One-two-dimensional coupled urban hydrodynamic water quality whole-process high-efficiency high-resolution simulation method

Abstract

The invention discloses a one-dimensional and two-dimensional coupled urban hydrodynamic water quality whole-process high-efficiency and high-resolution simulation method, and provides a new treatment scheme for a detailed physical process aiming at the problem that an existing urban water environment pollution simulation method cannot efficiently, finely and integrally simulate an urban water environment pollution whole process. The surface runoff and pollutant transportation process is simulated on the basis of dynamic waves under a structure finite volume numerical discrete framework, so that the conservation of water quantity and water quality in the whole calculation process can be accurately ensured, and the surface of a research area is generalized into a grid calculation unit; and a dynamic link library is adopted to tightly couple a two-dimensional earth surface with a pipe network, a one-dimensional river channel and other hydrodynamic water quality transportation processes, various process mutual feedback and influence mechanisms in an urban water environment system can be disclosed, and the whole process of simulating the urban earth surface, an underground drainage system and a river and lake water environment in an efficient and high-precision integrated manner.

Description

Technical Field

[0001] The invention belongs to the technical field of urban water environment numerical simulation methods, and specifically relates to a one- and two-dimensional coupled urban hydrodynamic and water quality full-process high-efficiency and high-resolution simulation method. Background Art

[0002] The interactive transfer of water quantity and quality between the drainage system and urban roads and rivers is very complex, which brings great challenges to the simulation of the entire process of urban water environment. Therefore, it is of great significance to establish an efficient and high-precision numerical simulation method for urban water environment based on detailed physical processes, which can integrate the simulation of the entire process of urban surface, river and underground drainage system water environment, to explore the pollution mechanism of urban point sources and non-point sources, build sponge cities, treat black and odorous water bodies, and improve the quality and efficiency of sewage. It helps to fully understand the entire migration and transformation of pollutants in urban areas and the multi-process feedback mechanism. It can provide effective technical support for the precise tracing of urban water environment pollution and its treatment work and engineering measures such as sponge facility construction.

[0003] With the development of water environment simulation technology and the improvement of computing power, water environment numerical models have developed from single basin hydrological models, pipe network models and river channel models to multi-model coupling simulation. The integrated coupling simulation method of pipe network, river network and two-dimensional surface water environment has gradually become a research hotspot. The connection structure of the surface and underground drainage system is very complex, which will seriously affect the overall performance of the underground drainage system. At present, the coupling simulation method of surface water dynamics and underground drainage pipe network has made great progress and application, but the model of integrated surface water dynamics and its accompanying pollutants and underground drainage pipe network pollutant transport is still lacking. In the integrated water environment model simulation research, only the two-dimensional simulation of water area is basically considered, and no high-resolution simulation of water environment in urban water area and land area is considered at the same time. This is mainly because the urban land area contains key micro-topography such as roads and houses, and high-precision terrain data is required to meet the simulation accuracy requirements. At the same time, when simulating a large area of ​​urban area, millions of computational grids will be generated, which is also a major challenge to the stability and computational efficiency of the model.

[0004] Therefore, it is urgent to develop a high-resolution simulation method for the entire process of urban water environment with one- and two-dimensional dynamic bidirectional coupling for the integrated coupling simulation of the entire process of urban pipe network, river network and two-dimensional surface water environment. This provides effective technical support for the precise tracing of urban water environment pollution and its governance work, as well as engineering measures such as sponge facility construction. Summary of the invention

[0005] The purpose of the present invention is to provide a one- and two-dimensional coupled urban hydrodynamic and water quality full-process efficient and high-resolution simulation method to deepen the understanding of the full process of urban water environment mechanism and provide effective technical support for the precise prevention and control of water environment pollution.

