Three-dimensional coupled simulation method for aerosol across small and medium scale transient migration process

Abstract

The present application relates to a three-dimensional coupling simulation method for aerosol across small and medium scale transient migration process, and solves the problem that the existing research method is difficult to consider aerosol across scale coupling simulation. The present application comprises the following steps: 1) determining the small scale aerosol particle size group characteristics; 2) dispersing the small scale aerosol space region into a plurality of three-dimensional control bodies; 3) determining the particle number of each particle size channel in each three-dimensional control body; 4) obtaining the redistribution data of the particle number in the three-dimensional control body; 5) obtaining the aerosol mass through the redistribution data; 6) matching and mapping the small three-dimensional control body with the space grid in the medium scale range and reconstructing; 7) to 9) dividing the aerosol into different modes in the medium scale range, and calculating the mass concentration, number concentration, zero order moment, three order moment and median particle size of different modes; 10) substituting the obtained data into the medium scale numerical calculation model, and finally obtaining the parameter distribution data of the aerosol in the medium scale range.

Description

Technical Field

[0001] This invention relates to numerical calculation of aerosols, specifically to a three-dimensional coupled simulation method for transient migration processes of aerosols across small and medium scales. Background Technology

[0002] The study of transient migration of aerosols in the atmosphere is of great significance in research fields such as chemical processes, air pollution control, and even infectious disease prevention.

[0003] From the perspective of aerosol formation, atmospheric aerosols generally undergo physical stages such as source term generation, development, diffusion, and deposition. Typically, the source term generation and development stages of atmospheric aerosols exhibit typical small-scale spatial characteristics, while the diffusion and deposition of atmospheric aerosols may fall within the scope of mesoscale research. Therefore, the transient migration of atmospheric aerosols is a typical problem spanning both small and mesoscale scales.

[0004] At present, the study of aerosol migration process in the atmosphere can be mainly divided into two categories: experimental observation and numerical simulation. Among them, experimental observation is mostly conducted indoors (refer to [1] Zhang Yanzhe, Xiao Kaitao, Song Weiwei, Qin Jian, Chi Hui, Huang Ruiyuan. Indoor explosion diffusion test of riot control projectile and prediction of irritant concentration [J]. Blasting, 2021, 38(4): 163-172; [2] Li Jiangcun, Liu Zhilong, Liang Ting, Tian Xingtao, Wang Yue, Li Jigang, Dang Shengnan, Li Ting. A method for toxic substance diffusion test under explosion action, invention patent, CN112304812A, 2021.2; [3] Li Jiangcun, Liu Zhilong, Liang Ting, Tian Xingtao, Wang Yue, Li Jigang, Li Ting. A toxic substance diffusion test device under explosion action, utility model, CN213600539U, 2021.7) or outdoors (refer to Gong Pengbin, Guo Huiping, Duan Zhongshan. Simulation and experiment of spatiotemporal distribution of explosion smoke cloud diffusion, Journal of Rocket Force Engineering University (Natural Science Edition), 2019, (4).) under ideal test conditions, using experimental devices such as high-speed photography and pressure sensors to measure the spatiotemporal distribution of aerosol concentration, and by changing observation conditions such as wind speed, the influence of different factors on aerosol diffusion and deposition is studied. However, this type of experimental observation research is expensive and has poor repeatability. In addition, due to the technical limitations of existing observation instruments, the observation data that can be obtained is also relatively limited. Therefore, another major research method, namely numerical simulation, has developed rapidly in recent years and has become one of the effective means to study the spatiotemporal distribution of aerosol products.In this type of method, researchers mostly use various numerical models to study the diffusion and deposition characteristics of aerosols at different scales (refer to [1] He Fan, He Kaikai, Huang Dong, et al. Analysis of the influence of wind on the diffusion characteristics of a certain type of explosive tear gas [J]. Journal of Ordnance Engineering College, 2016, 28(5): 25-29. DOI: 10.3969 / j.issn.1008-2956.2016.05.006; [2] Shi Baojun, Nie Shiming, Sun Jing. Study on LPG leakage diffusion based on Gaussian plume mixing model [J]. Journal of Safety and Environment, 2022, 22(2): 909-918; [3] Brandt, J., Christensen, JH, and Frohn, LM: Modelling transport and deposition of caesium and iodine from the Chernobyl accident using the DREAM model, Atmos. Chem. Phys., 2, 397–417, 2002; [4] V. Simsek, L. Pozzoli, A. Unal, T. Kindap, M. Karaca. Simulation of 137Cs transport and deposition after the chernobylnuclear power plant accident and radiological doses over the Anatolian peninsula. Sci. Total Environ., 499 (2014), pp. 74-88.). Numerical simulation can be used to obtain the three-dimensional spatiotemporal distribution characteristics of aerosol concentration at different physical stages, thus providing strong technical support for the assessment of aerosol atmospheric pollution characteristics. The advantages of numerical simulation are mainly that it saves manpower and material resources, and can repeat numerical experiments multiple times. However, considering the differences in scale effects and scale characteristics of aerosols at different physical stages, from a methodological perspective, current numerical simulation methods, which generally use a single numerical model to conduct single-scale analysis of aerosols, can no longer meet the needs of simulation analysis of atmospheric aerosols' cross-scale transient migration, and their calculation accuracy and precision have certain deviations.

