A method for extracting river vertical circulation based on flow velocity data

Abstract

The present application relates to a method for extracting a river channel vertical circulation based on flow velocity data, comprising the following specific steps: Step 1: prepare basic flow field data; Step 2: obtain a flow velocity vertical line distribution data group; Step 3: obtain the horizontal flow velocity component of the circulation in the key vertical surface; Step 4: convert the horizontal flow velocity component of the circulation in the key vertical surface into the horizontal flow velocity component of the circulation in the target vertical surface; Step 5: construct the vertical flow velocity component of the circulation corresponding to the horizontal flow velocity component of the circulation, and complete the construction of the circulation velocity vector of the vertical line; Step 6: repeat steps 3 to 5 to quantitatively construct the circulation in the target vertical surface; Step 7: store the constructed vertical circulation flow field data on the hard disk, and display it on the computer screen to provide feedback to the user. The present application can accurately extract the circulation in any cross section of various irregular rivers, and has the advantages of strong versatility, high reliability and high accuracy.

Description

Technical Field

[0001] The present application belongs to the field of water conservancy measurement and visualization technology, and in particular, relates to a method for extracting river channel vertical circulation based on flow velocity data. Background Art

[0002] Secondary flow is widely present in natural rivers, mainly including circulation in the horizontal plane and circulation in the vertical plane, which mostly presents an elliptical flow field. Although secondary flow is a relatively weak flow relative to the longitudinal mainstream of the river channel, it plays an important role in the process of river flow morphology, material transport and riverbed evolution. On the one hand, the circulation in the horizontal plane is easy to capture and quantitatively describe because it is more significant. On the other hand, it is not easy to capture and quantitatively describe the circulation in the vertical plane due to its small scale and being covered by the longitudinal flow of the river channel.

[0003] In the cross section of a river channel, the transverse (tangential) flow can be decomposed into two parts: the convection flow part formed by the projection of the longitudinal flow velocity on the cross section, and the circulation flow part formed by the projection of the spatial spiral flow on the cross section. The circulation part is only a component of the transverse flow of the cross section. For a certain height of a vertical line in the target section, the horizontal velocity component (u τ ) can be decomposed into u τ =u con +u circ , where u con represents the horizontal velocity component of the convection part; u circ It is the horizontal velocity component of the circulation part. In the following contents of this specification, the vertical / cross-sectional circulation refers to the circulation part of the lateral flow field of the vertical / cross-sectional surface of the river channel.

[0004] There are few studies on how to extract river channel vertical circulation based on flow velocity data. So far, there is still a lack of a method that can accurately extract complex river channel vertical circulation, and there are few related reports. However, there are many scientific and engineering studies involving river channel vertical circulation. Existing studies mainly use the following two simplified methods:

[0005] The first method is the lateral velocity representation method. Due to the lack of an accurate method to describe the vertical circulation, some researchers rely on experience to use the lateral flow velocity (u τ ) is used to approximate the vertical circulation, so as to further study the interaction between the vertical circulation and river processes. For related literature, see Termini and Piraino [EarthSurf.Process.Landforms, 2011, 36, 244-256], Russell and Vennell [J.Hydraul.Eng., 2019, 145(5):04019012].

[0006] The second method is the lateral velocity decomposition method. For example, the lateral velocity (u τ ) is decomposed into the average value along the water depth and the local deviation from this average value (Δu τ ), and approximate using and Δu τ Represents u τ For related literature, see Bradshaw [Annu. Rev. Fluid Mech., 1987, 19, 53–74], Blanckaert and Graf [J. Hydraul. Eng. 2004, 130 (3), 186–198], and Blanckaert [J. Geophys. Res. 2009, 114, F03015].

[0007] However, for any given river section, these existing simplified methods often fail to effectively capture the vertical circulation or provide an accurate description of them. Especially when the river has irregular solid boundaries and complex river morphology, it is very difficult to extract the circulation in any vertical section from the complex three-dimensional flow field. These practical situations have made it difficult to establish a quantitative response relationship between vertical circulation and river processes, which has restricted the development of river science. Therefore, it is urgent to study a versatile, effective and accurate method for extracting river vertical circulation. Summary of the invention

[0008] The purpose of the embodiments of the present application is to provide a method for extracting river channel vertical circulation based on flow velocity data, so as to solve the defects of similar methods in the current field of river science research in that they are not universal, reliable and accurate.