[0006] In order to achieve the above-mentioned object, the technical scheme adopted by the present invention is: a high-efficiency and high-resolution simulation method for the whole process of urban hydrodynamics and water quality coupled with one or two dimensions, step 1, firstly discretizing the terrain data of the two-dimensional basin by using a structured grid, and then assigning the hydrological and hydrodynamic water quality parameter data of the structured grid, the one-dimensional pipe network and the river network according to the boundary conditions;

[0007] Step 2, the hydrological, hydrodynamic and water quality parameter data of the assigned structural grid is transmitted to the GPU, and the hydrological and hydrodynamic water quality transport process of the structural network is calculated in the GPU;

[0008] Step 3, respectively calculating the mass flux, momentum flux and source term on the structural grid interface during the hydrodynamic water mass transport process, and transmitting the result data to the CPU;

[0009] Step 4, according to the hydrological, hydrodynamic and water quality parameter data of the one-dimensional pipe network and the river network after the assignment, the hydrodynamic and water quality transfer process of the one-dimensional drainage pipe network and the river network is calculated in the CPU to obtain the hydrodynamic and water quality result data of the rainwater node and the river network section;

[0010] Step 5, performing water quantity and quality exchange calculation in the CPU on the one-dimensional drainage network rainwater node and river network section hydrodynamic and water quality result data obtained in step 4 and the structural grid hydrodynamic and water quality result data obtained in step 3;

[0011] Step 6, the water quantity and water quality exchange calculation results obtained in step 5 are transmitted to the GPU and the hydrological, hydrodynamic and water quality data of the structural grid are updated, and then the hydrodynamic and water quality data of the rainwater nodes and river network sections of the one-dimensional drainage network are updated in the CPU;

[0012] Step 7, based on the data obtained in step 6, the time step of the hydrological and hydrodynamic water quality transport process calculation is advanced by satisfying the stability conditions of the time step and the space step, and the model calculation of the next time step is performed;

[0013] Step 8: After the model calculation is completed, the GPU calculation results are transferred to the CPU and the results are output.

[0014] As a preferred technical solution of the present invention, in step 2, CUDA language is used for autonomous programming to implement GPU parallel computing.

[0015] As a preferred technical solution of the present invention, in step 2, the calculation of the two-dimensional grid hydrology and hydrodynamic water quality transfer process is specifically: using the finite volume method based on the Godunov format to spatially discretize the two-dimensional shallow water equation and the convection-diffusion equation; the calculation of the one-dimensional pipe network and river network hydrology and hydrodynamic water quality transfer process is specifically: using the dynamic wave method to calculate the one-dimensional pipe network and river network hydrodynamic water quality transfer process.

[0016] As a preferred technical solution of the present invention, in step 2, the coupling form of the two-dimensional shallow water equation and the convection-diffusion equation is expressed as follows:

[0017]

[0018] Where: t represents the time step, in seconds; x represents the horizontal coordinate, y represents the vertical coordinate; q represents the conserved variable, q x Indicates the single width flow in the x direction, in m 2 / s,q x =uh;q y Indicates the single width flow in the y direction, in m 2 / s,q y =vh; h is the water depth, in m; u is the average velocity in the x direction, in m / s; v is the average velocity in the y direction, in m / s; F is the flux vector in the x direction; G is the flux vector in the y direction; S is the source term vector; g is the gravitational acceleration, in m / s 2 ; z b Indicates the riverbed elevation in m; C f represents the bed surface roughness coefficient; i represents the net rainfall, in mm / h; C represents the vertical average concentration of pollutants, in mg / L; D x and D y are the diffusion coefficients in the x and y directions respectively; q in is the flow intensity of point source emission, m / s; C in is the vertical average concentration of the substance at the point source, mg / L.

[0019] As a preferred technical solution of the present invention, in the step 3, the mass and momentum flux calculations on the structural grid interface during the hydrodynamic water mass transfer process are calculated using the HLLC approximate Riemann solver; wherein: the source term part includes the bottom slope term and the friction term, the bottom slope source term processing adopts the method of decomposing the integral on the structural grid unit into the integral of the sub-unit, and by assuming that the bed bottom height and water level in the structural grid change linearly, the bottom slope source term of the grid is converted into the flux of the structural grid boundary; the friction source term processing adopts the friction source term calculation method.

[0020] As a preferred technical solution of the present invention, in step 3:

[0021] The HLLC approximate Riemann solver is used to calculate the mass and momentum fluxes on the structured grid interface during the hydrodynamic water mass transport process: first, the interface variables are reconstructed with spatial second-order accuracy to form a Riemann problem, and the MUSCL state interpolation method is used to numerically reconstruct the variables on the left and right sides of the unit interface. At the same time, the Min-Mod limiter is used to limit the gradient to effectively suppress numerical oscillations.