[0005] Overall, there is a lack of research on the three-dimensional transient migration characteristics of aerosols across small and medium scales, and conducting relevant research is of great significance for understanding the atmospheric migration process of aerosols. Summary of the Invention

[0006] This invention proposes a three-dimensional coupled simulation method for the transient migration process of aerosols across small and medium scales, which solves the problem that existing methods using a single scale cannot meet the current research needs, and the technical problem that existing research methods are difficult to consider for cross-scale coupled simulation of aerosols.

[0007] The concept of this invention is to deeply couple the source term development stage and the diffusion and deposition stage of aerosols, thereby performing cross-scale coupled simulation calculations of aerosol migration processes such as diffusion and deposition in the atmosphere. This invention first calculates the changes of aerosols in a small spatial area based on a small-scale model to obtain their concentration distribution characteristics. Then, aerosol particles are divided into different modal intervals, and the aerosol number concentration and mass concentration under different modes are obtained by calculating the step moment parameters of different modal intervals, serving as the initial conditions for mesoscale calculations. Finally, key aerosol parameters, including median particle size and standard deviation, are further calculated to meet the conditions for subsequent mesoscale calculations, thus achieving the organic integration of cross-scale numerical simulations of aerosols.

[0008] To achieve the above objectives, the technical solution of the present invention is as follows:

[0009] A three-dimensional coupled simulation method for transient migration processes of aerosols across small and medium scales is characterized by the following steps:

[0010] Step 1: Determine the aerosol density, aerosol particle size clustering characteristics, and the number of aerosol particles in each aerosol particle size cluster within the small-scale aerosol space.

[0011] Aerosols are divided into N particle size channels according to their particle size, and each particle size channel is numbered i, i = 1, 2, ..., N;

[0012] Step 2: Discretize the small-scale aerosol spatial computation region into M three-dimensional control volumes, each of which is numbered j, j = 1, 2, ..., M;

[0013] Step 3: Determine the number of particles n' in each particle size channel within each three-dimensional control volume by using the initial distribution location and mass concentration of the aerosol in three-dimensional space. i , i = 1, 2, ..., N;

[0014] Step 4, determine the number of particles n' within each particle size channel of each three-dimensional control volume. i Data on the particle size and positional distribution of aerosols were obtained, and then the redistribution data of the number of particles within each particle size channel in each three-dimensional control body were labeled as n. i,j ;

[0015] Step 5: Based on the redistribution data n of the number of particles within each particle size channel in each three-dimensional control body. i,j The aerosol mass m of each particle size channel within each three-dimensional control volume was obtained. i,j ;

[0016] Step 6: Set up a mesoscale aerosol spatial numerical calculation model, and match, map and reconstruct the three-dimensional control volume in the small-scale aerosol space with the spatial mesh of the mesoscale aerosol spatial numerical calculation model.

[0017] Step 7: In the mesoscale aerosol spatial numerical calculation model, all aerosols are divided into different modes, and the mass concentration and number concentration of different modes are calculated.

[0018] Step 8: Based on the mass concentration and number concentration of different modes obtained in Step 7, obtain the zeroth moment and third moment of the corresponding mode;

[0019] Step 9: Obtain the median particle size of aerosols of different modalities;

[0020] Step 10: Substitute the mass concentration and number concentration, zero-order moment and third-order moment of different modes and the corresponding median particle size into the mesoscale aerosol spatial numerical calculation model to finally obtain the physical parameter distribution data of aerosols in the mesoscale range.