[0009] To achieve the above objectives, this application provides the following technical solutions:

[0010] The present application provides a method for extracting river channel vertical circulation based on flow velocity data, including the following specific steps:

[0011] Step 1: Prepare basic flow field data, mainly including field observation data and numerical calculation result data;

[0012] Step 2: Use a series of vertical lines to represent a target vertical surface, divide each vertical line equally along the water depth, and perform flow velocity interpolation at the equally divided points to obtain a flow velocity vertical line distribution data set;

[0013] Step 3: For a vertical line in the target facade, based on the velocity vertical line distribution data group, search for the key facade passing through the vertical line, and obtain the horizontal velocity component of the circulation in the key facade;

[0014] Step 4: For a vertical line in the target facade, convert the horizontal velocity component of the circulation in the key facade into the horizontal velocity component of the circulation in the target facade;

[0015] Step 5: For a vertical line in the target vertical plane, construct the vertical velocity component of the circulation corresponding to the horizontal velocity component of the circulation, and complete the construction of the circulation velocity vector of the vertical line;

[0016] Step 6: Repeat steps 3 to 5 to construct the velocity vectors of the circulation of all representative vertical lines in the target facade, combine them, and quantitatively construct the circulation in the target facade;

[0017] Step 7: Store the constructed flow field data of the facade circulation on the hard disk and display it on the computer screen to provide feedback to the user.

[0018] In step 2, a series of vertical lines are used to represent a target elevation and a flow velocity vertical line distribution data set is obtained, which includes the following steps:

[0019] Step 21: For a target elevation, its cross-section line projected on the horizontal plane is represented by AB. AB is divided into N-1 equal sections on the plane, and P1, P2, ..., P N represents equally divided points, each of which represents a vertical line in the target facade, that is, N representative vertical lines of the target facade are obtained;

[0020] Step 22: Divide each vertical line into equal parts along the water depth. For the vertical line l, divide it into nv equal parts along the water depth, and obtain nv+1 equal-division points, which are identified by k=0, 1, ..., nv.

[0021] Step 23: Based on field observation data or numerical simulation results, l At different heights, the velocity components v in the horizontal x and y directions are obtained by interpolation or assignment. x,l,k 、v y,l,k ;

[0022] Step 24: Using v x,l,k , k = 0, 1, ..., nv, forming the vertical distribution of flow velocity in the horizontal x direction; using v y,l,k , k = 0, 1, ..., nv, forming the vertical distribution of flow velocity in the horizontal y direction;

[0023] The velocity vertical distribution data set refers to the distribution of velocity components in the horizontal x and y directions along the vertical water depth, which can describe the magnitude and direction of the horizontal velocity at each height of the vertical line.

[0024] In step 3, searching for a key elevation that passes through the vertical line includes the following steps:

[0025] Step 31: Based on the projected section line of the target facade on the horizontal plane, the angle between the normal direction represented by AB and the horizontal x-axis, represented by α, is used to search for the angle passing through the vertical line P. l Select a suitable search range Δα∈[-θ,+θ] for the key facade, where Δα is the angle between the temporary facade and the normal direction of the target facade, each Δα represents a search direction, and θ is an angle range of 15 to 30°; Use small intervals to continuously change Δα to traverse and search for the key facade within the range of α'∈[α-θ,α+θ];

[0026] Step 32: For a given Δα, pass through the vertical line P l The angle between the normal direction of the temporary facade and the x-axis is α'=α+Δα, using the formula u τ,Δα,k =-v x,l,k sin(α+Δα)+v y,l,k cos(α+Δα) calculates the perpendicular line P in this temporary facade l The lateral velocity at different heights is expressed as u τ,Δα,k express;

[0027] Step 33: According to u τ,Δα,k , k = 0, 1, ..., nv, described by the vertical distribution of the transverse velocity, use the dimensionless rotation intensity calculation formula to calculate the dimensionless rotation intensity II corresponding to the temporary facade Δα ;

[0028] Step 34: Change Δα, repeat steps 32 and 33, perform traversal search within the range of Δα∈[-θ,θ], calculate and record the dimensionless rotation intensity II corresponding to the temporary facade represented by each Δα Δα , record the largest II during the search Δα II max and the corresponding Δα, using Δα circ Expressed by using the horizontal flow velocity u τ Zero Flux Rule, α+Δα circ Corresponding to u τ The zero flux rule of the vertical surface is approximately satisfied, and it corresponds to the vertical line P l The normal direction of the key facade;

[0029] Step 35: On the vertical line P l The horizontal velocity component of the circulation within the key elevation is u * circ,l,k It is approximately equal to the horizontal component of the lateral flow velocity of the vertical surface, using u *τ,l,k Indicates that, using the formula u * circ,l,k ≈u * τ,l,k =[-v x,l,k sin(α+Δα circ )+v y,l,k cos(α+Δα circ )] Calculate u * circ,l,k , that is, to obtain the horizontal velocity component of the circulation in the key facade.