[0022] The calculation formula of friction source term is as follows:

[0023]

[0024] Where: x represents the horizontal coordinate, y represents the vertical coordinate; q x Indicates the single width flow in the x direction, in m 2 / s,q x =uh;q y Indicates the single width flow in the y direction, in m 2 / s,q y =vh; h is the water depth in m; u is the average velocity in the x direction in m / s; v is the average velocity in the y direction in m / s; S fx represents the friction source term in the x direction; S fy represents the friction source term in the y direction; C f Represents the bed surface roughness coefficient.

[0025] As a preferred technical solution of the present invention, in step 5, the water quantity and quality exchange between the structural grid and the rainwater node is achieved through a vertical connection method.

[0026] As a preferred technical solution of the present invention, in step 5, the water quantity and quality exchange between the structure grid and the one-dimensional river channel is achieved through a forward connection method.

[0027] The beneficial effects of the present invention are as follows: the one- and two-dimensional coupled urban hydrodynamic and water quality full-process efficient and high-resolution simulation method of the present invention is aimed at the problem that the existing urban water environment pollution simulation method cannot efficiently and finely simulate the entire process of urban water environment pollution in an integrated manner, and proposes a new treatment solution based on detailed physical processes. The finite volume method is used in the structural grid to simulate the surface runoff and pollutant transport process, which can accurately ensure the conservation of water quantity and quality in the entire calculation process, generalize the surface of the study area into grid calculation units, and use a dynamic link library to tightly couple the two-dimensional surface with the hydrodynamic and water quality transport processes such as the pipeline network and the one-dimensional river channel, which can reveal the various process feedbacks and influence mechanisms in the urban water environment system, and efficiently and accurately integrate the simulation of the entire process of urban surface, underground drainage system and river and lake water environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of a vertical connection example in the present invention;

[0029] Figure 2 The discharge flow rate and pollutant concentration change process in the present invention;

[0030] Figure 3 The pollutant concentration and flow field diagram of the plain area under the steady state in the present invention;

[0031] Figure 4 and Figure 5 A diagram showing the total amount of water entering the system and the total amount of pollutant load, the total amount of water discharged from the system and the total amount of pollutant load stored in the system, and their changes over time;

[0032] Figure 6 It is a schematic diagram of a forward connection example in the present invention;

[0033] Figure 7 It is the water level map of the plain area in the present invention;

[0034] Figure 8 and Fig. 9 The flow rate and the load per minute at the end of the one-dimensional river channel and discharged into the two-dimensional plain area in the present invention vary with time;

[0035] Fig.10 It is a comparison diagram of water depths at various sections along the river channel in the present invention. DETAILED DESCRIPTION

[0036] The technical solution of the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0037] Example 1

[0038] like Figure 1 As shown, the one- and two-dimensional coupled urban hydrodynamic and water quality full-process high-efficiency and high-resolution simulation method of the present invention is specifically implemented according to the following steps:

[0039] Step 1: First, the terrain data of the two-dimensional basin is discretized using a structured grid, and then the hydrological, hydrodynamic and water quality parameter data of the structured grid, the primary vascular network and the river network are assigned values ​​according to the boundary conditions;

[0040] Step 2, the hydrological, hydrodynamic and water quality parameter data of the assigned structural grid is transmitted to the GPU, and the hydrological and hydrodynamic water quality transport process of the structural network is calculated in the GPU;

[0041] Step 3, respectively calculating the mass flux, momentum flux and source term on the structural grid interface during the hydrodynamic water mass transport process, and transmitting the result data to the CPU;

[0042] Step 4, according to the hydrological, hydrodynamic and water quality parameter data of the one-dimensional pipe network and the river network after the assignment, the hydrodynamic and water quality transfer process of the one-dimensional drainage pipe network and the river network is calculated in the CPU to obtain the hydrodynamic and water quality result data of the rainwater node and the river network section;

