CN110188484B - Hydrodynamic water quality model self-adaptive grid generation method - Google Patents

Hydrodynamic water quality model self-adaptive grid generation method Download PDF

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CN110188484B
CN110188484B CN201910474850.8A CN201910474850A CN110188484B CN 110188484 B CN110188484 B CN 110188484B CN 201910474850 A CN201910474850 A CN 201910474850A CN 110188484 B CN110188484 B CN 110188484B
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CN110188484A (en
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冶运涛
曹引
蒋云钟
毕忠飞
梁犁丽
顾晶晶
赵红莉
尚毅梓
龚家国
张双虎
仇亚琴
贾玲
郝春沣
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China Institute of Water Resources and Hydropower Research
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Abstract

The invention discloses a hydrodynamic water quality model self-adaptive grid generation method, which comprises the following steps: s1, generating a plurality of leaf grids and a plurality of sub-grids covering the calculation domain; s2, acquiring the terrain gradient of the sub-grid; s3, selecting leaf grids according to the terrain gradient of the sub-grids and the relative position relation between the boundary seed points of the target area and the centers of the sub-grids, and adjusting the division level of the selected leaf grids to be the lowest division level; s4, acquiring the water level gradient and the pollutant concentration gradient of the sub-grid of the leaf grid which is not at the maximum division level; and S5, adjusting the division level of the corresponding leaf grid again according to the water level gradient, the pollutant concentration gradient and the dry and wet boundary to obtain a plurality of sub-grids after being divided again. The method can refine the grids in the area with larger terrain gradient, can self-adaptively adjust the size of the grids according to the water level and the pollutant concentration gradient, and can ensure the still water harmony of the model and the simulation precision of the model in the calculation process.

Description

Hydrodynamic water quality model self-adaptive grid generation method
Technical Field
The invention relates to the field of water quality model self-adaptive grids, in particular to a hydrodynamic water quality model self-adaptive grid generation method.
Background
The hydrodynamic water quality model is an important tool for water environment management, and can acquire the continuous water quality condition in time and space. The accurate discrete solving of the control equation is the key for solving the two-dimensional hydrodynamic model, the grid is a discrete basic unit of the control equation, the type and the size of the grid can influence the simulation precision, the stability and the calculation efficiency of the hydrodynamic water quality model, and the method is always the key point for researching the hydrodynamic water quality model. According to different division modes, the model mesh mainly comprises a structural mesh, an orthogonal fit mesh and a non-structural mesh. The adaptation capability of the body-attached grid and the non-structural grid to the complex terrain and the boundary is strong, but the pretreatment process is complex, the grid is difficult to generate, and compared with the structure grid, the structure grid is easier to generate, but the adaptation to the irregular complex terrain boundary is poor. In order to improve the model simulation accuracy, the number of grids must be increased, which inevitably reduces the model calculation efficiency.
In order to improve the computational efficiency of the model, in recent years, an adaptive grid technology becomes an important direction for hydrodynamic model research, and the adaptive grid technology can adaptively adjust the size of a grid according to the water level gradient, the pollutant concentration gradient and other criteria, refine a leaf grid to generate a plurality of sub-grids, or merge the sub-grids. In the process of generating the sub-grids by refining the leaf grids through the self-adaptive grid technology, in order to improve the fitting capability of the sub-grids to the terrain, the central elevation of the sub-grids generated by refining the leaf grids is usually obtained by adopting an interpolation method, so that the central elevation of the sub-grids and the central elevation of the leaf grids are possibly inconsistent, in order to ensure the quality conservation in the sub-grid generation process, the water level of the sub-grids needs to be adjusted, the water level of the sub-grids, the water level of the leaf grids and the water level of the neighbor grids are inconsistent under the still water condition, further false water flow is generated, and the still water harmony of the model is damaged.
Disclosure of Invention
Aiming at the defects in the prior art, the method for generating the hydrodynamic water quality model adaptive grid solves the problems that the conventional adaptive grid generation method is easy to generate false water flow and destroy the still water harmony of the model.