[0030] In step 33, the dimensionless rotation intensity II Δα The calculation formula is In the formula Use the formulas Calculate, Δz k is the thickness of the water layer represented by the kth velocity point on the vertical line, They respectively represent the lateral flow velocity flux along the left and right directions of the current temporary facade.

[0031] In step 34, the horizontal flow velocity u τ The zero flux rule refers to a vertical line P in the target facade. l , the horizontal velocity component u of the transverse flow τ The integral along the water depth h is zero.

[0032] The physical essence of the key facade is the vertical line P on the facade. l The spatial spiral flow near the surface is fully projected, that is, it satisfies u τ Zero flux rule. Due to u con The impact of τ The zero flux rule has the property of being "uniquely satisfied" in the critical facade, which makes u τ The zero flux rule provides a way to determine the critical elevations around the vertical line. In the critical elevations of the vertical line, due to u τ The zero flux rule is satisfied, which means that u circ ≈u τ , which can be used to determine the circulation part of the vertical line within the key facade. τ The zero flux rule provides a way to extract facade circulation.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] The method provided by the present invention has the following three characteristics. First, the basic calculation unit of the method is a single vertical line extending from the river bottom to the water surface. Second, for a vertical line, only the distribution of the horizontal flow velocity (including the flow velocity components in the horizontal x and y directions) along the water depth is required, and the zero flux rule of uτ can be applied to analyze the circulation near the vertical line. Third, the zero flux rule used does not require that the number of closed circulations in the vertical direction is less than or equal to 1. These characteristics make the method provided by the present invention have the following powerful characteristics. First, the method provided by the present invention has no special requirements for the spatial resolution and position of the representative vertical line. It is applicable to any type of facade (the projection of the facade on the horizontal plane can be a straight line or a curve), as long as the facade can be represented by a series of vertical lines. Second, the method has no requirements for the data source. It only needs to have the data of the horizontal flow velocity vertical line distribution to carry out the calculation. The data source can be the velocity field simulated by the three-dimensional mathematical model or the ADV measurement data. Third, in theory, this method is also applicable to extracting the situation where there are multiple closed circulations in the vertical direction.

[0035] Therefore, the method provided by the present invention can accurately extract the circulation in any cross-section of various irregular river channels, and will not be unable to be used under complex river channel conditions like previous similar methods. It has the advantages of strong versatility, high reliability and accuracy. In addition, the method provided by the present invention only needs to use the flow velocity vertical line distribution data and use a single vertical line as the basic unit for analysis and search, which is very simple. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments of the present application will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0037] Figure 1 It is a schematic diagram of the execution process of the method for extracting river channel vertical circulation based on flow velocity data of the present invention.

[0038] Figure 2 It is a schematic diagram of the target elevation and its representative section.

[0039] Figure 3 It is a schematic diagram of the dimensionless rotation intensity calculation and the zero flux rule.

[0040] Figure 4 This is a schematic diagram of the circulation extraction results of a real single river channel cross section.

[0041] Figure 5a and Figure 5b This is a schematic diagram of the results of the circulation extraction of a real complex river cross section (an example of the lower Jingjiang River section). DETAILED DESCRIPTION

[0042] The technical solutions in the embodiments of the present application will be described below in conjunction with the drawings in the embodiments of the present application. It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings.

[0043] The terms "comprises," "comprising," or any other variation thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the process, method, article, or apparatus that includes the element.

[0044] Figure 1 It is a schematic diagram of the execution process of the method for extracting river channel vertical circulation based on flow velocity data of the present invention. Figure 1 middle,

[0045] Step 101: prepare basic flow field data, which mainly includes two types of field observation data or numerical calculation result data. For example, the horizontal flow velocity and its flow direction at each vertical line height can be measured by ADV to obtain the field observation data of each measured vertical line of the river cross section (target elevation). The three-dimensional flow velocity field of the river can be calculated by a three-dimensional hydrodynamic model to obtain the horizontal flow velocity spatial distribution data.