[0043] Step 5, performing water quantity and quality exchange calculation in the CPU on the one-dimensional drainage network rainwater node and river network section hydrodynamic and water quality result data obtained in step 4 and the structural grid hydrodynamic and water quality result data obtained in step 3;

[0044] The water quantity and quality exchange between the structural grid and the rainwater node is achieved through the vertical connection method. Specifically:

[0045] Vertical connection is as follows Figure 1 The theoretical case shown is verified. The pipe network system consists of 6 nodes and 6 pipes. The two-dimensional surface is a square closed plain area with a side length of 200m, including nodes 2, 3, 4 and 5, and these nodes allow overflow and backflow. The water quantity and quality of the pipeline can be exchanged with the water quantity and quality of the surface through these four nodes. The attribute information of the pipes and nodes is shown in Table 1. The plain elevation is set to 0m and the roughness is set to 0.025. The connection method between the pipe and the node is flat connection at the bottom of the pipe. The water flow enters the system through node 1, and the inflow gradually increases from 0 to 1.0m within 10 minutes after the simulation starts. 3 / s, and then remain unchanged, the pollutant concentration is set to a constant value of 1mg / L; the water flows in the system and finally leaves the system through node 6, and the outlet is set to the free outflow boundary. The system is initially dry, that is, the initial water depth of the pipe and the plain is 0m.

[0046] Table 1 Attribute information of pipelines and nodes

[0047]

[0048] Figure 2 This is the flow process at the outlet of the pipe network. It can be seen from the figure that the pollutant concentration is 0 at the initial moment and then remains at 1 mg / L, which is consistent with the inflowing pollutant concentration.

[0049] Figure 3 The pollutant concentration and flow field diagram of the plain area under a stable state. The characteristics of overflow and backflow are characterized by the direction of the water flow arrows near the nodes. The divergence from the node indicates overflow, and the gathering from the surroundings to the node indicates backflow. The length of the arrow indicates the flow rate. The overflow and backflow of water and pollutants can be clearly seen in the figure. The pollutant concentration in the plain area is always maintained at 1 mg / L, which is consistent with the pollutant concentration flowing into the system from node 1.

[0050] From the perspective of water quantity and quality balance, the amount of water and pollutant load entering the system at node 1 should be equal to the sum of the outflow, surface water and pipe network storage. The cumulative overflow water and pollutant load at node 2 should be equal to the sum of the node return flow and surface water. Figure 4 and Figure 5The cumulative water volume and pollutant load entering and leaving the system change over time. It can be seen that the total water volume and pollutant load entering the system are consistent with the sum of the water volume and pollutant load discharged from the surface, pipeline storage and outlet.

[0051] In general, the simulation method proposed in the present invention can dynamically couple and simulate the water quantity and quality exchange process between the one-dimensional drainage system and the two-dimensional surface with high accuracy.

[0052] The water quantity and quality exchange between the structured grid and the one-dimensional river is achieved through the forward connection method. Specifically:

[0053] Figure 6 This is a schematic diagram of the forward connection example. The plain area is a square with closed boundaries on all sides, a side length of 200m, a river length of 360m and a width of 4m. The river model is calculated using SWMM and is divided into 10 river sections and 9 river sections. The downstream of the river is connected to the plain. The roughness of the river and the plain are 0.02 and 0.05 respectively, the elevation is 0m, the initial water level is set to 0.5m, the initial flow rate is set to 0m / s, and the initial pollutant concentration is set to 0mg / L. The water flows into the system from the upstream of the river (node ​​S1), and the inflow gradually increases from 0 to 4m within 10min of the start of the simulation. 3 / s, and finally remain unchanged, the pollutant concentration is set to a constant value of 1m / s. The simulation calculation time is 30min, and the output time interval is 30s.

[0054] The results obtained by simulation calculation of the full two-dimensional model and the literature model are used as standards, and compared with the calculation results of the coupling model simulation method to verify the accuracy and reliability of the simulation method of the present invention. Figure 7 This is the water level distribution diagram of the plain area at 1800s. It can be seen that the water level changes greatly at the coupling point of the one-dimensional and two-dimensional models. When the water flow in the one-dimensional river enters the relatively open plain area, the water flow diffuses, causing the water level on both sides to drop sharply.

