Urban ventilation corridor construction method and system based on CFD and circuit theory

Abstract

The application discloses a city ventilation corridor construction method and system based on CFD and circuit theory, and belongs to the technical field of city ecological environment planning. The method comprises data acquisition and preprocessing, including city wind speed background value and city terrain and building distribution data acquisition and processing; surface temperature inversion, surface temperature distribution data of a target region are acquired through surface temperature inversion of the target region; ventilation corridor construction suitability evaluation, a multi-factor comprehensive evaluation of ventilation corridor construction suitability of the target region is carried out; circuit simulation, current simulation of the target region is carried out by using a circuit theory tool; and ventilation corridor construction, a ventilation corridor system of the target region is constructed according to a current simulation diagram result. The application has the advantages that a city ventilation corridor identification model based on fluid dynamics and circuit theory is constructed by combining fluid motion rules and electronic random walk characteristics in a circuit; and a ventilation corridor system of a "wind source-corridor-repair area" is constructed, which is more helpful to identify city ventilation corridors and guide corridor construction practice.

Description

Technical Field

[0001] This invention relates to the field of urban ecological environment planning technology, and more specifically, to a method and system for constructing urban ventilation corridors based on CFD and circuit theory. Background Technology

[0002] Since the 1990s, my country has entered a phase of rapid urbanization, with cities maintaining high-speed development for nearly three decades. Entering the new stage of urbanization, the focus of my country's urbanization efforts has shifted from quantitative growth to qualitative improvement, with the improvement of the living environment becoming a top priority in urban construction. Therefore, constructing ventilation corridors to improve urban ventilation, reduce the intensity of the urban heat island effect, enhance thermal comfort, and alleviate smog has become an important means for urban managers to improve the living environment and enhance urban livability.

[0003] The core of ventilation corridor construction lies in wind environment research. After more than forty years of development, three technical systems have gradually emerged both domestically and internationally: physical measurement methods based on field measurements or wind tunnel experiments; direct simulation methods based on tools such as CFD and WRF; and indirect simulation methods based on ventilation potential assessment and minimum cost path algorithms. Each of these systems has relatively mature technical processes, but only the indirect simulation method based on ventilation potential assessment and minimum cost path algorithms has high operability at the urban scale. This method currently faces two main problems: First, the minimum cost path algorithm is insensitive to identifying low-level wind corridors, cannot characterize corridor width information, and has limited ability to identify potential wind corridor areas, leaving considerable room for improvement; second, existing methods mostly simulate wind corridors based on prevailing urban wind directions, ignoring the influence of the complex built environment on urban wind conditions and having limited ability to identify urban wind source areas, thus making them unsuitable for constructing more refined urban ventilation corridor systems. In summary, developing ventilation corridor construction methods has significant practical value, but the current mainstream technical systems face a dilemma between practicality and accuracy, urgently requiring improvement and refinement.

[0004] In related technologies, such as Chinese patent document CN 114021303 A, a method for intelligently excavating urban ventilation corridors based on high-precision oblique photogrammetry images is disclosed, including the following steps: Step S1: Oblique photogrammetry is used to acquire oblique photogrammetry images of the target city through aerial photography to obtain a digital surface model (DSM) and a digital elevation model (DEM); Step S2: The difference between the DSM and DEM is used to extract the three-dimensional surface data of the target city; Step S3: Multiple prevailing wind direction information of the target city is obtained, and the windward area density of each prevailing wind direction is calculated based on the three-dimensional surface data obtained in Step S2; Step S4: A template is designed based on the prevailing wind direction information, and template matching is performed based on the windward area density of the prevailing wind direction to find the continuous area within the windward area density range as urban ventilation corridors; Step S5: Based on Step S4, the urban ventilation corridors are automatically excavated to extract urban ventilation corridors that meet preset requirements. As can be seen from the above, the related technologies do not provide effective solutions to the problems of how to assess urban wind sources and how to identify potential ventilation corridors at a fine scale. Summary of the Invention

[0005] 1. Technical problems to be solved

[0006] To address the challenges in assessing urban wind sources and accurately identifying potential ventilation corridors at a fine scale in existing technologies, this invention provides a method and system for constructing urban ventilation corridors based on CFD and circuit theory. By combining fluid dynamic characteristics and electronic random walk characteristics, it provides more refined urban wind field information for ventilation corridor construction based on RS and GIS, thereby further improving the method for constructing urban ventilation corridors and better realizing the identification of urban ventilation corridors and important nodes at a fine scale.