In order to achieve the purpose of the invention, the invention adopts the technical scheme that:
the method for generating the self-adaptive grid of the hydrodynamic water quality model comprises the following steps:
s1, generating a plurality of leaf grids covering the calculation domain, and dividing the leaf grids into a plurality of sub-grids according to the initial division level of the leaf grids; wherein the initial partition level is a maximum partition level; wherein the leaf grid is a maximum grid cell;
s2, acquiring the terrain gradient of the sub-grid; acquiring the relative position relation between the boundary seed points of the target area and the center of the sub-grid;
s3, selecting leaf grids according to the terrain gradient of the sub-grids and the relative position relation between the boundary seed points of the target area and the centers of the sub-grids, and adjusting the division level of the selected leaf grids to be the lowest division level;
s4, acquiring the water level gradient and the pollutant concentration gradient of the sub-grid of the leaf grid which is not at the maximum division level;
s5, adjusting the division level of the corresponding leaf grid again according to the water level gradient, the pollutant concentration gradient and the dry and wet boundary to obtain a plurality of sub-grids after re-division;
s6, judging whether the size of the sub grid of each leaf grid is 2 times, 1 time or 1/2 times of the size of the sub grid of the adjacent leaf grid, and if so, entering the step S7; otherwise, go to step S8;
s7, judging whether to continue generating grids, if so, returning to the step S4, and if not, finishing generating grids;
and S8, increasing the division level of the adjacent leaf grids which do not meet the multiple relation by one level, then subdividing the sub grids, and returning to the step S6.
Further, the specific method for acquiring the terrain gradient of the sub-grid in step S2 is as follows:
according to the formula
Figure GDA0002543026280000031
Figure GDA0002543026280000032
Figure GDA0002543026280000033
Obtaining a terrain slope gradz of the sub-grid (i, j, is, is)b(i, j, is, is); wherein z isb(i, j, is, js) is the center elevation of the subgrid (i, j, is, is); z is a radical ofb-east、zb-west、zb-northAnd zb-southThe central elevations of the neighbor grids of the sub-grids (i, j, is, is) in the east, west, north and south directions respectively; Δ x is the length of the subgrid (i, j, is, is) in the x-axis direction, and Δ x is Δ x0/Ms，Δx0The length of a leaf grid (i, j) of the ith row and the jth column of the sub grid (i, j, is, is) in the x-axis direction, and Ms is the maximum division level of the leaf grid (i, j) in the x-axis direction; Δ y is the length of the subgrid (i, j, is, is) in the y-axis direction, and Δ y is Δ y0/Ns，Δy0The length of a leaf grid (i, j) where the sub grid (i, j, is, is) is located in the y-axis direction, and Ns is the maximum division level of the leaf grid (i, j) in the y-axis direction;
Figure GDA0002543026280000034
and
Figure GDA0002543026280000035
is an intermediate parameter.
Further, the specific method of step S3 includes the following sub-steps:
s3-1, a will number a1Setting the mark of the sub-grid adjacent to the boundary seed point of the target area; will number a2Setting the marks of the rest sub grids;
s3-2, marking the existence sub-grid as a1Maintaining the division level of the leaf mesh as the maximum division level, and modifying the signs of all the sub-meshes in the leaf mesh to a3；
S3-3, maintaining the division level of the leaf grids with the terrain slopes of all the sub grids larger than the elevation threshold value as the maximum division level, and marking all the sub gridsModified as3；
S3-4, marking the existence sub-grid as a2The leaf meshes are selected and the division level of the leaf meshes is adjusted to the lowest division level, and a plurality of new sub-meshes are generated.
