CN-121980888-A - Method, system and storage device for simulating cross-region diffusion of particulate matters under dynamic boundary

CN121980888ACN 121980888 ACN121980888 ACN 121980888ACN-121980888-A

Abstract

The invention discloses a method, a system and a storage device for simulating cross-region diffusion of particulate matters under a dynamic boundary, and relates to the field of environmental monitoring. The method comprises the steps of establishing a multi-region full-size three-dimensional geometric model comprising tunnels and stations, meshing the model, processing boundary changes caused by train movement, solving a flow field to obtain a dynamic speed field under the train movement, establishing an improved slip flux model to solve a particulate matter transportation equation, setting transient simulation boundary conditions, and solving concentration distribution and cross-region diffusion conditions of particulate matters with different particle sizes according to the dynamic speed field through the particulate matter transportation equation. According to the invention, the simulation time is greatly reduced, the calculation memory is saved, the simulation accuracy of the particulate matters with different physical properties is improved, and the migration behaviors of the particulate matters in different areas are accurately represented by dynamic boundary conditions.

Inventors

JI WENJING
SHI ZHICHENG
CHEN TINGYUE
ZHAO XINYI
LIU JING

Assignees

北京科技大学

Dates

Publication Date: 20260505
Application Date: 20260113

Claims (10)

1. A method for simulating cross-regional diffusion of particulate matter under dynamic boundary conditions, the method comprising: S1, establishing a multi-region full-size three-dimensional geometric model comprising a tunnel and a station, wherein the station comprises a platform and a station hall, and the tunnel covers a train motion path; S2, carrying out grid division on the geometric model, and adopting a dynamic layered grid technology to process boundary change caused by train movement in a train movement area; s3, solving a flow field based on a Reynolds average Navier-Stokes equation and a standard k-epsilon turbulence model to obtain a dynamic speed field under the movement of the train; S4, establishing an improved slip flux model to solve a particulate matter transport equation, wherein the improved slip flux model considers the difference of slip speeds and vortex diffusion coefficients of particulate matters with different particle diameters; S5, setting a boundary condition of transient simulation, wherein the boundary condition covers a train running curve, station entrance and exit pressure and a strong particulate matter source; and S6, solving concentration distribution and cross-region diffusion conditions of the particles with different particle diameters according to the dynamic speed field through a particle transport equation.
2. The method for simulating cross-regional diffusion of particulate matter under dynamic boundary conditions according to claim 1, wherein in S1, establishing a multi-region full-size three-dimensional geometric model including a tunnel and a station comprises: the tunnel comprises a complete length between front and rear adjacent stations; the multi-region full-size three-dimensional geometric model covers tunnels, platforms, station halls, entrances and exits and stair regions.
3. The method for simulating cross-regional diffusion of particulate matter under dynamic boundary conditions according to claim 2, wherein in S1, the multi-region full-size three-dimensional geometric model is a full-size refined three-dimensional station-tunnel model, and the full-size refined three-dimensional station-tunnel model is consistent with an actual station.
4. The method for simulating cross-regional diffusion of particulate matter under dynamic boundary conditions according to claim 1, wherein S2 specifically comprises: S21, carrying out grid division on a train movement area, wherein a structured grid is adopted for an area nearby a train body and a tunnel; S22, dividing the non-train movement area into a regular area and an irregular area, adopting a structured grid for the regular area and adopting an unstructured grid for the irregular area; s23, determining grid splitting and collapsing conditions based on a height method, wherein the grid size of the area near the train body is larger than the train displacement distance in a single time step.
5. The method for simulating cross-regional diffusion of particulate matter under dynamic boundary conditions according to claim 1, wherein S3 specifically comprises: s31, carrying out time average on a transient control equation, deducing a time-average continuity equation and a Reynolds average Navier-Stokes equation, and introducing a Reynolds stress term; s32, adopting a vortex viscosity model, and correlating the Reynolds stress with a vortex viscosity coefficient through a Boussinesq vortex viscosity hypothesis; s33, closing an equation set through turbulent kinetic energy k and turbulent dissipation rate epsilon by adopting a two-equation standard k-epsilon turbulent flow model; and S34, combining a continuity equation, a momentum equation, a k transportation equation and an epsilon transportation equation, solving simultaneously, and finally obtaining a standard k-epsilon turbulence model speed field and a standard pressure field.
6. The method for simulating cross-regional diffusion of particulate matter under dynamic boundary conditions of claim 1, wherein S4 specifically comprises: S41, constructing a particulate matter transport equation, and incorporating two key parameters of a slip velocity term and a corrected vortex diffusion coefficient; S42, calculating a sliding speed item and a vortex diffusion coefficient, and considering the difference of particle size and density of the particulate matters; S43, correcting a deposition flux model to consider the influence of turbulent flow on the deposition of the particles.
7. The method for simulating cross-regional diffusion of particulate matter under dynamic boundary conditions of claim 1, wherein in S5, the boundary conditions include: the train running curve comprises constant speed running, uniform deceleration station entering, station stopping, uniform acceleration station leaving and subsequent constant speed running stages; the tunnel inlet is set as a pressure inlet, the tunnel outlet, the outlet of the station leading to the outside and the air shaft in the tunnel are set as pressure outlets, and outdoor particles enter the room according to the outlet pressure value, so that the temperature influence is not considered in the whole process; The particle source comprises an outdoor particle concentration and a dynamic particle dispersion source generated by train movement.
8. The method for simulating cross-regional diffusion of particulate matter under dynamic boundary conditions of claim 1, wherein S6 specifically comprises: respectively solving a particulate matter transport equation for particulate matters in different particle size ranges; and adopting a first-order windward format discrete particulate matter transport equation and performing transient calculation on the basis of a dynamic speed field until the residual error of the control equation is converged.
9. A particulate matter cross-region diffusion simulation system under a dynamic boundary, the system comprising a processor and a memory for storing executable instructions, wherein the processor is configured to execute the executable instructions to perform the particulate matter cross-region diffusion simulation method under a dynamic boundary as claimed in any one of claims 1 to 8.
10. A computer readable storage medium having stored thereon a computer program which when executed by a processor implements the method of simulating the cross-regional diffusion of particulate matter under dynamic boundaries of any one of claims 1 to 8.

