerical analysis results indicated that the influence of changing the steel bar diameter D on the bearing capacity of the specimens is not significant when the steel bars are indented within a certain range. As the length of the steel bar indentation increases to a certain extent, the stress concentration at the end of the steel bar becomes more significant, causing local buckling of the specimen and ultimately leading to a sharp decrease in the bearing capacity of the specimen. To achieve reinforcement, facilitate construction, and ensure structural safety, the total indentation length Li of the steel bars should not be >2 cm in practical engineering projects. Considering the economy of reinforcement engineering, it is suggested that steel bars with smaller diameters, i.e., 6 mm, should be selected. Through a comparison between the FEA and the experimental process, it was confirmed that the failure model of the numerical model is basically consistent with the experimental phenomenon, and the bearing capacity deviation was <3.3%. This indicates that the FEM established in this study was reliable.

Experimental and numerical studies on hydrogen leakage and dispersion in underground parking garages: Impact of leakage direction on safety considerations

Hydrogen leakage in confined spaces poses significant safety risks in hydrogen energy applications, potentially leading to fires and explosions. This paper focuses on the accident scene of hydrogen leakage and dispersion in underground parking garages. A medium-scale model (1/10) of an underground parking garage is designed and built to study the characteristics of the dispersion of hydrogen leaked from hydrogen fuel cell vehicles (HFCVs) in underground garages using experimental and numerical simulation methods. This paper focused on analyzing the dispersion characteristics of hydrogen leaked from hydrogen fuel cell vehicles (HFCVs) within these environments, with particular attention given to the influence of leakage direction—upward, horizontal, and downward—on hydrogen concentration distribution over space and time. For instance, it was observed that under equivalent flow rates, upward leakage tends to result in higher hydrogen concentrations at the leakage site. Conversely, downward leakage promotes wider hydrogen diffusion around the source, particularly evident at higher flow rates. Horizontal leakage, comparatively, exhibits lower risk due to greater air volume absorption. Complementing the experimental data, numerical simulations revealed consistent patterns in hydrogen diffusion. Specifically, the simulations illustrated a cyclic accumulation-diffusion-accumulation process. Notably, vertical upward leakage demonstrated the largest volume of regions exceeding a 4 % hydrogen volume fraction, whereas vertical downward leakage resulted in the greatest volume of regions surpassing an 18.3 % hydrogen volume fraction. This disparity arises from hydrogen accumulation beneath the vehicle in cases of vertical downward leakage. Conversely, regions of high concentration induced by horizontal leakage were the smallest. The study offers valuable insights for the design and construction of HFCVs and parking facilities, providing a theoretical framework for enhancing safety measures.

Strain path dependent dynamic recrystallization and its resulted material flow and microstructure evolution of a titanium alloy

Changing strain path is an effective method to optimize the hot working process and improve microstructure and mechanical performance of titanium alloys. In this work, dynamic recrystallization (DRX) and its resulted material flow and microstructural behaviors in monotonic torsion (MT) and forward-reverse torsion (FRT) were comparatively explored by experimental and crystal plastic finite element simulation methods. The results indicate that both MT and FRT can induce discontinuous DRX (DDRX) and continuous DRX (CDRX). However, compared to MT where CDRX always prevails, FRT makes DDRX more important since it inhibits CDRX by recovering the lattice rotation during the reversal stage. Moreover, in FRT, the driving force and the grain boundary content for DDRX nucleation and bulging are relatively low at a small total strain. And the recovery of lattice rotation in FRT can also suppress CDRX. Therefore, DRX kinetics is obviously delayed at a smaller strain. As strain increases, both the stored energy for DDRX and the long-range misorientation gradient for CDRX are gradually greater, thus improve DRX kinetics. With these effects by DRX, although FRT exhibits a lower grain refinement degree at a smaller total strain compared to MT, it can make grain refinement degree rapidly rise and even close to that in MT at a greater strain. Also, FRT can obviously weaken the deformation texture by inducing extensive DDRX grains and recovering the lattice rotation of retained grains. In addition, the texture formed in forward stage and DRX delaying can result in a decrease in yield strength and softening rate in reversal stage, respectively, i.e., exhibiting remarkable Bauschinger effect, especially at a higher forward strain. These results can provide a basic guidance for designing the hot working process of titanium alloys to obtaining more refined microstructure and excellent properties of the components.

Reducing the Rebound Effect in Microscale Laser Dynamic Forming through Multi-Pulse Laser Shock Loading

Microscale laser dynamic forming, as a novel high-speed microforming technique, can overcome the shortcomings of traditional microforming methods. However, in practical applications, laser dynamic microforming technology is often affected by the rebound behavior of the workpiece, limiting the further improvement of processing quality and efficiency. This paper aims to reduce the rebound effect in laser dynamic forming by using multi-pulse laser shock loading. The forming results of workpieces under different laser energies and laser impact numbers were studied using experimental and numerical simulation methods. After multiple laser shocks, numerical simulations of the forming results were conducted using ANSYS/LS-DYNA software. These numerical simulation results were then experimentally validated and compared. The surface morphology of the workpieces was characterized using a confocal microscope and a scanning electron microscope (SEM). Energy-dispersive spectroscopy (EDS) was used to analyze the chemical element content changes in the collision regions at the bottoms of the workpieces after multi-pulse loading. The SEM and EDS results revealed the collision behavior patterns during the forming process. Finally, the forming laws of workpieces under multiple laser shocks were summarized.

Comparison of mineral transformation in CO2 geological storage under CO2–water–sandstone and mudstone reactions

Carbon dioxide (CO2) mineral trapping was considered the most secure and stable mechanism for CO2 geological storage. The previous studies lacked clarity regarding the mechanisms and processes of transformation for various types of minerals involved in CO2–water–sandstone and mudstone reactions during CO2 geological storage. Additionally, it didn't clear the different stages of mineral reactions in reservoir and caprock. We utilized experimental and numerical simulation methods to analyze the mechanisms, processes, and stages of CO2–water–rock reactions involving various types of minerals in the mudstone from Chang 4 + 5 members and the sandstone from Chang 6 member of the Triassic Yanchang Formation in the Ordos Basin. The experimental simulation demonstrated the dissolution of feldspar minerals in sandstone led to precipitate of carbonate, clay, and other minerals. Contrary, mudstone primarily underwent the dissolution of clay minerals and the precipitation of feldspar minerals, whereas carbonate content remained relatively stable. The numerical simulation consisted of experimental results in the short term, but over a longer timescale, The reaction processes of carbonate and clay minerals in the reservoir and caprock dissolved first and then precipitated. Conversely, other minerals behaved oppositely; feldspar minerals continuously dissolved in the reservoir but precipitated first and then dissolved in the caprock. The reaction stages of mineral change in both the reservoir and caprock could be divided into dissolution, rapid precipitation, and stable precipitation. The reservoir's dissolution stage was shorter than the caprock, which entered the stable precipitation stage earlier. With increasing storage time, continuous CO2–water–rock reactions gradually transformed physically sequestered CO2 in the formation into chemically sequestered mineralized CO2.