Further, the specific method of step S4 includes the following sub-steps:
s4-1, judging whether the water depth of any sub grid is smaller than the preset minimum water depth, if so, taking the sub grid as a dry grid, setting the water level gradient and the pollutant concentration of the dry grid to be 0, and entering the step S4-7; otherwise, go to step S4-2;
s4-2, obtaining a grid center p of the sub grid, and obtaining neighbor leaf grids of the sub grid in four directions of east, west, north and south;
s4-3, judging whether the division level of the leaf grid where the sub grid is located is the same as that of the neighbor leaf grid, if so, taking the water level and the pollutant conservation concentration of the neighbor leaf grid as the water level and the pollutant conservation concentration of the sub grid in the direction, and entering the step S4-7; otherwise, entering step S4-4;
s4-4, judging whether the division level of the leaf grid where the sub grid is located is one level lower than that of the neighbor leaf grid, if so, taking the average value of the water levels and the pollutant conservation concentrations of all the sub grids in the neighbor leaf grid as the water level and the pollutant conservation concentration of the sub grid in the direction, and entering the step S4-7; otherwise, entering step S4-5;
s4-5, taking the adjacent leaf mesh of the sub mesh as a first mesh, and taking the leaf mesh which is adjacent to the first mesh and shares a vertex with the sub mesh as a second mesh; judging whether the division level of the leaf grid of the sub-grid is one level greater than that of the first grid or not, and whether the division level of the second grid is one level greater than that of the first grid or not, if so, respectively according to a formula
Figure GDA0002543026280000041
Figure GDA0002543026280000042
Acquiring the water level eta (in) and the pollutant conservation concentration qc (in) of the sub-grid in the direction, and entering step S4-7; otherwise, entering step S4-6; where η (p) represents the water level at the grid center p of the submesh; η (1) is the water level at the grid center of the first grid; η (2) is the water level in the second grid at the center of the sub-grid closest to the sub-grid; qc (p) is the contaminant conservation concentration at the grid center of the first grid; qc (1) is the contaminant-conservative concentration at the grid center of the first grid; qc (2) is the contaminant-conservative concentration at the center of the submesh closest to the submesh in the second grid;
s4-6, respectively according to the formula
Figure GDA0002543026280000051
Figure GDA0002543026280000052
Acquiring the water level eta (in) and the pollutant conservation concentration qc (in) of the sub-grid in the direction, and entering step S4-7; where η (p) is the water level at the grid center p of the sub-grid; η (1) is the water level at the grid center of the first grid; η (2) is the water level at the center of the submesh closest to the submesh in the second grid, i.e., the water level at the center of the second grid; qc (p) is the contaminant conservation concentration at the grid center of the first grid; qc (1) is the contaminant-conservative concentration at the grid center of the first grid; qc (2) is the contaminant conservative concentration at the center of the submesh closest to the submesh in the second grid, i.e., the contaminant conservative concentration at the center of the second grid;
s4-7, according to the formula
Figure GDA0002543026280000053
Figure GDA0002543026280000054
Figure GDA0002543026280000055
Figure GDA0002543026280000056
Obtaining water level gradient grad η (i, j, is, js) and pollutant concentration gradient gradqc (i, j, is, js) of the sub-grid of the leaf grid with the lowest division level, wherein η (i, j, is, js) is the elevation of the sub-grid (i, j, is, js), ηeast、ηwest、ηnorthAnd ηsouthThe water levels of the east, west, north and south directions of the sub-grids (i, j, is, js) are respectively; qc (i, j, is, js) is the contaminant concentration of the subgrid (i, j, is, js); qc is a product ofeast、qcwest、qcnorthAnd qcsouthThe pollutant conservation concentrations of the east, west, north and south directions of the sub-grids (i, j, is, js) are respectively.
Further, the specific method of step S5 includes the following sub-steps:
s5-1, according to the formula
gradΦ(i,j,is,js)＝max(gradη(i,j,is,js),gradqc(i,j,is,js))
Obtaining the value of a parameter grad phi (i, j, is, js); where max (·) is a maximum selection function;
s5-2, judging whether the sub-grid (i, j, is, js) is positioned at a dry-wet boundary, if so, entering the step S5-3; otherwise, entering step S5-4;
s5-3, judging whether the division level of the leaf grid of the sub grid is the maximum division level, if so, maintaining the maximum division level, otherwise, increasing the division level of the leaf grid of the sub grid by one level to obtain a plurality of sub grids after re-division, and entering the step S6;
s5-4, judging whether the grad phi (i, j, is, js) is larger than the threshold value, if so, entering the step S5-3; otherwise, entering step S5-5;
s5-5, reducing the division level of the leaf grid where the sub grid is located by one level to obtain a plurality of sub grids which are divided again, and entering the step S6.
The invention has the beneficial effects that: the method can refine the grids in the area with larger terrain gradient, can self-adaptively adjust the size of the grids according to the water level and the pollutant concentration gradient, and can ensure the still water harmony of the model and the simulation precision of the model in the calculation process.