[0055] Figure 8 and Fig. 9 This is a comparison of the flow rate and the load per minute at the end of the one-dimensional river channel and the discharge into the two-dimensional plain area over time. It can be seen that the flow process at the downstream end of the one-dimensional river channel and the pollutant load per minute are basically consistent.

[0056] Fig.10 The comparison is shown for the water depth at time t=0min and at each section along the river simulated by each model (t=30min). It can be seen that the simulation results of the model of the present invention are similar to those of the model in the literature and the full two-dimensional simulation results, indicating that the model of the present invention has good accuracy and reliability.

[0057] Step 6, the water quantity and water quality exchange calculation results obtained in step 5 are transmitted to the GPU and the hydrological, hydrodynamic and water quality data of the structural grid are updated, and then the hydrodynamic and water quality data of the rainwater nodes and river network sections of the one-dimensional drainage network are updated in the CPU;

[0058] Step 7, based on the data obtained in step 6, the time step of the hydrological and hydrodynamic water quality transport process calculation is advanced by satisfying the stability conditions of the time step and the space step, and the model calculation of the next time step is performed;

[0059] Step 8: After the model calculation is completed, the GPU calculation results are transferred to the CPU and the results are output.

[0060] Example 2

[0061] like Figure 1 As shown, different from Example 1, in step 2 of a one- and two-dimensional coupled urban hydrodynamic and water quality full-process efficient and high-resolution simulation method of the present invention, the two-dimensional grid hydrological and hydrodynamic water quality transfer process is calculated specifically by: using a finite volume method based on the Godunov format to spatially discretize the two-dimensional shallow water equation and the convection-diffusion equation; the one-dimensional pipe network and river network hydrological and hydrodynamic water quality transfer process is calculated specifically by: using a dynamic wave method to calculate the one-dimensional pipe network and river network hydrodynamic water quality transfer process.

[0062] The coupled form of the two-dimensional shallow water equation and the convection-diffusion equation is expressed as follows:

[0063]

[0064] Where: t represents the time step, the unit is s; x represents the horizontal coordinate, y represents the vertical coordinate; q represents the conserved variable, q x Indicates the single width flow in the x direction, in m 2 / s,q x =uh;q y Indicates the single width flow in the y direction, in m 2 / s,q y =vh; h is the water depth, in m; u is the average velocity in the x direction, in m / s; v is the average velocity in the y direction, in m / s; F is the flux vector in the x direction; G is the flux vector in the y direction; S is the source term vector; g is the gravitational acceleration, in m / s 2 ;z b Indicates the riverbed elevation in m; C f represents the bed surface roughness coefficient; i represents the net rainfall, in mm / h; C represents the vertical average concentration of pollutants, in mg / L; D x and D y are the diffusion coefficients in the x and y directions respectively; q inis the flow intensity of point source emission, m / s; C in is the vertical average concentration of the substance at the point source, mg / L.

[0065] Example 3

[0066] Different from Example 2, in step 3 of a one- and two-dimensional coupled urban hydrodynamic and water quality full-process efficient and high-resolution simulation method of the present invention, the mass and momentum flux calculations on the structural grid interface during the hydrodynamic and water quality transfer process are calculated using the HLLC approximate Riemann solver; wherein: the source term part includes a bottom slope term and a friction term, and the bottom slope source term processing is performed by decomposing the integral on the structural grid unit into an integral of sub-units, and by assuming that the bed height and water level within the structural grid change linearly, the bottom slope source term of the grid is converted into a flux at the boundary of the structural grid; the friction source term processing is performed using a friction source term calculation method.

[0067] The HLLC approximate Riemann solver is used to calculate the mass and momentum fluxes on the structured grid interface during the hydrodynamic water mass transport process: first, the interface variables are reconstructed with spatial second-order accuracy to form a Riemann problem, and the MUSCL state interpolation method is used to numerically reconstruct the variables on the left and right sides of the unit interface. At the same time, the Min-Mod limiter is used to limit the gradient to effectively suppress numerical oscillations.