[0007] 2. Technical Solution

[0008] The objective of this invention is achieved through the following technical solutions.

[0009] A method for constructing urban ventilation corridors based on CFD and circuit theory includes the following steps:

[0010] Data acquisition and preprocessing: Acquire data on meteorological wind speed, topography, and building distribution in the target area, and perform preprocessing.

[0011] Urban wind field mapping: The obtained urban meteorological wind speed and simplified urban 3D model are imported into CFD software to simulate the wind field and obtain the urban wind field conditions.

[0012] Land surface temperature inversion: Land surface temperature is inverted based on daytime remote sensing data to obtain the land surface temperature distribution in the target area;

[0013] Suitableness evaluation for ventilation corridor construction: Single-factor evaluation of the suitability of ventilation corridor construction in the target area is conducted, and the results of the single-factor evaluation are superimposed to obtain a multi-factor comprehensive evaluation result;

[0014] Circuit simulation: Combining the results of urban wind field and wind corridor construction suitability, circuit theory tools are used to simulate the wind environment current in the target area;

[0015] Construction of the ventilation corridor system: Based on the current simulation results, a "wind source-corridor-repair area" urban ventilation corridor system was constructed. Further, data acquisition was conducted, including digital elevation model data, remote sensing imagery data, building base maps and height vector data, road network vector data, green space and water system vector data, and multi-year wind direction and speed observation data.

[0016] Furthermore, preprocessing involves projecting and cropping the acquired geographic information data within the GIS platform, removing null values ​​from the acquired wind direction and speed data, calculating the annual average daily wind speed and wind frequency in each direction, and building a simplified 3D model of the city.

[0017] Furthermore, the preprocessing steps are as follows:

[0018] Check the data status;

[0019] Unified coordinates and extent: Project and crop the acquired data in the GIS platform to unify the projection coordinate system and extent of the data;

[0020] Calculate the wind frequency and average wind speed in each direction:

[0021]

[0022]

[0023] The cumulative daily average wind speed is N, where N is the total number of days for wind speed and direction data, and V is the average daily wind speed over the years. i Let f be the average daily wind speed on day i. α Let n be the wind frequency in direction α. α This represents the number of days in the wind direction data where the direction is α.

[0024] Furthermore, the data inspection steps specifically include: checking and processing outliers in the acquired digital elevation model (DEM) data; checking remote sensing image data; checking and processing geometric errors in the vector data of buildings, green spaces, water systems, and road networks; and removing null values ​​and other outliers from the wind direction and speed data. Further, the steps for obtaining the urban wind field include: establishing a simplified 3D urban model based on the building base map, height vector data, and DEM data; importing the simplified 3D urban model into CFD software for wind environment simulation to obtain the steady-state wind speed distribution at a specific height.

[0025] Furthermore, the specific steps for simulating wind environment using CFD software are as follows:

[0026] Preprocessing includes importing the model, establishing the solution domain, and meshing.

[0027] Solution: This includes establishing a turbulence model, setting boundary conditions, solving for steady-state conditions, and determining convergence.

[0028] Post-processing: Display simulation results using wind speed cloud maps and vector maps.

[0029] Furthermore, in the circuit simulation step, the circuit simulation results include obtaining the cumulative current, current potential, and normalized current.

[0030] Furthermore, the steps for constructing a ventilation corridor system include: interpreting the cumulative current, normalized current, and current potential results obtained from circuit simulation; and determining the air source, corridor, and restoration area and their boundaries in the urban ventilation corridor system.

[0031] The system based on the above-mentioned urban ventilation corridor construction method based on CFD and circuit theory includes:

[0032] Data acquisition and preprocessing module: Acquires data such as meteorological wind speed, topography, and building distribution in the target area, and performs preprocessing.

[0033] Urban wind field mapping module: Import the acquired urban meteorological wind speed and simplified urban 3D model into CFD software to simulate the wind field and obtain the urban wind field conditions;

[0034] Land surface temperature inversion module: Based on daytime remote sensing data, it performs land surface temperature inversion to obtain the land surface temperature distribution of the target area;

[0035] The suitability evaluation module for the construction of ventilation corridors in the target area is used to conduct a single-factor evaluation of the suitability of the construction of ventilation corridors in the target area, and the single-factor evaluation results are superimposed to obtain a multi-factor comprehensive evaluation result.