Drawings
FIG. 1 is a schematic flow diagram of the present invention;
FIG. 2 is a diagram illustrating the relationship between a leaf grid and a sub-grid;
FIG. 3 is a diagram illustrating a scene of water levels and conservation concentrations of contaminants in an east direction for a sub-grid;
FIG. 4 is a schematic diagram of bottom elevation and initial water level parameters in an example;
FIG. 5 is a graph showing the simulation results of the flow rate under the present method;
FIG. 6 is a graph showing the results of a simulation of contaminant concentration under the present method;
FIG. 7 is a schematic diagram of the grid distribution at different times during the simulation process using the method of the present invention;
FIG. 8 is a graph showing the simulation results of the flow rate in the conventional method;
FIG. 9 is a graph showing the results of a simulation of contaminant concentration in a conventional process;
fig. 10 is a schematic diagram of the grid distribution at different time points in the simulation process using the conventional method.
Detailed Description
The following description of the embodiments of the present invention is provided to facilitate the understanding of the present invention by those skilled in the art, but it should be understood that the present invention is not limited to the scope of the embodiments, and it will be apparent to those skilled in the art that various changes may be made without departing from the spirit and scope of the invention as defined and defined in the appended claims, and all matters produced by the invention using the inventive concept are protected.
As shown in fig. 1 and 2, the method for generating the hydrodynamic water quality model adaptive mesh includes the following steps:
s1, generating a plurality of leaf grids covering the calculation domain, and dividing the leaf grids into a plurality of sub-grids according to the initial division level of the leaf grids; wherein the initial partition level is a maximum partition level; wherein the leaf grid is a maximum grid cell;
s2, acquiring the terrain gradient of the sub-grid; acquiring the relative position relation between the boundary seed points of the target area and the center of the sub-grid;
s3, selecting leaf grids according to the terrain gradient of the sub-grids and the relative position relation between the boundary seed points of the target area and the centers of the sub-grids, and adjusting the division level of the selected leaf grids to be the lowest division level;
s4, acquiring the water level gradient and the pollutant concentration gradient of the sub-grid of the leaf grid which is not at the maximum division level;
s5, adjusting the division level of the corresponding leaf grid again according to the water level gradient, the pollutant concentration gradient and the dry and wet boundary to obtain a plurality of sub-grids after re-division;
s6, judging whether the size of the sub grid of each leaf grid is 2 times, 1 time or 1/2 times of the size of the sub grid of the adjacent leaf grid, and if so, entering the step S7; otherwise, go to step S8;
s7, judging whether to continue generating grids, if so, returning to the step S4, and if not, finishing generating grids;
and S8, increasing the division level of the adjacent leaf grids which do not meet the multiple relation by one level, then subdividing the sub grids, and returning to the step S6.
The specific method for acquiring the terrain gradient of the sub-grid in step S2 is as follows: according to the formula
Figure GDA0002543026280000081
Figure GDA0002543026280000082
Figure GDA0002543026280000083
Obtaining the location of the sub-grid (i, j, is, is)Shape gradient gradzb(i, j, is, is); wherein z isb(i, j, is, js) is the center elevation of the subgrid (i, j, is, is); z is a radical ofb-east、zb-west、zb-northAnd zb-southThe central elevations of the neighbor grids of the sub-grids (i, j, is, is) in the east, west, north and south directions respectively; Δ x is the length of the subgrid (i, j, is, is) in the x-axis direction, and Δ x is Δ x0/Ms，Δx0The length of a leaf grid (i, j) of the ith row and the jth column of the sub grid (i, j, is, is) in the x-axis direction, and Ms is the maximum division level of the leaf grid (i, j) in the x-axis direction; Δ y is the length of the subgrid (i, j, is, is) in the y-axis direction, and Δ y is Δ y0/Ns，Δy0The length of a leaf grid (i, j) where the sub grid (i, j, is, is) is located in the y-axis direction, and Ns is the maximum division level of the leaf grid (i, j) in the y-axis direction;
Figure GDA0002543026280000084
and
Figure GDA0002543026280000085
is an intermediate parameter.