[0068] The calculation formula of friction source term is as follows:

[0069]

[0070] Where: x represents the horizontal coordinate, y represents the vertical coordinate; q x Indicates the single width flow in the x direction, in m 2 / s,q x =uh;q y Indicates the single width flow in the y direction, in m 2 / s,q y =vh; h is the water depth in m; u is the average velocity in the x direction in m / s; v is the average velocity in the y direction in m / s; S fx represents the friction source term in the x direction; S fy represents the friction source term in the y direction; C f Represents the bed surface roughness coefficient.

[0071] Example 4

[0072] Different from Example 3, in step 5 of the one- and two-dimensional coupled urban hydrodynamic and water quality full-process high-efficiency and high-resolution simulation method of the present invention, the water quantity and water quality exchange between the structural grid and the rainwater node is achieved by a vertical connection method, specifically:

[0073] When the water level Z in the rainwater node is obtained j Below ground elevation Z g When the surface backflow is formed, that is, the surface rainwater and pollutants flow into the rainwater well, the weir flow formula is used to calculate the amount of water flowing back from the surface to the rainwater node:

[0074]

[0075] Where: Q wj is the water flow from the surface backflow to the rainwater node; C1 is the weir flow coefficient; w is the equivalent weir width of the overflow node; h1 is the difference between the ground water level and the surface elevation, that is, h1 = Z w -Z j ;

[0076] Since the amount of water entering the rainwater node is the water loss of the corresponding structure grid, the pollutant concentration entering the rainwater node is the pollutant concentration C of the corresponding structure grid. w ; Therefore, the pollutant load M1 entering the rainwater node at the current time step dt can be calculated using the following formula:

[0077] M1=Q wj C w dt (7)

[0078] In this case, there is no rainwater node overflow, so the water volume and pollutant concentration of the rainwater node overflow are both 0;

[0079] When the water level Z in the rainwater node is obtained j Below ground water level Z w But above ground level Z g When , surface backflow is formed, that is, surface rainwater flows into the rainwater node. At this time, the hole flow formula is used to calculate the amount of water flowing back from the surface to the rainwater node:

[0080]

[0081] Where: Q wj is the amount of water flowing back from the surface to the rainwater node; C2 is the orifice coefficient, which is 0.8 for rounded orifices and 0.6 for square orifices; A mh is the water inlet orifice area of ​​the rainwater node; the calculation method of the pollutant concentration and load entering the rainwater node from the surface is consistent with the calculation method of (a); h2 is the difference between the ground water level and the node water level, that is, h2 = Z w -Z j ;

[0082] When the water level Z in the rainwater node is obtained j Above ground water level Z w When , a node overflow is formed, that is, the water in the rainwater well overflows to the surface. At this time, the water flow rate of the node overflowing to the surface is calculated by the following formula:

[0083]

[0084] Where: Q jw is the water flow rate overflowing from the rainwater node to the surface; h3 is the difference between the water level at the rainwater node and the ground water level, that is, h2 = Z j -Z w ;

[0085] At this time, the pollutant concentration flowing from the rainwater node to the surface is the pollutant concentration C in the node. j , so the pollutant load M2 overflowing from the rainwater node to the surface at the current time step dt can be calculated by the following formula:

[0086] M2=Q jw C j dt (10)

[0087] At this time, the pollutant concentration of the structure grid i corresponding to the rainwater node at the previous moment is C i , the grid pollutant load M3 can be expressed by the following formula:

[0088] M3=C i V i (11)

[0089] Where: V i is the surface water volume corresponding to the structure grid i at the previous moment. After dt time, the pollution overflowed from the overflow node mixes with the surface water. At this time, it is considered that the grid concentration is vertically averaged and the mixing time is short, so the pollutant concentration C of the structure grid i after dt time is in The following method can be used to update.