[0021] Furthermore, step 4 is detailed below:

[0022] By embedding a population equilibrium model into the Euler multiphase solver, after solving the Navier-Stokes equations to obtain the total aerosol phase fraction, an additional set of population equilibrium equations concerning the evolution of aerosol particles is solved, taking into account the number of particles n' in each particle size channel within each three-dimensional control volume. i Data on the particle size and positional distribution of aerosols are obtained, and then the redistribution data of the number of particles in the i-th particle size channel within the j-th three-dimensional control body are labeled as n. i,j .

[0023] Furthermore, in step 5, the aerosol mass m of the i-th particle size channel inside the j-th three-dimensional control volume is calculated. i,j The formula is as follows:

[0024]

[0025] Where, n i,j Here, ρ represents the redistribution of the number of particles within the i-th particle size channel in the j-th three-dimensional control body, where ρ is the density of the aerosol, and d... i Let be the particle size of the aerosol in the i-th particle size channel.

[0026] Furthermore, step 6 is detailed below:

[0027] 6.1 Organize the aerosol data obtained from the small-scale aerosol spatial calculation method in steps 1 to 5 into a three-dimensional dataset;

[0028] 6.2 The aerosol dataset in the small-scale aerosol space is resampled using the nearest neighbor interpolation method. The resampled data overwrites the data in the original three-dimensional dataset and forms a new three-dimensional dataset. The size of the grid of the new three-dimensional dataset is adjusted to be consistent with the grid size of the three-dimensional dataset in the mesoscale aerosol space.

[0029] 6.3 Align the new 3D dataset in the small-scale aerosol space with the 3D dataset in the mesoscale aerosol space to ensure that the origin and grid spacing of the two 3D datasets are the same;

[0030] 6.4 When the origin and grid spacing are the same, the aerosol mass in the small-scale aerosol space and the number of particles in each particle size channel inside each three-dimensional control volume are fused with the spatial grid in the medium-scale aerosol space.

[0031] Further, step 7 is as follows: In the mesoscale aerosol space, according to the atmospheric aerosol three-mode theory, all aerosol particles in the N particle size channels are divided into 3 particle size intervals according to the aerosol particle size.

[0032] The particle size sub-range 1 represents the nuclear mode, in which the particle size of aerosol particles is concentrated between (0~100nm], and there are a small particle size channels in this range;

[0033] The particle size sub-range 2 represents the accumulation mode. The particle size of aerosol particles in this range is concentrated between 100 nm and 1 μm. There are a total of b small particle size channels in this range.

[0034] The particle size range 3 represents the coarse mode, in which the particle size of aerosol particles is concentrated between (1μm~10μm), and there are a total of c small particle size channels in this range;

[0035] For each mode, calculate its aerosol mass concentration and number concentration.

[0036] Furthermore, the formula for calculating the aerosol mass concentration is as follows:

[0037]

[0038]

[0039]

[0040] Among them, M k1 It is the mass of nuclear modal aerosol particles, M k2It is the mass of the accumulated modal aerosol particles, M k3 It is the mass of the coarse-mode aerosol particles, m i Ni is the mass of the particle in the i-th particle size channel, Ni is the number of particles in the i-th particle size channel, and i is the particle size channel number in the small-scale model.

[0041] The formula for calculating number concentration is as follows:

[0042]

[0043]

[0044]

[0045] Where, N k1 It is the number of nuclear modal aerosol particles, N k2 It is the number of aerosol particles in the accumulation mode, N k3 Ni is the number of coarse-mode aerosol particles, and Ni is the number of particles in the i-th particle size channel.