The specific method of step S3 includes the following substeps:
s3-1, a will number a1Setting the mark of the sub-grid adjacent to the boundary seed point of the target area; will number a2Setting the marks of the rest sub grids;
s3-2, marking the existence sub-grid as a1Maintaining the division level of the leaf mesh as the maximum division level, and modifying the signs of all the sub-meshes in the leaf mesh to a3；
S3-3, maintaining the division level of the leaf grids with the terrain slopes of all the sub grids larger than the elevation threshold value as the maximum division level, and modifying the marks of the sub grids as a3；
S3-4, marking the existence sub-grid as a2The leaf meshes are selected and the division level of the leaf meshes is adjusted to the lowest division level, and a plurality of new sub-meshes are generated.
The specific method of step S4 includes the following substeps:
s4-1, judging whether the water depth of any sub grid is smaller than the preset minimum water depth, if so, taking the sub grid as a dry grid, setting the water level gradient and the pollutant concentration of the dry grid to be 0, and entering the step S4-7; otherwise, go to step S4-2;
s4-2, obtaining a grid center p of the sub grid, and obtaining neighbor leaf grids of the sub grid in four directions of east, west, north and south;
s4-3, as shown in FIG. 3(a), judging whether the division level of the leaf grid where the sub grid is located is the same as that of the neighboring leaf grid, if so, taking the water level and the pollutant conservation concentration of the neighboring leaf grid as the water level and the pollutant conservation concentration of the sub grid in the direction, and entering the step S4-7; otherwise, entering step S4-4;
s4-4, as shown in FIG. 3(b), judging whether the division level of the leaf grid where the sub-grid is located is one level lower than that of the neighboring leaf grid, if so, taking the average value of the water levels and the pollutant conservation concentrations of all the sub-grids in the neighboring leaf grid as the water level and the pollutant conservation concentration of the sub-grid in the direction, and entering the step S4-7; otherwise, entering step S4-5;
s4-5, taking the adjacent leaf mesh of the sub mesh as a first mesh, and taking the leaf mesh which is adjacent to the first mesh and shares a vertex with the sub mesh as a second mesh; judging whether the division level of the leaf grid where the sub-grid is located is one level greater than the division level of the first grid or not and whether the division level of the second grid is one level greater than the division level of the first grid or not as shown in fig. 3(c), if so, respectively according to a formula
Figure GDA0002543026280000091
Figure GDA0002543026280000101
Acquiring the water level eta (in) and the pollutant conservation concentration qc (in) of the sub-grid in the direction, and entering step S4-7; otherwise, entering step S4-6; where η (p) represents the water level at the grid center p of the submesh; η (1) is the water level at the grid center of the first grid; η (2) is the water level in the second grid at the center of the sub-grid closest to the sub-grid; qc (p) is the contaminant conservation concentration at the grid center of the first grid; qc (1) is the contaminant-conservative concentration at the grid center of the first grid; qc (2) is the contaminant-conservative concentration at the center of the submesh closest to the submesh in the second grid;
s4-6, the fourth scenario is shown in FIG. 3(d), according to the formula
Figure GDA0002543026280000102
Figure GDA0002543026280000103
Acquiring the water level eta (in) and the pollutant conservation concentration qc (in) of the sub-grid in the direction, and entering step S4-7; where η (p) is the water level at the grid center p of the sub-grid; η (1) is the water level at the grid center of the first grid; η (2) is the water level at the center of the submesh closest to the submesh in the second grid, i.e., the water level at the center of the second grid; qc (p) is the contaminant conservation concentration at the grid center of the first grid; qc (1) is the contaminant-conservative concentration at the grid center of the first grid; qc (2) is the contaminant conservative concentration at the center of the submesh closest to the submesh in the second grid, i.e., the contaminant conservative concentration at the center of the second grid;
s4-7, according to the formula
Figure GDA0002543026280000104
Figure GDA0002543026280000105
Figure GDA0002543026280000106
Figure GDA0002543026280000111
Obtaining water level gradient grad η (i, j, is, js) and pollutant concentration gradient gradqc (i, j, is, js) of the sub-grid of the leaf grid with the lowest division level, wherein η (i, j, is, js) is the elevation of the sub-grid (i, j, is, js), ηeast、ηwest、ηnorthAnd ηsouthThe water levels of the east, west, north and south directions of the sub-grids (i, j, is, js) are respectively; qc (i, j, is, js) is the contaminant concentration of the subgrid (i, j, is, js); qc is a product ofeast、qcwest、qcnorthAnd qcsouthThe pollutant conservation concentrations of the east, west, north and south directions of the sub-grids (i, j, is, js) are respectively.