[0090]

[0091] Example 5

[0092] like Figure 1 As shown, different from Example 4, in step 5 of the one-dimensional coupled urban hydrodynamic and water quality full-process high-efficiency and high-resolution simulation method of the present invention, in step 5, the water quantity and water quality exchange between the structure grid and the one-dimensional river channel is achieved by a forward connection method, specifically:

[0093] The forward connection water quantity and quality exchange is calculated by establishing a connection between the two ends of the one-dimensional river channel and the structural grid river channel, using the one-dimensional river channel and the structural grid river channel to provide boundary conditions for each other;

[0094] The structured grid river uses the downstream flow of the one-dimensional river as the flow boundary condition, that is:

[0095]

[0096] Where: is the flow rate of the section connecting the one-dimensional river channel and the structural grid, m 3 / s; M is the number of grid unit edges connecting the structural grid channel and the one-dimensional channel; l k is the length of the grid unit side, m; q k is the single width flow rate at the edge of the grid unit, m 3 / s; the pollutant concentration at the connection section between the two-dimensional structure grid river channel and the one-dimensional river channel is consistent with the pollutant concentration at the downstream section of the one-dimensional river channel;

[0097] The one-dimensional river network model uses the structural grid water level at the coupling section of the two-dimensional structural grid river channel as the lower boundary condition; the weighted average water level of the structural grid at the connection point is used as the fixed water level boundary condition of the one-dimensional river channel at the connection section with the structural grid.

[0098]

[0099] Where: is the water level of the one-dimensional river channel at the next time step, m; is the water level value of the structural grid, m; L is the total length of the positive connection boundary, m;

[0100] The weighted average pollution load of the connection unit is used as the fixed pollution load boundary condition of the one-dimensional river channel;

[0101]

[0102] Where: is the pollutant concentration boundary condition for the next time step in the river channel, mg / L; is the grid pollutant concentration value, mg / L; is the grid water depth value, m; H is the sum of the water depths of the positively connected boundary grids.

[0103] Example 6

[0104] Different from Example 5, in step 2 of the one- and two-dimensional coupled urban hydrodynamics and water quality full-process efficient and high-resolution simulation method of the present invention, CUDA language is used for independent programming to implement GPU parallel computing.

[0105] The above description shows and describes several preferred embodiments of the invention, but as mentioned above, it should be understood that the invention is not limited to the form disclosed in the present invention, and should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the inventive concept described in the present invention through the above teachings or the technology or knowledge of the relevant field. The changes and modifications made by those skilled in the art shall be within the scope of protection of the claims attached to the invention without departing from the spirit and scope of the invention.

Claims

1. A one- and two-dimensional coupled high-efficiency and high-resolution simulation method for the entire process of urban hydrodynamics and water quality, characterized by: Follow the steps below to implement it: Step 1: First, the terrain data of the two-dimensional basin is discretized using a structured grid, and then the hydrological, hydrodynamic and water quality parameter data of the structured grid, the primary vascular network and the river network are assigned values ​​according to the boundary conditions; Step 2, the hydrological, hydrodynamic and water quality parameter data of the assigned structural grid is transmitted to the GPU, and the hydrological and hydrodynamic water quality transport process of the structural network is calculated in the GPU; Step 3, respectively calculating the mass flux, momentum flux and source term on the structural grid interface during the hydrodynamic water mass transport process, and transmitting the result data to the CPU; Step 4, according to the hydrological, hydrodynamic and water quality parameter data of the one-dimensional pipe network and the river network after the assignment, the hydrodynamic and water quality transfer process of the one-dimensional drainage pipe network and the river network is calculated in the CPU to obtain the hydrodynamic and water quality result data of the rainwater node and the river network section; Step 5, performing water quantity and quality exchange calculation in the CPU on the one-dimensional drainage network rainwater node and river network section hydrodynamic and water quality result data obtained in step 4 and the structural grid hydrodynamic and water quality result data obtained in step 3; Step 6, the water quantity and water quality exchange calculation results obtained in step 5 are transmitted to the GPU and the hydrological, hydrodynamic and water quality data of the structural grid are updated, and then the hydrodynamic and water quality data of the rainwater nodes and river network sections of the one-dimensional drainage network are updated in the CPU; Step 7, based on the data obtained in step 6, the time step of the hydrological and hydrodynamic water quality transport process calculation is advanced by satisfying the stability conditions of the time step and the space step, and the model calculation of the next time step is performed; Step 8: After the model calculation is completed, the GPU calculation results are transferred to the CPU and the results are output.