[0046] Furthermore, in step 8, the formulas for calculating the zeroth moment under different modes are as follows:

[0047] M0 k1 =N k1

[0048] M0 k2 =N k2

[0049] M0 k3 =N k3

[0050] Among them, M0 k1 It is the zero-order moment of the nuclear modal aerosol particle, M0 k2 It is the zero-order moment of the accumulated modal aerosol particles, M0 k3 It is the zero-order moment of the coarse-mode aerosol particles, N k1 It is the number of nuclear modal aerosol particles, N k2 It is the number of aerosol particles in the accumulation mode, N k3 It refers to the number of coarse-mode aerosol particles;

[0051] The formulas for calculating the third moment under different modes are as follows:

[0052]

[0053]

[0054]

[0055] Among them, M3 k1It is the third moment of the nuclear modal aerosol particle, M3 k2 It is the third moment of the accumulated modal aerosol particles, M3 k3 It is the third moment of the coarse-mode aerosol particles, M k1 It is the mass of nuclear modal aerosol particles, M k2 It is the mass of the accumulated modal aerosol particles, M k3 ρ is the mass of the coarse-mode aerosol particles, and ρ is the density of the aerosol.

[0056] Furthermore, in step 9, the formula for calculating the median particle size of different modal aerosols is as follows:

[0057]

[0058]

[0059]

[0060] Where, μ k1 It is the median particle size of nuclear modal aerosol particles, μ k2 It is the median particle size of the aerosol particles in the accumulation mode, μ k3 It is the median particle size of coarse-mode aerosol particles; σ k1 It is the standard deviation of nuclear modal aerosol particles, σ k2 It is the standard deviation of the accumulated modal aerosol particles, σ k3 It is the standard deviation of coarse-mode aerosol particles, σ k1 The value is 1.7, σ k2 The value is 2.0, σ k3 The value is 2.2.

[0061] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0062] (1) This invention provides a three-dimensional coupling simulation method for aerosols across small and medium scales, which can realize the three-dimensional dynamic calculation of the development and generation stage of aerosol source terms in the small scale range and the three-dimensional matching of aerosol parameters between the calculation of aerosol diffusion and deposition in the medium scale range, thereby realizing the organic data coupling of aerosol numerical calculation across scales.

[0063] (2) This invention provides a three-dimensional coupled simulation method for aerosols across small and medium scales. The spatial resolution can be organically adjusted according to the differences in the spatial scale of the computational domain, thereby realizing the transformation of spatial scale: For aerosol calculations in the small scale range, the spatial resolution can reach the meter level because it is necessary to accurately characterize the three-dimensional dynamic characteristics of aerosols; after transitioning to the medium scale stage, for aerosol transport, migration and deposition calculations in the medium scale range, the spatial resolution can reach 1 to 3 km based on comprehensively considering the influence of complex factors such as meteorology and topography on the calculation results.

[0064] (3) This invention provides a three-dimensional coupled simulation method for aerosols across small and medium scales, which effectively solves the problem that the dynamic changes of aerosol source terms in the generation and development stages in small scales cannot be accurately described in mesoscale calculations, and also solves the problem that the simulation of aerosol diffusion and sedimentation characteristics in mesoscales cannot be described in small-scale calculations. Attached Figure Description

[0065] Figure 1 This is a schematic diagram of the process of the present invention. Detailed Implementation

[0066] The present invention will be further described below with reference to specific embodiments and accompanying drawings.

[0067] It is generally believed that a horizontal spatial scale within 10 km is a typical small-scale range, while a horizontal spatial scale exceeding 100 km is a typical medium-scale range.

[0068] A three-dimensional coupled simulation method for transient migration processes of aerosols across small and medium scales is described below. Figure 1 As shown, the specific steps are as follows:

[0069] Step 1: Determine key information of source term parameters in small-scale aerosol space, including aerosol density, aerosol particle size clustering characteristics, and the number of aerosol particles in each aerosol particle size cluster.

[0070] Let the density of the aerosol be ρ, and the aerosol be divided into N particle size channels according to different particle sizes, each channel being numbered i (i = 1, 2, ..., N). Since all aerosol particles within each channel have the same size, d i (i = 1, 2, ..., N) represents the aerosol particle size in the i-th particle size channel. The total number of aerosol particles in the i-th particle size channel is n. i (i = 1, 2, ..., N). The particle size of the aerosol is no greater than 10 μm.

[0071] Step 2: Discretize the computational domain of the entire small-scale aerosol space into M three-dimensional control volumes, each of which is numbered j (j = 1, 2, ..., M).

[0072] Step 3: By determining the initial distribution position and mass concentration of aerosol particles in three-dimensional space, the number of particles in the i-th particle size channel within each three-dimensional control volume is determined, which can be denoted as n'. i (i = 1, 2, ..., N).