The specific method of step S5 includes the following substeps:
s5-1, according to the formula
gradΦ(i,j,is,js)＝max(gradη(i,j,is,js),gradqc(i,j,is,js))
Obtaining the value of a parameter grad phi (i, j, is, js); where max (·) is a maximum selection function;
s5-2, judging whether the sub-grid (i, j, is, js) is positioned at a dry-wet boundary, if so, entering the step S5-3; otherwise, entering step S5-4;
s5-3, judging whether the division level of the leaf grid of the sub grid is the maximum division level, if so, maintaining the maximum division level, otherwise, increasing the division level of the leaf grid of the sub grid by one level to obtain a plurality of sub grids after re-division, and entering the step S6; wherein the newly generated state variable of the center of the sub-grid directly inherits the state variable of the center of the mother grid;
s5-4, judging whether the grad phi (i, j, is, js) is larger than the threshold value, if so, entering the step S5-3; otherwise, entering step S5-5;
s5-5, reducing the division level of the leaf grid where the sub grid is located by one level to obtain a plurality of sub grids which are divided again, and entering the step S6; the combined mother grid center state variables are obtained by averaging 4 grid center state variables.
In one embodiment of the invention, as shown in fig. 4, by taking the substance diffusion simulation under the conditions of static water and tri-hump terrain as an example, the static water harmony, the stability and the simulation accuracy of the two-dimensional hydrodynamic water quality model of the method and the traditional adaptive grid are tested. The calculation domain is 75m × 30 m; the bottom elevation calculation formula is as follows:
Figure GDA0002543026280000121
setting the initial water level of the whole calculation domain to be 1.875m, and setting the flow rate to be 0, namely, under the still water condition; the initial conditions of water quality are as follows: at [10m,16m]×[12m,18m]The substance concentration in the region (1) was 1mg/L, and the substance concentration in the other regions was 0. The mesh maximum division level div _ max is 2, and the terrain slope of mesh refinement is set to 0.02(Φ)zb-sub) The absolute thresholds for mesh refinement and coarsening were set to 0.08(Φ), respectivelysub) And 0.05 (. PHI.)coar). In all the examples, the gravity acceleration g is 9.81m/s2The water density rho is 1000kg/m3. And (3) simulating the hydrodynamic water quality process of a calculation domain with t being 0-30 s by using the traditional self-adaptive grid and the method.
The simulation results of the method for the flow velocity and the pollutant concentration at different moments (t is 0s, 10s, 20s and 30s) are shown in fig. 5 and 6, the whole simulation process can be seen from fig. 5, the flow velocity of a calculation domain is always 0, and the method can ensure the still water harmony of the model. As shown in fig. 6, the pollutants gradually diffused around and the concentration gradually decreased with the lapse of time. The grid distribution at different moments is as shown in fig. 7, and it can be seen that the 3 rd hump has all thinned surrounding grids due to the larger terrain gradient and remains unchanged in the whole simulation process; when t is 10s, the pollutant gradually diffuses to the periphery, the area where the pollutant is located has a larger concentration gradient, the grid is at the maximum division level, when t is 20s, the concentration gradient of the area where the pollutant is located gradually decreases as the pollutant continues to diffuse to the periphery, and the number of the divided grids gradually decreases; when t is 30s, the concentration gradient of the region where the pollutant is located is smaller than the set coarsening threshold, and the grid division level is changed into 0; the method can refine the grids in the area with larger terrain gradient, can self-adaptively adjust the size of the grids according to the water level and the pollutant concentration gradient, and can ensure the still water harmony of the model and the simulation precision of the model in the calculation process.
The simulation results of the method for the pollutant concentration and flow rate at different times (t ═ 0s, 10s, 20s, and 30s) are shown in fig. 8 and 9, and as time goes on, the pollutants gradually diffuse around, and the concentration gradually decreases. It can be seen from fig. 9 and 10 that the simulated flow rate of the method is not 0, and particularly, the water flow around the 3 rd hump is more obvious, because at the initial moment, a dry-wet boundary exists around the 3 rd hump, the area grid can be refined in the simulation process, the sub-grid elevation after refinement is obtained by using an interpolation equation, the sub-grid elevation and the leaf grid elevation obtained by interpolation have a certain difference, in order to ensure the conservation of mass, the water level of the sub-grid is inconsistent with the water level of the neighbor grid, the still water disturbance is generated under the action of gravity, and the model still water harmony is damaged.