[0046] Step 102: using a series of vertical lines to represent a target vertical surface, dividing each vertical line into equal parts along the water depth, and performing flow velocity interpolation at the equal-division points to obtain a flow velocity vertical line distribution data set;

[0047] Step 103: for a vertical line in the target facade, based on the velocity vertical line distribution data set, search for a key facade passing through the vertical line, and obtain the horizontal velocity component of the circulation in the key facade.

[0048] Step 104: For a vertical line in the target facade, convert the horizontal velocity component of the circulation in the key facade into the horizontal velocity component of the circulation in the target facade.

[0049] Step 105: For a vertical line in the target vertical plane, construct the vertical velocity component of the circulation corresponding to the horizontal velocity component of the circulation, and complete the construction of the circulation velocity vector of the vertical line.

[0050] Step 106: Repeat steps 3 to 5 to construct the velocity vectors of the circulation of all representative vertical lines in the target facade, combine them, and quantitatively construct the circulation in the target facade.

[0051] Step 107: The constructed flow field data (position, flow velocity, etc.) of the facade circulation is stored on a hard disk and displayed on a computer screen to provide feedback to the user.

[0052] Figure 2 is a schematic diagram of the target elevation and its representative cross-section, with some examples of target elevations and target elevation inclinaments. Figure 2 middle,

[0053] Example of target elevations: 1#, 2#, 3#, and 4# target elevations are arranged along the river channel. The plane positions of their cross-section lines projected on the horizontal plane are as follows: Figure 1 #, 2#, 3#, 4# are shown; at the 2# section, the target facade is arranged in three angles, marked with CS1, CS2, and CS3 respectively. It can be seen from the figure that the target facade is arranged in different directions, and the lateral flow field is different;

[0054] Example of dividing the section line equally: the horizontal projection of the target facade numbered 1# is divided equally, that is, the section line AB is divided into N-1 segments on the plane, using P1, P2, ..., P N represents equally divided points, each of which represents a vertical line in three-dimensional space, that is, N representative vertical lines of the target facade are obtained;

[0055] An example of dividing a vertical line equally: a representative vertical line in the target elevation numbered CS2 is equally divided along the water depth. For example, for the vertical line l, it is equally divided into nv parts along the water depth, and nv+1 equally divided points can be obtained (identified by k=0, 1, ..., nv);

[0056] Example of interpolation of flow velocity at the vertical line equal points, based on field observation data or numerical simulation results, l At different heights, the interpolation (or assignment) method is used to obtain the velocity components v in the horizontal x and y directions x,l,k 、v y,l,k ; Then, use v x,l,k (k = 0, 1, ..., nv) constitutes the vertical distribution of flow velocity in the horizontal x direction; using v y,l,k (k=0, 1, ..., nv) constitutes the vertical distribution of flow velocity in the horizontal y direction.

[0057] Figure 3 It is a schematic diagram of the dimensionless rotation intensity calculation and the zero flux rule. Figure 3 middle,

[0058] Passing through the vertical line P l The normal direction of the temporary facade corresponding to Δα is at an angle α'=α+Δα with the horizontal x-axis. τ,Δα,k =-v x,l,k sin(α+Δα)+v y,l,k cos(α+Δα) calculates the perpendicular line P in this temporary facade l The lateral velocity at different heights (using u τ,Δα,k Indicates), such as Figure 3 Left;

[0059] According to u τ,Δα,k The vertical distribution of the transverse velocity described by (k = 0, 1, ..., nv) is firstly calculated using the formula (where Δz k is the thickness of the water layer represented by the kth velocity point on the vertical line) Calculate the lateral velocity flux along the left and right directions of the current temporary facade like Figure 3 Right; then, use the formula Calculate the dimensionless rotation strength II corresponding to the temporary facade Δα .

[0060] For a vertical line P in the target elevation l , the zero flux rule of horizontal flow velocity is converted into: when crossing a vertical line P l In each facade, the integral (or summation) of the lateral flow velocity over the water depth should be zero, which is specifically manifested as the dimensionless rotation intensity reaching the maximum on the searched facade, and the spatial spiral flow can be fully projected on this facade (i.e. the key facade).