[0036] Circuit simulation module: Combining the results of urban wind field and wind corridor construction suitability, the module uses circuit theory tools to simulate wind environment current in the target area;

[0037] Ventilation corridor system construction module: Based on the current simulation results, construct an urban ventilation corridor system consisting of "wind source - corridor - repair area".

[0038] 3. Beneficial effects

[0039] Compared with existing technologies, the advantages of this invention are as follows: This solution combines fluid motion characteristics and electron random walk characteristics in circuits to construct an urban ventilation corridor identification model based on fluid dynamics and circuit theory; This solution uses CFD simulation results to evaluate the wind conditions in the target area, which can effectively obtain the range and relative intensity of the main wind sources in the target area; This solution introduces circuit theory into the simulation of potential ventilation corridors, which can better simulate secondary wind corridors in the target area, intuitively display the width of the wind corridors, and identify ventilation blockage points; The urban ventilation corridor system constructed in this way has greater application value and is more conducive to the formulation of relevant construction plans. Attached Figure Description

[0040] Figure 1 This is a flowchart of an embodiment of the urban ventilation corridor construction method based on CFD and circuit theory according to the present invention;

[0041] Figure 2 This is a simplified schematic diagram of the mountain principle according to an embodiment of the present invention;

[0042] Figure 3 This is an example diagram of a simplified 3D city model according to an embodiment of the present invention;

[0043] Figure 4 This is an example diagram of pedestrian height and wind speed obtained from CFD simulation according to an embodiment of the present invention;

[0044] Figure 5 This is an example diagram of the surface temperature inversion result according to an embodiment of the present invention;

[0045] Figure 6 This is an example diagram of the multi-factor evaluation results of the suitability of ventilation corridor construction according to an embodiment of the present invention;

[0046] Figure 7 This is an example diagram of the circuit simulation results (cumulative current) of an embodiment of the present invention;

[0047] Figure 8 This is an example diagram of the circuit simulation results (current potential) of an embodiment of the present invention;

[0048] Figure 9 This is an example diagram of the circuit simulation results (normalized current) of an embodiment of the present invention;

[0049] Figure 10 This is an example diagram illustrating the extraction of potential wind source distribution in a ventilation corridor based on circuit simulation results, according to an embodiment of the present invention.

[0050] Figure 11 This is an example diagram illustrating the extraction of potential ventilation corridor range based on circuit simulation results according to an embodiment of the present invention.

[0051] Figure 12 This is a schematic diagram of a ventilation corridor system according to an embodiment of the present invention. Detailed Implementation

[0052] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0053] Combination Figure 1 The present invention provides a method for constructing urban ventilation corridors based on CFD and circuit theory, which includes data acquisition and preprocessing, urban wind field mapping, surface temperature inversion, suitability evaluation for wind corridor construction, circuit simulation, and ventilation corridor system construction.

[0054] The specific steps are as follows:

[0055] Data acquisition and preprocessing:

[0056] Acquire geographic information and meteorological data of the target area and perform preprocessing.

[0057] Specifically, in implementation, the data acquired includes digital elevation model data, remote sensing image data, building base maps and height vector data, road network vector data, green space and water system vector data, and multi-year wind direction and speed observation data. Preprocessing involves performing operations such as unified projection and cropping on the acquired geographic information data in the GIS platform, and removing missing values ​​and calculating the cumulative daily average wind speed and wind frequency in each direction on the acquired wind direction and speed data.

[0058] More specifically, preprocessing includes the following tasks:

[0059] Check the data:

[0060] Check and process outliers in the acquired digital elevation model data; check whether the remote sensing image data is a clear, cloudless recent summer daytime image of the target area; check and process geometric errors in the vector data of buildings, green spaces, water systems, and road networks; remove null values ​​and other outliers from the wind direction and wind speed data.

[0061] Unified coordinate system and scope:

[0062] In the GIS platform, projection and cropping operations are performed on the acquired digital elevation models, remote sensing images, building, green space, water system, and road network data to unify the projection coordinate system and range of the data.