Claims (2)

1. A hydrodynamic water quality model self-adaptive grid generation method is characterized by comprising the following steps:
s1, generating a plurality of leaf grids covering the calculation domain, and dividing the leaf grids into a plurality of sub-grids according to the initial division level of the leaf grids; wherein the initial partition level is a maximum partition level; wherein the leaf grid is a maximum grid cell;
s2, acquiring the terrain gradient of the sub-grid; acquiring the relative position relation between the boundary seed points of the target area and the center of the sub-grid;
s3, selecting leaf grids according to the terrain gradient of the sub-grids and the relative position relation between the boundary seed points of the target area and the centers of the sub-grids, and adjusting the division level of the selected leaf grids to be the lowest division level;
s4, acquiring the water level gradient and the pollutant concentration gradient of the sub-grid of the leaf grid which is not at the maximum division level;
s5, adjusting the division level of the corresponding leaf grid again according to the water level gradient, the pollutant concentration gradient and the dry and wet boundary to obtain a plurality of sub-grids after re-division;
s6, judging whether the size of the sub grid of each leaf grid is 2 times, 1 time or 1/2 times of the size of the sub grid of the adjacent leaf grid, and if so, entering the step S7; otherwise, go to step S8;
s7, judging whether to continue generating grids, if so, returning to the step S4, and if not, finishing generating grids;
s8, increasing the division level of the adjacent leaf grids which do not meet the multiple relation by one level, then dividing the sub grids again, and returning to the step S6;
the specific method for acquiring the terrain gradient of the sub-grid in step S2 is as follows:
according to the formula
Figure FDA0002543026270000011
Figure FDA0002543026270000012
Figure FDA0002543026270000013
Obtaining a terrain slope gradz of the sub-grid (i, j, is, is)b(i, j, is, is); wherein z isb(i, j, is, js) is the center elevation of the subgrid (i, j, is, is); z is a radical ofb-east、zb-west、zb-northAnd zb-southThe central elevations of the neighbor grids of the sub-grids (i, j, is, is) in the east, west, north and south directions respectively; Δ x is the length of the subgrid (i, j, is, is) in the x-axis direction, and Δ x is Δ x0/Ms，Δx0The length of a leaf grid (i, j) of the ith row and the jth column of the sub grid (i, j, is, is) in the x-axis direction, and Ms is the maximum division level of the leaf grid (i, j) in the x-axis direction; Δ y is the length of the subgrid (i, j, is, is) in the y-axis direction, and Δ y is Δ y0/Ns，Δy0The length of a leaf grid (i, j) where the sub grid (i, j, is, is) is located in the y-axis direction, and Ns is the maximum division level of the leaf grid (i, j) in the y-axis direction;
Figure FDA0002543026270000021
and
Figure FDA0002543026270000022
is an intermediate parameter;
the specific method of the step S4 includes the following sub-steps:
s4-1, judging whether the water depth of any sub grid is smaller than the preset minimum water depth, if so, taking the sub grid as a dry grid, setting the water level gradient and the pollutant concentration of the dry grid to be 0, and entering the step S4-7; otherwise, go to step S4-2;
s4-2, obtaining a grid center p of the sub grid, and obtaining neighbor leaf grids of the sub grid in four directions of east, west, north and south;
s4-3, judging whether the division level of the leaf grid where the sub grid is located is the same as that of the neighbor leaf grid, if so, taking the water level and the pollutant conservation concentration of the neighbor leaf grid as the water level and the pollutant conservation concentration of the sub grid in the direction, and entering the step S4-7; otherwise, entering step S4-4;
s4-4, judging whether the division level of the leaf grid where the sub grid is located is one level lower than that of the neighbor leaf grid, if so, taking the average value of the water levels and the pollutant conservation concentrations of all the sub grids in the neighbor leaf grid as the water level and the pollutant conservation concentration of the sub grid in the direction, and entering the step S4-7; otherwise, entering step S4-5;
s4-5, taking the adjacent leaf mesh of the sub mesh as a first mesh, and taking the leaf mesh which is adjacent to the first mesh and shares a vertex with the sub mesh as a second mesh; judging whether the division level of the leaf grid of the sub-grid is one level greater than that of the first grid or not, and whether the division level of the second grid is one level greater than that of the first grid or not, if so, respectively according to a formula