[0073] Step 4: In the dynamic calculation of small-scale aerosol space, a population equilibrium model is implanted into the Euler multiphase solver. After solving the Navier-Stokes equations to obtain the total aerosol phase fraction, an additional set of population equilibrium equations concerning the evolution of aerosol particles is solved, using the particle number n'. i By obtaining data on aerosol particle size and positional distribution, the redistribution data of the number of particles in the i-th particle size channel within the j-th three-dimensional control body can be labeled as n. i,j .

[0074] Step 5, based on the redistribution data n of each particle size channel within each three-dimensional control volume. i,j The aerosol mass m of the i-th particle size channel inside the j-th three-dimensional control volume is calculated. i,j The specific calculation formula is as follows:

[0075]

[0076] Step 6: Match, map, and reconstruct the three-dimensional control volume of the small-scale aerosol spatial calculation method with the spatial mesh of the mesoscale aerosol spatial numerical calculation model.

[0077] 6.1 Organize the aerosol data obtained from the small-scale aerosol spatial calculation method in steps 1 to 5 into a three-dimensional dataset;

[0078] 6.2 The aerosol dataset in the small-scale aerosol space is resampled using the nearest neighbor interpolation method. The resampled data overwrites the data in the original three-dimensional dataset and forms a new three-dimensional dataset. The grid size of the new three-dimensional dataset is adjusted to be the same as that of the three-dimensional dataset in the mesoscale aerosol space.

[0079] 6.3 Align the new 3D dataset in the small-scale aerosol space with the 3D dataset in the mesoscale aerosol space to ensure that the origin and grid spacing of the two 3D datasets are the same;

[0080] 6.4 After ensuring that the origin and grid spacing are the same, the aerosol mass in the small-scale aerosol space and the number of particles in each particle size channel inside each three-dimensional control volume are fused with the spatial grid in the medium-scale aerosol space.

[0081] Step 7: Define the numbering of each spatial grid as j* (j*=1,2,......,M) in the mesoscale aerosol space. *For any spatial grid in mesoscale aerosol space, according to the three-mode theory of atmospheric aerosols, all aerosol particles within N particle size channels can be divided into three particle size sub-intervals based on their aerosol particle size. Sub-interval 1 represents the nucleus mode, where aerosol particles are concentrated between 0 and 100 nm in size, and contains *a* small particle size channels. Sub-interval 2 represents the accumulation mode, where aerosol particles are concentrated between 100 nm and 1 μm in size, and contains *b* small particle size channels. Sub-interval 3 represents the coarse mode, where aerosol particles are concentrated between 1 μm and 10 μm in size, and contains *c* small particle size channels. Each particle size sub-interval can be considered to represent one aerosol mode. For a given aerosol data with a finer particle size allocation, it is divided into particle size ranges corresponding to the three modes, and the quality and quantity of data within each range are statistically analyzed. For each mode, calculate its aerosol mass concentration and number concentration.

[0082] The following formula can be used to calculate the mass concentration of a certain mode:

[0083]

[0084]

[0085]

[0086] Where M k1 It is the mass of nuclear modal aerosol particles, M k2 It is the mass of the accumulated modal aerosol particles, M k3 It is the mass of the coarse-mode aerosol particles, m i Ni is the mass of the particle in the i-th particle size channel, Ni is the number of particles in the i-th particle size channel, and i is the particle size channel number in the small-scale model.

[0087] The formula for calculating number concentration is as follows:

[0088]

[0089]

[0090]

[0091] Where N k1 It is the number of nuclear modal aerosol particles, N k2 It is the number of aerosol particles in the accumulation mode, N k3 Ni is the number of coarse-mode aerosol particles, and Ni is the number of particles in the i-th particle size channel.

[0092] Step 8, for the above mesoscale spatial grid j *Based on the mass concentration and number concentration calculation results of each mode obtained in step 7, the zero-order moment and third-order moment of the aerosol of that mode can be further calculated.

[0093] M0 k1 =N k1

[0094] M0 k2 =N k2

[0095] M0 k3 =N k3

[0096] M0 k1 It is the zero-order moment of the nuclear modal aerosol particle, M0 k2 It is the zero-order moment of the accumulated modal aerosol particles, M0 k3 It is the zero-order moment of the coarse-mode aerosol particles.