[0063] Calculate the wind frequency and average wind speed in each direction:

[0064] As an optional implementation method, the annual average daily wind speed and wind frequency in each direction are calculated (excluding calm days, i.e., wind speed less than 0.1 m / s), and the specific calculation formulas are as shown in Formulas 1 and 2:

[0065]

[0066]

[0067] in The cumulative daily average wind speed is N, where N is the total number of days for wind speed and direction data, and V is the average daily wind speed over the years. i Let f be the average daily wind speed on day i. α Let n be the wind frequency in direction α. α This represents the number of days with direction α in the wind direction data. Depending on the data precision, you can choose to calculate the wind frequency in eight or sixteen directions.

[0068] Urban wind field mapping:

[0069] CFD simulation was used to obtain information about urban wind fields.

[0070] Specifically, a simplified 3D model of the city is established based on the building base map, height vector data, and digital elevation model data. The simplified 3D model of the city is then imported into CFD software to simulate the wind environment and obtain the steady-state wind field at a specific height.

[0071] In implementation, the undulating terrain and numerous buildings need to be simplified and represented by a limited number of patches. To reduce the number of modeling nodes while avoiding unreasonable patch division, a simplification method is proposed as an alternative implementation:

[0072] The special terrain and buildings in the target area are simplified separately.

[0073] like Figure 2 As shown, the mountains are simplified into a stepped, multi-layered right-angled frustum geometry based on contour lines. The contour line spacing is determined according to the height of the mountains in the study area; the higher the mountain, the larger the spacing. If there is a significant difference in the height of different mountains in the target area, different contour line spacings can be selected for mountains in different height ranges.

[0074] For buildings, a GIS platform is used to aggregate and generate new building patches with an 80m tolerance and roads and major waterways as obstacle surfaces, while unnecessary modeling nodes are removed. This process inevitably flattens the model, therefore the patch height needs to be stretched to a certain extent. As an optional implementation, the stretching formula is:

[0075] H = H e +H b (1)

[0076]

[0077] Where H is the height of each patch, H e H represents the average elevation of the patch. b Assign a height, h, to the patch building. i Let S be the height of the i-th building in the patch. iLet S be the base area of ​​the i-th building in patch i, and S be the total base area of ​​buildings in patch i. The building vector base map is converted into a 3D model in CAD. After adjustments based on the simplified mountain model and the simplified building model, the result is as follows: Figure 3 The target region shown is finally simplified in the model.

[0078] The steps for simulating the wind environment using CFD software are as follows:

[0079] Preprocessing includes importing the model, establishing the solution domain, and meshing. Importing the model involves importing the building and terrain models of the area to be simulated in a format recognizable by the CFD software. Establishing the solution domain determines the computational range for the CFD software to solve for fluid flow. Since the turbulence development caused by airflow passing over buildings and mountains requires space, the solution domain needs to be extended beyond the model's range. According to the guidelines of the Japan Academy of Building Research (AIJ) on building wind environment, this extension range is recommended as follows: inlet 3-5H, thickness 4H, width on both sides 3-5H, outlet 5-7H, where H is the highest height of the model. Mesh generation uses a discretized mesh to reflect the geometric characteristics of the model and serves as the unit for subsequent calculations and data storage. Overly fine mesh generation leads to low computational efficiency, while overly coarse mesh generation affects the reliability of the CFD simulation results.

[0080] The solution process includes establishing a turbulence model, setting boundary conditions, solving for steady-state flow, and determining convergence. Establishing a turbulence model involves selecting the model equations used in CFD software to solve for steady-state fluid flow. Setting boundary conditions involves determining wind speeds, pressures, and other conditions at the inlet, outlet, sides, top, and model walls of the solution domain to ensure the CFD simulation accurately reflects the climate characteristics of the target region. Solving for steady-state flow involves iteratively calculating the steady-state flow field in the solution domain under the aforementioned settings until the computational residuals decrease to an acceptable level, at which point the calculation results can be considered convergent.

[0081] Post-processing: This refers to the visualization and output of results, displaying simulation results in readable formats such as wind speed cloud maps and vector maps.

[0082] In this embodiment, scSTREAM software is used for simulation, and the specific process is as follows:

[0083] In the preprocessing step, the final simplified model of the target region in STL format is first imported, and then extended in the software to obtain the solution domain.

[0084] Considering the computational efficiency of the city-scale model, the extended range in this embodiment is set as follows: model entrance 3H, thickness 4H, both sides 3H, and exit 5H, where H is the highest height of the model.