[0061] In the method provided by the present invention, for a vertical line in the target facade, the horizontal velocity component of the circulation in the key facade (using u * circ,l,k denoted) into the horizontal velocity component of the circulation in the target facade (using u circ,l,k In the specific implementation, for a vertical line P l , using the formula u circ,l,k =u * circ,l,k cos(Δα circ )≈u * τ,l,k cos(Δα circ ) is used for calculation, the horizontal velocity component of the circulation in the key facade can be converted into the horizontal velocity component of the circulation in the target facade.

[0062] In the method provided by the present invention, for a vertical line in the target facade, a vertical velocity component of the facade circulation corresponding to the horizontal velocity component of the facade circulation is constructed to complete the construction of the velocity vector of the facade circulation of the vertical line. In specific implementation, the vertical component w of the circulation in the target facade can be calculated by means of the mass conservation principle or by interpolation based on the three-dimensional simulation results. circ,l,k For example, when the σ-grid 3D hydrodynamic model is used to calculate the 3D velocity field and extract the vertical circulation of the river channel based on it, for the vertical line P l The vertical level k can be obtained by the conversion formula between the vertical velocity components of the water flow between the vertical σ coordinate system and the z coordinate system. Calculate the vertical component of the facade circulation, where the x-axis is tangential (lateral) to the target facade, ω l,k 、w l,k Respectively represent the vertical line P l The vertical velocity in the z coordinate system at the kth vertical level σ, h l For water depth.

[0063] Figure 4 This is a schematic diagram of the cross-section circulation extraction results of a real single river channel. First, the three-dimensional hydrodynamic model is used to calculate the selected single river channel slightly curved river section ( Figure 2 ) three-dimensional velocity field, and obtain the velocity vertical distribution data set by interpolation; then, the circulation in the 1#, 2#, 3#, and 4# target facades is extracted based on search calculation. As can be seen from the figure, the obtained facade circulation has the characteristics of continuity and smoothness ( Figure 4 ), which is consistent with the general characteristics of water flow and the previous understanding of the morphological laws of secondary flow.

[0064] Figure 5 is a schematic diagram of the results of the cross-sectional circulation extraction of a real complex river (an example of the lower Jingjiang River section). First, the three-dimensional velocity field of the selected complex real river (the lower Jingjiang River section of the middle reaches of the Yangtze River) was calculated using a three-dimensional hydrodynamic model, and the velocity vertical line distribution data set was obtained by interpolation; then, based on the search calculation, the vertical circulation structure in the target vertical surfaces CS1 to CS50 (the cross-sectional plane position and layout are shown in Figure 5) was extracted. Figure 5a ), the cross-sectional circulation extraction results are shown in Figure 5b As can be seen from the figure, the extracted cross-sectional circulation has the characteristics of continuity and smoothness, accurately showing the longitudinal variation law of the cross-sectional circulation as the river channel morphology changes. The extraction results of the vertical circulation of the complex river channel shown in Figure 5 further prove that the method provided by the present invention has the adaptability to the solid boundary of the irregular river channel and the complex river flow conditions, and has the characteristics of universality.

[0065] The above description is only an embodiment of the present application and is not intended to limit the scope of protection of the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the scope of protection of the present application.

Claims

1. A method for extracting river elevation circulation based on flow velocity data, characterized in that: The specific steps include: Step 1: Prepare basic flow field data, mainly including field observation data and numerical calculation result data; Step 2: Use a series of vertical lines to represent a target vertical surface, divide each vertical line equally along the water depth, and perform flow velocity interpolation at the equally divided points to obtain a flow velocity vertical line distribution data set; Step 3: For a vertical line in the target facade, based on the velocity vertical line distribution data group, search for the key facade passing through the vertical line, and obtain the horizontal velocity component of the circulation in the key facade; Step 4: For a vertical line in the target facade, convert the horizontal velocity component of the circulation in the key facade into the horizontal velocity component of the circulation in the target facade; Step 5: For a vertical line in the target vertical plane, construct the vertical velocity component of the circulation corresponding to the horizontal velocity component of the circulation, and complete the construction of the circulation velocity vector of the vertical line; Step 6: Repeat steps 3 to 5 to construct the velocity vectors of the circulation of all representative vertical lines in the target facade, combine them, and quantitatively construct the circulation in the target facade; Step 7: Store the constructed flow field data of the facade circulation on the hard disk and display it on the computer screen to provide feedback to the user.