[0097]

[0098]

[0099]

[0100] M3 k1 It is the third moment of the nuclear modal aerosol particle, M3 k2 It is the third moment of the accumulated modal aerosol particles, M3 k3 It is the third moment of the coarse-mode aerosol particles.

[0101] Step 9: Assuming that aerosols in different modes follow a log-normal distribution, and based on the principles of aerosol mass and quantity conservation, the median particle size of aerosols in different modes is obtained using the following formula:

[0102]

[0103]

[0104]

[0105] Where μ k1 It is the median particle size of nuclear modal aerosol particles, μ k2 It is the median particle size of the aerosol particles in the accumulation mode, μ k3 It is the median particle size of coarse-mode aerosol particles; σ k1 It is the median standard deviation of nuclear modal aerosol particles, σ k2 It is the standard deviation of the accumulated modal aerosol particles, σ k3 It represents the standard deviation of coarse-mode aerosol particles. Where σ k1The value is 1.7, where σ k2 The value is 2.0, where σ k3 The value is 2.2.

[0106] Step 10: The calculation process of steps 7, 8, and 9 is repeated through all spatial grids in the mesoscale aerosol space to obtain the mass concentration, number concentration, zero-order moment, third-order moment, and median particle size of different modes of aerosols in all spatial grids.

[0107] Step 11: Substitute the calculation data obtained in step 10 into the mesoscale model to perform diffusion and sedimentation calculations based on the multimodal aerosol model under mesoscale conditions.

[0108] The above calculations can yield the three-dimensional dynamic distribution and variation process of aerosols with different particle sizes, and obtain dynamic distribution data of aerosol spatial concentration. This data can then be used to further calculate the dynamic deposition characteristics of aerosols on the Earth's surface. This data can provide valuable support for air quality assessment and atmospheric pollution consequence assessment.

Claims

1. A three-dimensional coupled simulation method for transient migration processes of aerosols across small and medium scales, characterized in that, Includes the following steps: Step 1: Determine the aerosol density, aerosol particle size clustering characteristics, and the number of aerosol particles in each aerosol particle size cluster within the small-scale aerosol space. Aerosols are classified according to their particle size into There are several particle size channels, each numbered as follows: ; Step 2: Discretize the small-scale aerosol spatial computational region into There are three-dimensional control volumes, each numbered as follows: ; Step 3: Determine the number of particles in each particle size channel within each three-dimensional control volume by using the initial distribution location and mass concentration of the aerosol in three-dimensional space. ; Step 4: Count the number of particles within each particle size channel of each three-dimensional control volume. Data on the particle size and positional distribution of aerosols were obtained, and then the redistribution data of the number of particles within each particle size channel in each three-dimensional control body were labeled as follows. Specifically: By embedding a population equilibrium model into the Euler multiphase solver, after solving the Navier-Stokes equations to obtain the total aerosol phase fraction, an additional set of population equilibrium equations concerning the evolution of aerosol particles is solved, based on the number of particles in each particle size channel within each three-dimensional control volume. Data on the particle size and positional distribution of aerosols are obtained, and then the redistribution data of the number of particles in the i-th particle size channel within the j-th three-dimensional control body are labeled as follows. ; Step 5: Based on the redistribution data of the number of particles within each particle size channel in each three-dimensional control body. Obtain the aerosol mass of each particle size channel within each three-dimensional control volume. ; Step 6: Set up a mesoscale aerosol spatial numerical calculation model, and match, map and reconstruct the three-dimensional control volume in the small-scale aerosol space with the spatial mesh of the mesoscale aerosol spatial numerical calculation model. Step 7: In the mesoscale aerosol spatial numerical calculation model, all aerosols are divided into different modes, and the mass concentration and number concentration of different modes are calculated. Step 8: Based on the mass concentration and number concentration of different modes obtained in Step 7, obtain the zeroth moment and third moment of the corresponding mode; Step 9: Obtain the median particle size of aerosols of different modalities; The formulas for calculating the median particle size of aerosols of different modalities are as follows: 、 、 ； in, It is the median particle size of nuclear modal aerosol particles. It is the median particle size of the aerosol particles in the accumulation mode. It is the median particle size of coarse-mode aerosol particles; It is the standard deviation of nuclear mode aerosol particles. It is the standard deviation of the accumulated modal aerosol particles. It is the standard deviation of coarse-mode aerosol particles. The value is 1.