[0085] To reduce computational cost while ensuring the reliability of the results, a structured mesh is created by limiting the minimum mesh size while inputting the ideal mesh number. The minimum mesh size is used to ensure that the geometric features of key regions of the model are well preserved. The scSTREAM software automatically stretches the mesh size of blank areas of the model with the ideal mesh number as the target.

[0086] In the solution process, the scSTREAM software only requires setting the basic boundary type to external flow field and inputting the wind direction and inlet wind speed to complete the boundary condition settings. For the turbulence model, this embodiment selects the RNG k-ε model from the Reynolds Average Navier-Stokes (RANS) equations to solve the steady-state problem of the incompressible fluid. The RANS equations perform Reynolds-averaged processing of the flow field physical quantities in the time domain, and then solve the resulting time-averaged governing equations. It boasts high computational efficiency and accuracy that generally meets the needs of routine research and industrial design, making it a widely used steady-state turbulence solution model.

[0087] The RNG k-ε model is an improved version of the standard k-ε model, offering advantages such as improved accuracy in fast strain flow and eddy current simulation, and performs well in simulating external wind environments of buildings. Other solution settings include: a calculation step size of 500, and convergence criteria where the turbulence dissipation rate, turbulence energy, and velocity residuals are all below 0.001.

[0088] like Figure 4 As shown, a wind speed cloud map should be generated at pedestrian height (approximately 1.5m) in the target area during post-processing. In this embodiment, the wind speed cloud map height is taken as 1.5m above the average elevation of the target area. Figure 4 In this context, Magnitude of Velocity refers to the speed.

[0089] Surface temperature inversion of the target area:

[0090] like Figure 5 As shown, this embodiment selects Landsat 8 remote sensing images of summer with less cloud cover in recent years to retrieve the surface temperature and obtain the surface temperature distribution of the target area.

[0091] A comprehensive multi-factor evaluation of the suitability of ventilation corridor construction in the target area was conducted.

[0092] Since buildings and terrain with high altitude, high undulation, and steep slope are the two most significant obstacles to wind flow in urban environments, this invention selects terrain conditions and the built environment as negative factors for the suitability of ventilation corridors. Open spaces are natural components of urban wind corridors, and roads are built spaces where urban wind corridors can be planned and constructed at low cost; therefore, the ventilation performance of open spaces and roads is selected as positive factors for the suitability of ventilation corridors.

[0093] These four elements basically cover the natural and anthropogenic factors influencing the suitability of ventilation corridor construction, enabling a relatively comprehensive evaluation while taking into account both the existing urban built environment and ventilation planning needs. Previously popular evaluation methods mainly involved calculating urban morphological parameters such as windward area index and sky openness, evaluating the suitability of ventilation corridor construction based on surface roughness.

[0094] This approach can relatively objectively quantify the degree to which urban features obstruct wind. However, as a highly practical and multifunctional planning tool, ventilation corridors often need to make full use of existing conditions and be aligned with the current state of urban construction and development intentions. Urban morphology methods focus too much on mechanical wind resistance indicators while neglecting other dimensions of urban characteristics. The evaluation method adopted in this invention strives to balance objectivity and comprehensiveness in the evaluation, so as to enhance the guiding ability of the evaluation results for ventilation corridor planning.

[0095] The specific indicators for each factor selection should be flexibly chosen based on the characteristics of the target region. The indicators selected in this embodiment are shown in Table 1:

[0096] Table 1. Factors and Indicators for the Suitability Evaluation of Ventilation Corridor Construction

[0097]

[0098] For each evaluation indicator, the target area's performance is scored on a five-level scale: high (9), relatively high (7), medium (5), relatively low (3), and low (1). The road direction (X) needs to be considered. 31 ), Road grade (X) 32 The weighted average yielded the single-factor evaluation results of road ventilation performance, with the patch direction (X) being considered. 42 ), patch width (X) 43 The weighted average yielded the evaluation results of the open space strip patches. In this embodiment, multiple experts were consulted, and the index weights were determined to be X based on the characteristics of the target area. 31 :X 32 =1.3:1, X 42 :X 42 =1:1.2.