Description

Method, system and storage device for simulating cross-region diffusion of particulate matters under dynamic boundary Technical Field The invention relates to the field of environmental monitoring, in particular to a method, a system and a storage device for simulating cross-region diffusion of particulate matters under a dynamic boundary. Background The subway is used as a backbone system of urban public transportation, has the advantages of large transportation capacity, strong punctuality, comfort, convenience and the like, and becomes an important mode of daily travel of the public. The metro line mileage and the operation station in China are in the front of the world, and the annual passenger traffic volume reaches hundreds of billions. However, the subway station is generally positioned in an underground or semi-underground space, and has the characteristics of strong space closure, complex ventilation organization, various pollution sources, obvious time variation and the like, namely, multi-source coupling such as train operation, brake abrasion, wheel rail/pantograph abrasion, passenger activity dust raising, outdoor air invasion and the like, so that the concentration of particles in the station is always higher than that of particles outside the station, and partial areas can even reach a plurality of times to tens of times of outdoor concentration under specific working conditions. The health risks and the fine control demands of the particles are increasingly prominent when subway staff and passengers are in a high-frequency exposure scene. Due to the cost, accessibility and repeatability of field test, continuous and complete data are difficult to obtain in the dimensions of the whole process of entering and exiting a train, multi-region linkage, multi-particle-size particle dynamics difference and the like, so that the ventilation exchange path and the inter-region migration rule of particles in the station are difficult to systematically reveal. Therefore, the development of numerical simulation of the diffusion of the particles in the subway station is of great significance. With the development of Computational Fluid Dynamics (CFD) technology, the application of the CFD technology in the rail transit environment simulation is mature, and the unsteady airflow induced by train operation and the influence of the unsteady airflow on pollutant transportation can be reproduced under a controllable condition. The existing subway space particle simulation method mainly comprises an Euler method and a Lagrange method, wherein the Euler method is used for regarding particles as a continuous phase, concentration distribution is obtained by solving a transport equation of similar fluid, the Lagrange method is used for regarding particles as a discrete phase, particle trajectories are tracked by solving a single particle stress and motion equation, and the concentration distribution is obtained through post-treatment. However, the prior art still has the following defects, so that the accuracy and the calculation efficiency are difficult to be simultaneously considered, (1) the dynamic characteristic characterization is insufficient, the partial research approximates the particulate matters to gas scalar treatment, the key characteristics such as gravity sedimentation, particle size effect, sliding speed and the like are ignored, and the differential diffusion behaviors of the particulate matters with different particle sizes/different densities in the complex flow field of the station are difficult to be accurately described. (2) The efficiency and the precision of the discrete particle method are difficult to be compatible, namely, the Lagrangian tracking method such as a common discrete phase model (namely, DPM) is difficult to stably characterize space distribution and cross-region diffusion when the particle number is insufficient, the calculation time and the memory occupation are obviously increased when the particle number is increased, and engineering application of station dimensions, unsteady working conditions and multiple working conditions is difficult to support. (3) The boundary conditions and simulation categories are simplified, most researches adopt static boundary conditions or equivalent steady-state processing, the piston wind effect caused by train movement and the pressure/speed boundary changing along with time cannot be accurately reflected, meanwhile, research objects are often limited to single areas such as platforms or station halls, and unified modeling and quantitative evaluation on air exchange and particulate matter transregional migration among multiple areas of a station are lacked. Therefore, there is a need for a method for simulating the cross-region diffusion of particulate matters, which can realize multi-region coupling under dynamic boundary conditions and combine the reality of the dynamics of the particulate matters and the calculation efficiency, so as to