7. The value is 2.

0. The value is 2.2; It is the third moment of the nuclear modal aerosol particles. It is the third moment of the accumulated modal aerosol particles. It is the third moment of the coarse-mode aerosol particles; It is the zero-order moment of nuclear mode aerosol particles. It is the zero-order moment of the accumulated modal aerosol particles. It is the zero-order moment of the coarse-mode aerosol particles; Step 10: Substitute the mass concentration and number concentration, zero-order moment and third-order moment of different modes and the corresponding median particle size into the mesoscale aerosol spatial numerical calculation model to finally obtain the physical parameter distribution data of aerosols in the mesoscale range.

2. The three-dimensional coupled simulation method for transient migration processes of aerosols across small and medium scales according to claim 1, characterized in that, In step 5, the aerosol mass of the i-th particle size channel inside the j-th three-dimensional control volume is calculated. The formula is as follows: ； in, This represents the redistribution data of the number of particles within the i-th particle size channel within the j-th three-dimensional control body. The density of the aerosol. Let be the particle size of the aerosol in the i-th particle size channel.

3. The three-dimensional coupled simulation method for transient migration processes of aerosols across small and medium scales according to claim 2, characterized in that, Step 6 is as follows: Step 6.1: Organize the aerosol data obtained from the small-scale aerosol spatial calculation methods in Steps 1 to 5 into a three-dimensional dataset; Step 6.2: Resample the aerosol dataset in the small-scale aerosol space using the nearest neighbor interpolation method. The resampled data overwrites the data in the original three-dimensional dataset and forms a new three-dimensional dataset. Adjust the grid size of the new three-dimensional dataset to be consistent with the grid size of the three-dimensional dataset in the mesoscale aerosol space. Step 6.3: Align the new 3D dataset in the small-scale aerosol space with the 3D dataset in the meso-scale aerosol space to ensure that the origin and grid spacing of the two 3D datasets are the same. Step 6.4: When the origin and grid spacing are the same, the aerosol mass in the small-scale aerosol space and the number of particles in each particle size channel inside each three-dimensional control volume are fused with the spatial grid in the medium-scale aerosol space.

4. The three-dimensional coupled simulation method for aerosol across meso-small scale transient migration processes according to any one of claims 1-3, characterized in that, Step 7 is specifically as follows: in the mesoscale aerosol space, according to the atmospheric aerosol three-mode theory, all aerosol particles in one particle size channel are divided into three particle size small intervals according to the aerosol particle size; ​ The particle size sub-range 1 represents the nuclear mode. The particle size of aerosol particles in this range is concentrated between (0~100nm). There are a small particle size channels in this range. The particle size sub-range 2 represents the accumulation mode. The particle size of aerosol particles in this range is concentrated between 100 nm and 1 μm. There are a total of b small particle size channels in this range. The particle size sub-range 3 represents the coarse mode, in which the particle size of aerosol particles is concentrated between (1μm~10μm), and there are a total of c small particle size channels in this range; For each mode, calculate its aerosol mass concentration and number concentration.

5. The three-dimensional coupled simulation method for transient migration processes of aerosols across small and medium scales according to claim 4, characterized in that, The formula for calculating aerosol mass concentration is as follows: 、 、 ； in, It is the mass of nuclear modal aerosol particles. It is the mass of the accumulated modal aerosol particles. It is the mass of coarse-mode aerosol particles. Ni is the mass of the particle in the i-th particle size channel, Ni is the number of particles in the i-th particle size channel, and i is the particle size channel number in the small-scale model. The formula for calculating number concentration is as follows: 、 、 ； in, It refers to the number of nuclear modal aerosol particles. It is the number of aerosol particles in the accumulation mode. Ni is the number of coarse-mode aerosol particles, and Ni is the number of particles in the i-th particle size channel.

6. The method for three-dimensional coupled simulation of aerosol across meso small scale transient migration processes according to claim 5, characterized in that, In step 8, the formulas for calculating the zeroth moment under different modes are as follows: 、 、 ； wherein, is the number of nucleation mode aerosol particles, is the number of accumulation mode aerosol particles, is the number of coarse mode aerosol particles; The formulas for calculating the third moment under different modes are as follows: 、 、 ； in It is the mass of nuclear modal aerosol particles. It is the mass of the accumulated modal aerosol particles. It is the mass of coarse-mode aerosol particles. This represents the density of the aerosol.

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