[0099] The evaluation results of each single factor need to be superimposed according to a defined rule to obtain the multi-factor evaluation result. In this embodiment, the minimum value of the superimposed topographic condition and building environment evaluation results is taken to obtain the negative factor evaluation result, and the maximum value of the superimposed road ventilation performance and open space evaluation results is taken to obtain the positive factor evaluation result. The pairwise discriminant matrix method is used to superimpose the positive and negative factor evaluation results. The specific discriminant matrix is ​​shown in Table 2. The final multi-factor evaluation result of the suitability of ventilation corridor construction is as follows: Figure 6 As shown.

[0100] Table 2. Pairwise discrimination matrix of positive and negative elements

[0101]

[0102] Circuit simulation:

[0103] Circuit theory can be used to simulate wind flow in different urban spaces by drawing on the random walk of electrons in circuits. Like the minimum path method, it has the advantages of low data requirements and simple process. When encountering branching paths, the minimum path method only selects the one with the lowest cumulative cost, while in circuit theory, the current in a branch circuit is inversely proportional to its respective resistance. That is, when using circuit theory to simulate wind flow in cities, the wind at obstacle points will be distributed proportionally according to the ventilation potential (conductance) of different branch paths, much like current, which is more realistic than the result of the minimum path method simulating airflow concentrated on a single path. Circuit theory analysis can simultaneously solve for the connectivity benefits of individual paths and the global network. Just as adding branch circuits in a parallel circuit reduces the total resistance and increases the total current, adding wind flow paths under this algorithm will also improve the global ventilation capacity, which is highly consistent with the network connectivity sought in ventilation corridor construction. Furthermore, the circuit theory solution can provide the ventilation probability (cumulative current flow) of the entire study area, making it possible to identify the width of ventilation corridors and the bottlenecks in areas without potential wind corridors. Therefore, circuit theory is more suitable for simulating potential wind corridors than the minimum path method commonly used in existing wind corridor simulations.

[0104] The target area was simulated using the aforementioned CFD simulation, surface temperature inversion, and ventilation corridor construction suitability evaluation results. Specifically, the circuit theory calculation was performed using the Omniscape program developed based on the Julia language. The source surface was the CFD simulation results at a simplified location 1.5m above the average elevation of the urban model (i.e., at pedestrian height), and the wind speed was used as the power intensity. Considering the local circulation patterns and the purpose of ventilation corridors in mitigating the urban heat island, the target was only allowed to connect to sources with temperatures no higher than its own. The comprehensive evaluation results of ventilation corridor construction suitability were used as the electrical conductivity surface.

[0105] like Figures 7 to 9As shown, the circuit simulation results include three items: cumulative current, flow potential, and normalized current flow. The flow potential is the cumulative current output when the resistance of the entire study area is 1, characterizing the power source's ability to generate current. The cumulative current is the current result of the study area output by the Omniscape program, characterizing the current magnitude. The normalized current is the ratio of the cumulative current to the flow potential, used to evaluate the influence of the conductivity surface on the current after excluding the power source strength factor; a high value indicates that the current is significantly higher than expected, and the area is highly channelized due to significantly lower resistance than nearby pixels.

[0106] Construction of ventilation corridor system:

[0107] A ventilation corridor system for the target area is constructed based on the simulation results.

[0108] Specifically, this step first requires interpreting the cumulative current, normalized current, and current potential results obtained from the circuit simulation to determine the type and specific range of each element in the ventilation corridor system of the target area.

[0109] In this embodiment, the current potential characterizes the ability to generate wind and can be used to extract important wind sources in the ventilation corridor system. The cumulative current characterizes the ventilation conditions of the target area and can be used to identify the ventilation corridor network. The normalized current characterizes the impact of topography, buildings, roads, and open spaces on urban ventilation after excluding wind source intensity. High normalized current values ​​indicate that the nearby area has a high altitude or dense buildings, significantly reducing the number of paths available to airflow, or the existence of high-quality wind corridors with significantly better ventilation conditions than the surrounding area; low values ​​indicate that the current is significantly lower than expected, suggesting the existence of areas with obstructed ventilation. The normalized current can be used to extract high-quality wind corridor areas, severely obstructed ventilation areas, and key blockage points within wind corridors. Based on this, this embodiment establishes a conversion framework between the output results and the ventilation corridor construction strategy, as shown in Table 3:

[0110] Table 3. Circuit Theory - Ventilation Corridor Conversion Framework

[0111]