2. A method for extracting river elevation circulation based on flow velocity data according to claim 1, characterized in that: In step 2, a series of vertical lines are used to represent a target elevation and a flow velocity vertical line distribution data set is obtained, which includes the following steps: Step 21: For a target elevation, its cross-section line projected on the horizontal plane is represented by AB. AB is divided into N-1 equal sections on the plane, and P1, P2, ..., P N represents equally divided points, each of which represents a vertical line in the target facade, that is, N representative vertical lines of the target facade are obtained; Step 22: Divide each vertical line into equal parts along the water depth. For the vertical line l, divide it into nv equal parts along the water depth, and obtain nv+1 equal-division points, which are identified by k=0, 1, ..., nv. Step 23: Based on field observation data or numerical simulation results, l At different heights, the velocity components v in the horizontal x and y directions are obtained by interpolation or assignment. x,l,k 、v y,l,k ; Step 24: Using v x,l,k , k = 0, 1, ..., nv, forming the vertical distribution of flow velocity in the horizontal x direction; using v y,l,k , k = 0, 1, ..., nv, forming the vertical distribution of flow velocity in the horizontal y direction; The velocity vertical distribution data set refers to the distribution of velocity components in the horizontal x and y directions along the vertical water depth, which can describe the magnitude and direction of the horizontal velocity at each height of the vertical line.

3. The method for extracting river elevation circulation based on flow velocity data according to claim 1, characterized in that: In step 3, searching for a key elevation that passes through the vertical line includes the following steps: Step 31: Based on the projected section line of the target facade on the horizontal plane, the angle between the normal direction represented by AB and the horizontal x-axis, represented by α, is used to search for the angle passing through the vertical line P. l Select a suitable search range Δα∈[-θ,+θ] for the key facade, where Δα is the angle between the temporary facade and the normal direction of the target facade, each Δα represents a search direction, and θ is an angle range of 15 to 30°; use a small interval to continuously change Δα in the range of α'∈[α-θ,α+θ] to traverse and search for the key facade; Step 32: For a given Δα, pass through the vertical line P l The angle between the normal direction of the temporary facade and the x-axis is α'=α+Δα, using the formula u τ,Δα,k =-v x,l,k sin(α+Δα)+v y,l,k cos(α+Δα) calculates the perpendicular line P in this temporary facade l The lateral velocity at different heights is expressed as u τ,Δα,k express; Step 33: According to u τ,Δα,k , k = 0, 1, ..., nv, described by the vertical distribution of the transverse velocity, use the dimensionless rotation intensity calculation formula to calculate the dimensionless rotation intensity II corresponding to the temporary facade Δα ; Step 34: Change Δα, repeat steps 32 and 33, perform traversal search within the range of Δα∈[-θ,θ], calculate and record the dimensionless rotation intensity II corresponding to the temporary facade represented by each Δα Δα , record the largest II during the search process Δα II max and the corresponding Δα, using Δα circ Expressed by using the horizontal flow velocity u τ Zero Flux Rule, α+Δα circ Corresponding to u τ The zero flux rule of the vertical surface is approximately satisfied, and it corresponds to the vertical line P l The normal direction of the key facade; Step 35: On the vertical line P l The horizontal velocity component of the circulation within the key elevation is u * circ，l，k It is approximately equal to the horizontal component of the lateral flow velocity of the vertical surface, using u * τ,l,k Indicates that, using the formula u * circ,l,k ≈u * τ,l,k =[-v x,l,k sin(α+Δα circ )+v y,l,k cos(α+Δα circ )] Calculate u * circ,l,k , that is, to obtain the horizontal velocity component of the circulation in the key facade.

4. The method for extracting river elevation circulation based on flow velocity data according to claim 3 is characterized in that: In step 33, the dimensionless rotation intensity II Δα The calculation formula is In the formula Use the formulas Calculate, Δz k is the thickness of the water layer represented by the kth velocity point on the vertical line, Respectively represent the lateral flow velocity flux along the left and right directions of the current temporary facade.

5. The method for extracting river elevation circulation based on flow velocity data according to claim 3, characterized in that: In step 34, the horizontal flow velocity u τ The zero flux rule refers to a vertical line P in the target facade. l , the horizontal velocity component u of the transverse flow τ The integral along the water depth h is zero.

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