2. The one- and two-dimensional coupled urban hydrodynamic and water quality full-process high-efficiency and high-resolution simulation method according to claim 1 is characterized in that: In step 2, CUDA language is used for independent programming to implement GPU parallel computing.

3. The one- and two-dimensional coupled urban hydrodynamic and water quality full-process high-efficiency and high-resolution simulation method according to claim 2 is characterized in that: In step 2, the two-dimensional grid hydrology and hydrodynamic water quality transfer process is calculated specifically by using a finite volume method based on the Godunov format to spatially discretize the two-dimensional shallow water equation and the convection-diffusion equation; the one-dimensional pipe network and river network hydrology and hydrodynamic water quality transfer process is calculated specifically by using a dynamic wave method to calculate the one-dimensional pipe network and river network hydrodynamic water quality transfer process.

4. The one- and two-dimensional coupled urban hydrodynamic and water quality full-process high-efficiency and high-resolution simulation method according to claim 3 is characterized in that: In step 2, the two-dimensional shallow water equation and the convection-diffusion equation are coupled as follows: Where: t represents the time step, the unit is s; x represents the horizontal coordinate, y represents the vertical coordinate; q represents the conserved variable, q x Indicates the single width flow in the x direction, in m 2 / s,q x =uh;q y Indicates the single width flow in the y direction, in m 2 / s,q y =vh; h is the water depth, in m; u is the average velocity in the x direction, in m / s; v is the average velocity in the y direction, in m / s; F is the flux vector in the x direction; G is the flux vector in the y direction; S is the source term vector; g is the gravitational acceleration, in m / s 2 ;z b Indicates the riverbed elevation in m; C f represents the bed surface roughness coefficient; i represents the net rainfall, in mm / h; C represents the vertical average concentration of pollutants, in mg / L; D x and D y are the diffusion coefficients in the x and y directions respectively; q in is the flow intensity of point source emission, m / s; C in is the vertical average concentration of the substance at the point source, mg / L.

5. The one- and two-dimensional coupled urban hydrodynamic and water quality full-process high-efficiency and high-resolution simulation method according to claim 4 is characterized in that: In the step 3, the mass and momentum fluxes on the interface of the structural grid during the hydrodynamic water mass transfer process are calculated using the HLLC approximate Riemann solver; wherein: the source term part includes the bottom slope term and the friction term, the bottom slope source term is processed by decomposing the integral on the structural grid unit into the integral of the sub-unit, and by assuming that the bed height and water level in the structural grid change linearly, the bottom slope source term of the grid is converted into the flux of the structural grid boundary; the friction source term is processed by the friction source term calculation method.

6. The one- and two-dimensional coupled urban hydrodynamic and water quality full-process high-efficiency and high-resolution simulation method according to claim 5 is characterized in that: In step 3: The HLLC approximate Riemann solver is used to calculate the mass and momentum fluxes on the structured grid interface during the hydrodynamic water mass transport process: first, the interface variables are reconstructed with spatial second-order accuracy to form a Riemann problem, and the MUSCL state interpolation method is used to numerically reconstruct the variables on the left and right sides of the unit interface. At the same time, the Min-Mod limiter is used to limit the gradient to effectively suppress numerical oscillations. The calculation formula of friction source term is as follows: Where: x represents the horizontal coordinate, y represents the vertical coordinate; q x Indicates the single width flow in the x direction, in m 2 / s,q x =uh;q y Indicates the single width flow in the y direction, in m 2 / s,q y =vh; h is the water depth in m; u is the average velocity in the x direction in m / s; v is the average velocity in the y direction in m / s; S fx represents the friction source term in the x direction; S fy represents the friction source term in the y direction; C f Represents the bed surface roughness coefficient.

7. The one- and two-dimensional coupled urban hydrodynamic and water quality full-process high-efficiency and high-resolution simulation method according to claim 6 is characterized in that: In step 5, the water quantity and quality exchange between the structural grid and the rainwater node is achieved through a vertical connection method.

8. The one- and two-dimensional coupled urban hydrodynamic and water quality full-process high-efficiency and high-resolution simulation method according to claim 7 is characterized in that: In step 5, the water quantity and quality exchange between the structure grid and the one-dimensional river channel is achieved through the forward connection method.

Images