[0112] like Figures 10 to 11As shown: Based on the current potential value, the range of three levels of potential wind sources is extracted; based on the cumulative current value, the range of three types of potential wind corridors is extracted; and the normalized current value is divided into five categories: highly channelized area, slightly channelized area, general area, slightly obstructed wind corridor area, and severely obstructed wind corridor area. In this embodiment, the potential wind source range is defined as follows: core wind source area (current potential ≥ 2000), wind source buffer zone (1500 ≤ current potential < 2000), and wind source edge area (1200 ≤ current potential < 1500); the potential wind corridor is defined as follows: wind source area (cumulative current ≥ 1600), high wind volume corridor area (800 ≤ cumulative current < 1600), and medium wind volume corridor area (300 ≤ cumulative current < 800); the normalized current value classification boundary is as follows: highly channelized area (normalized current value > 1.3), slightly channelized area (normalized current value between 1.1 and 1.3), general area (normalized current value between 0.9 and 1.1), slightly obstructed wind corridor area (normalized current value between 0.7 and 0.9), and severely obstructed wind corridor area (normalized current value < 0.7).

[0113] Based on the characteristics of the target area and the results of circuit theory simulations, a three-element ventilation corridor system—"wind source—corridor—repair zone"—was determined. The wind source refers to the space capable of generating clean, cool air, including core and secondary wind sources; the corridor refers to the space transporting clean, cool air, including primary and secondary corridors; the repair zone refers to the area affecting the diffusion of clean air from the wind source or causing obstruction or even breakage of the corridor, requiring measures to reduce wind resistance and repair the wind corridor system. The final conclusion is as follows: Figure 12 The results of the urban ventilation corridor planning system for the target area are shown.

[0114] Compared to other technologies that directly use tools like CFD and WRF models to simulate ventilation corridors, which are too costly and difficult, and which rely solely on planning experience to directly interpret wind corridors or indirectly simulate them using minimum path algorithms due to their relatively coarse wind condition assessments and lack of aerodynamic fundamentals, this proposed solution balances the feasibility of the process with the reliability of the results, thus providing assistance to planning practice.

[0115] Combination Figures 1 to 12 A system for constructing urban ventilation corridors based on CFD and circuit theory, including:

[0116] The data preprocessing module is used to acquire and preprocess geographic information and meteorological data of the target area;

[0117] The urban wind field rendering module is used to obtain the background of urban wind speed distribution. It creates a simplified 3D model of the city and imports it into the software to simulate the wind environment and render the urban wind field.

[0118] The surface temperature inversion module is used to perform surface temperature inversion and obtain the surface temperature distribution of the target area.

[0119] A suitability evaluation module is constructed to conduct single-factor evaluations of the suitability of ventilation corridor construction in the target area, and the single-factor evaluation results are superimposed to obtain multi-factor comprehensive evaluation results.

[0120] The circuit simulation module is used to perform circuit simulations and then use the simulation results to construct a ventilation corridor system for the target area.

[0121] The ventilation corridor system construction module is used to construct an urban ventilation corridor system consisting of "wind source - corridor - repair area" based on circuit simulation results.

[0122] Current technologies for simulating potential ventilation corridors often employ the minimum path method, which is insensitive to low-level potential wind corridors, lacks width information, and has limited guidance for wind environment improvement strategies in areas lacking potential wind corridors. This solution, however, introduces circuit theory into the simulation of potential ventilation corridors, enabling better simulation of secondary wind corridors in the target area, intuitive display of corridor width, and identification of ventilation blockage points. The resulting urban ventilation corridor system is therefore more scientific and effective.

[0123] In addition, in related technologies, wind condition assessment often only uses a single prevailing wind direction or wind frequency charts in all directions. However, this solution uses CFD simulation results to assess the wind conditions in the target area, which can effectively obtain the range and relative intensity of the main wind sources in the target area, and help to determine ventilation corridors and formulate subsequent planning policies.

[0124] The invention and its embodiments have been described above illustratively. This description is not restrictive, and the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. The accompanying drawings are only one embodiment of the invention, and the actual structure is not limited thereto. No reference numerals in the claims should limit the scope of the claims. Therefore, if a person skilled in the art is inspired by this description and designs a similar structure and embodiment without departing from the spirit of the invention, such design should fall within the scope of protection of this patent. Furthermore, the word "comprising" does not exclude other elements or steps, and the word "a" preceding an element does not exclude the inclusion of "a plurality" of that element. Multiple elements stated in the product claims may also be implemented by a single element through software or hardware. The terms "first," "second," etc., are used to indicate names and do not indicate any specific order.