Figure FDA0002543026270000031
Figure FDA0002543026270000032
Acquiring the water level eta (in) and the pollutant conservation concentration qc (in) of the sub-grid in the direction, and entering step S4-7; otherwise, entering step S4-6; where η (p) represents the water level at the grid center p of the submesh; η (1) is the water level at the grid center of the first grid; η (2) is the water level in the second grid at the center of the sub-grid closest to the sub-grid; qc (p) is the contaminant conservation concentration at the grid center of the first grid; qc (1) is the contaminant-conservative concentration at the grid center of the first grid; qc (2) is the contaminant-conservative concentration at the center of the submesh closest to the submesh in the second grid;
s4-6, respectively according to the formula
Figure FDA0002543026270000033
Figure FDA0002543026270000034
Acquiring the water level eta (in) and the pollutant conservation concentration qc (in) of the sub-grid in the direction, and entering step S4-7; where η (p) is the water level at the grid center p of the sub-grid; η (1) is the water level at the grid center of the first grid; η (2) is the water level at the center of the submesh closest to the submesh in the second grid, i.e., the water level at the center of the second grid; qc (p) is the contaminant conservation concentration at the grid center of the first grid; qc (1) is the contaminant-conservative concentration at the grid center of the first grid; qc (2) is the contaminant conservative concentration at the center of the submesh closest to the submesh in the second grid, i.e., the contaminant conservative concentration at the center of the second grid;
s4-7, according to the formula
Figure FDA0002543026270000035
Figure FDA0002543026270000041
Figure FDA0002543026270000042
Figure FDA0002543026270000043
Obtaining water level gradient grad η (i, j, is, js) and pollutant concentration gradient gradqc (i, j, is, js) of the sub-grid of the leaf grid with the lowest division level, wherein η (i, j, is, js) is the elevation of the sub-grid (i, j, is, js), ηeast、ηwest、ηnorthAnd ηsouthThe water levels of the east, west, north and south directions of the sub-grids (i, j, is, js) are respectively; qc (i, j, is, js) is the contaminant concentration of the subgrid (i, j, is, js); qc is a product ofeast、qcwest、qcnorthAnd qcsouthRespectively the pollutant conservation concentration of the east, west, north and south directions of the sub-grids (i, j, is, js);
the specific method of the step S5 includes the following sub-steps:
s5-1, according to the formula
gradΦ(i,j,is,js)＝max(gradη(i,j,is,js),gradqc(i,j,is,js))
Obtaining the value of a parameter grad phi (i, j, is, js); where max (·) is a maximum selection function;
s5-2, judging whether the sub-grid (i, j, is, js) is positioned at a dry-wet boundary, if so, entering the step S5-3; otherwise, entering step S5-4;
s5-3, judging whether the division level of the leaf grid of the sub grid is the maximum division level, if so, maintaining the maximum division level, otherwise, increasing the division level of the leaf grid of the sub grid by one level to obtain a plurality of sub grids after re-division, and entering the step S6;
s5-4, judging whether the grad phi (i, j, is, js) is larger than the threshold value, if so, entering the step S5-3; otherwise, entering step S5-5;
s5-5, reducing the division level of the leaf grid where the sub grid is located by one level to obtain a plurality of sub grids which are divided again, and entering the step S6.
2. The hydrodynamic water quality model adaptive mesh generation method according to claim 1, wherein the specific method of step S3 comprises the following sub-steps:
s3-1, a will number a1Setting the mark of the sub-grid adjacent to the boundary seed point of the target area; will number a2Setting the marks of the rest sub grids;
s3-2, marking the existence sub-grid as a1Maintaining the division level of the leaf mesh as the maximum division level, and modifying the signs of all the sub-meshes in the leaf mesh to a3；
S3-3, maintaining the division level of the leaf grids with the terrain slopes of all the sub grids larger than the elevation threshold value as the maximum division level, and modifying the marks of the sub grids as a3；
S3-4, marking the existence sub-grid as a2The leaf meshes are selected and the division level of the leaf meshes is adjusted to the lowest division level, and a plurality of new sub-meshes are generated.
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