Claims

1. A method for constructing urban ventilation corridors based on CFD and circuit theory, comprising the following steps: Data Acquisition and Preprocessing: Acquire data for the target area, including digital elevation model data, remote sensing image data, building base maps and height vector data, road network vector data, green space and water system vector data, and multi-year wind direction and speed observation data; project and crop the acquired geographic information data in the GIS platform, remove missing values ​​from the acquired wind direction and speed data, calculate the cumulative daily average wind speed and wind frequency in each direction, and establish a simplified 3D urban model based on the building base maps, height vector data, and digital elevation model data; Urban wind field mapping: The simplified 3D model of the city is imported into CFD software for wind environment simulation to obtain the steady-state wind speed distribution at a specific height. The CFD software simulation of the wind environment includes preprocessing, solving, and post-processing: preprocessing includes importing the model, establishing the solution domain, and meshing; solving includes establishing a turbulence model, setting boundary conditions, solving for steady state, and determining convergence; post-processing includes displaying the simulation results using wind speed contour maps and vector maps. Land surface temperature inversion: Land surface temperature inversion is performed based on daytime remote sensing data to obtain the land surface temperature distribution in the target area; Suitableness evaluation for ventilation corridor construction: Single-factor evaluation of the suitability of ventilation corridor construction in the target area is conducted, and the results of the single-factor evaluation are superimposed to obtain a multi-factor comprehensive evaluation result; Circuit simulation: Combining the results of urban wind field and wind corridor construction suitability, circuit theory tools are used to simulate the wind environment current in the target area to obtain the cumulative current, current potential and normalized current. Construction of the ventilation corridor system: The cumulative current, current potential, and normalized current results obtained from circuit simulation are interpreted. The current potential characterizes the ability to generate wind and is used to extract important wind sources in the ventilation corridor system. The cumulative current characterizes the ventilation situation in the target area and is used to identify the ventilation corridor network. The normalized current characterizes the impact of topography, buildings, roads, and open spaces on urban ventilation after excluding wind source intensity factors, and is used to extract high-quality wind corridor areas, severely obstructed ventilation areas, and key blockage points within the wind corridors. Based on the current simulation results, a "wind source-corridor-repair area" urban ventilation corridor system is constructed.

2. The method for constructing urban ventilation corridors according to claim 1, characterized in that, The preprocessing steps are as follows: Check the data status; Unified coordinates and extent: Project and crop the acquired data in the GIS platform to unify the projection coordinate system and extent of the data; Calculate the wind frequency and average wind speed in each direction: ； ； The average daily wind speed over the years This represents the total number of days for wind speed and direction data. For the first The average daily wind speed of the day, For direction wind frequency, The direction in the wind direction data is The number of days.

3. The method for constructing urban ventilation corridors according to claim 2, characterized in that, The specific steps for checking the data are as follows: checking and processing outliers in the acquired digital elevation model data; checking remote sensing image data; checking and processing geometric errors in the vector data of buildings, green spaces, water systems, and road networks; Remove null values ​​and other outliers from the wind direction and wind speed data.

4. A system for constructing urban ventilation corridors based on CFD and circuit theory, used to execute the urban ventilation corridor construction method as described in any one of claims 1-3, characterized in that, The system includes a data acquisition and preprocessing module: acquiring data from the target area, including digital elevation model data, remote sensing image data, building base maps and height vector data, road network vector data, green space and water system vector data, and multi-year wind direction and speed observation data, and performing preprocessing; and an urban wind field mapping module: importing the acquired urban meteorological wind speed and a simplified urban 3D model into CFD software for wind field simulation to obtain the urban wind field conditions. Land surface temperature inversion module: Based on daytime remote sensing data, it performs land surface temperature inversion to obtain the land surface temperature distribution of the target area; The suitability evaluation module for the construction of ventilation corridors in the target area is used to conduct a single-factor evaluation of the suitability of the construction of ventilation corridors in the target area, and the single-factor evaluation results are superimposed to obtain a multi-factor comprehensive evaluation result. Circuit simulation module: Combining the results of urban wind field and wind corridor construction suitability, the module uses circuit theory tools to simulate wind environment current in the target area; Ventilation corridor system construction module: Based on the current simulation results, construct an urban ventilation corridor system consisting of "wind source - corridor - repair area".

Images