Method and system for calculating flow resistance of branch-type rigid vegetation in main channel area

Abstract

The present application relates to a method and system for calculating the flow resistance of branching rigid vegetation in the main trough area, the method includes determining the volume correction coefficient of the rigid vegetation in the main trough area; determining the area density of the rigid vegetation in the main trough area; determining the hydraulic radius of the rigid vegetation in the main trough area; determining the average flow velocity between the main stems of the rigid vegetation in the main trough area; and determining the flow resistance coefficient of the rigid vegetation in the main trough area. The present application provides good technical support for further understanding the flow resistance coefficient of rigid vegetation under different submerged conditions from the hydraulic theory level.

Description

Technical Field

[0001] The present application relates to the field of vegetation hydraulic calculation, and in particular to a method and system for calculating the water flow resistance of branch-type rigid vegetation in a main channel area. Background Art

[0002] In river ecosystems, the presence of vegetation can slow down the flow of water, reduce the scouring effect of water on the river bank, and protect the river bank soil from erosion, thereby maintaining the integrity of the river ecosystem. Secondly, from the perspective of engineering hydrology, the impact of vegetation on water flow cannot be ignored. In the fields of water conservancy projects and soil and water conservation projects, the water blocking effect of vegetation has an important impact on the safety and stability of the project. For example, in river management projects, planting vegetation to slow down the flow of water and reduce the scouring effect of water on the river bank is a common engineering measure. At this time, understanding the calculation method of the water flow resistance coefficient of rigid vegetation is of great significance for accurately evaluating the water blocking effect of vegetation and rationally designing engineering plans. In the past, the calculation of the water flow resistance of rigid vegetation such as shrubs was often obtained by generalizing it into a cylindrical rod-shaped structure to obtain a conventional resistance coefficient, and the water blocking effect caused by the branching of rigid vegetation was rarely considered. Therefore, comprehensively considering the influence of vegetation morphological parameters, vegetation density and quantity, water flow conditions (such as water depth, flow velocity, etc.) on the water flow resistance coefficient of branching rigid vegetation can further improve the calculation accuracy in the field of vegetation hydraulics, and can also provide important technical basis for the engineering design and optimization of vegetated river sections. Summary of the invention

[0003] The purpose of the embodiments of the present application is to provide a method and system for calculating the water flow resistance of branching rigid vegetation in the main channel area, so as to provide technical support for river ecological protection and bank slope protection.

[0004] To achieve the above objectives, this application provides the following technical solutions:

[0005] In a first aspect, an embodiment of the present application provides a method for calculating the water flow resistance of branch-type rigid vegetation in a main channel area, comprising the following steps:

[0006] Step 1: Determine the rigid vegetation volume correction coefficient in the main trough area;

[0007] Step 2: Determine the rigid vegetation area density in the main trough area;

[0008] Step 3: Determine the hydraulic radius of rigid vegetation in the main trough area;

[0009] Step 4: Determine the average flow velocity between the main stems of rigid vegetation in the main trough area;

[0010] Step 5: Determine the water flow resistance coefficient of the rigid vegetation in the main trough area.

[0011] The specific method for determining the rigid vegetation volume correction coefficient of the main trough area is:

[0012] Actual water blocking area and the water blocking area of ​​the trunk There exists The conversion relationship, is the volume correction factor of branching rigid vegetation, and the volume correction factor of branching rigid vegetation It is expressed as the ratio of the volume of vegetation to the volume of a cylindrical rod with the same diameter under the same flooding conditions, that is, , where It is the volume of rigid vegetation flooded under a certain flood depth condition; is the flooded volume of the cylindrical rod under the same flooding depth, and All of them are obtained through indoor experimental measurements.

[0013] The determination of the rigid vegetation area density in the main trough area is specifically as follows: It represents the area occupied by the rigid vegetation stems on the unit bed surface. For a rectangular uniformly distributed vegetation array, the density is given by To calculate, where: and Represents the longitudinal and transverse center distances of adjacent vegetation stems, It is the horizontal cross-sectional area of ​​a single plant, measured through indoor experiments.

[0014] The determination of the rigid vegetation hydraulic radius of the main trough area is specifically as follows: considering the vegetation in the main trough area, in the non-flooded condition, the flooded water depth of the vegetation With water depth If they are equal, the volume occupied by the fluid per unit bed surface can be expressed as , the frontal projection area of ​​vegetation on the unit bed surface , where is the number of vegetation per unit bed surface, , is the bottom diameter of the rigid vegetation, and the bottom diameter of the rigid vegetation is approximately the same as the top diameter. and The results are obtained through indoor experimental measurements. The hydraulic radius of the rigid vegetation in the main trough area represents the ratio of the volume occupied by the fluid on the unit bed surface to the effective water-blocking area of ​​the prototype vegetation, which is .

[0015] The method of determining the average flow velocity between the main stems of the rigid vegetation in the main trough area is specifically as follows: According to the subtraction of the cross-sectional area and the effective water-blocking area of ​​vegetation, the flow area of ​​water on the unit bed surface is , where is the width of the main trough area, and the average flow velocity between the main stems of rigid vegetation is obtained through indoor experimental measurements. , where It is the average flow velocity in the section where the rigid vegetation is located, measured through indoor experiments.

[0016] The determination of the flow resistance coefficient of the rigid vegetation in the main trough area is specifically as follows: for rigid vegetation with many branches, a volume correction coefficient is introduced: Then, the flow resistance of a single rigid plant is expressed as , where is the water flow resistance coefficient of the rigid vegetation in the main channel area, is the fluid density, and the component of gravity on the unit bed surface along the flow direction is , where is the bed surface gradient, obtained through indoor experimental measurement, based on the force balance , sorted, .

[0017] In a second aspect, an embodiment of the present application provides a system for calculating the water flow resistance of branching rigid vegetation in a main trough area, comprising:

[0018] A correction coefficient determination module is used to determine the correction coefficient of the rigid vegetation volume in the main trough area;

[0019] Area density determination module, used to determine the rigid vegetation area density in the main trough area;

[0020] A hydraulic radius determination module is used to determine the hydraulic radius of rigid vegetation in the main trough area;

[0021] The module for determining the average flow velocity is used to determine the average flow velocity between the main stems of rigid vegetation in the main trough area;

[0022] The water flow resistance coefficient determination module is used to determine the water flow resistance coefficient of the rigid vegetation in the main trough area.

[0023] In a third aspect, an embodiment of the present application provides a computer-readable storage medium, which stores a program code. When the program code is executed by a processor, the steps of the method for calculating the water flow resistance of branch-type rigid vegetation in the main slot area are implemented as described above.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] This application relies on the morphological characteristic parameters of branched rigid vegetation and the experimental environment and water flow conditions (water depth, flow velocity, etc.) of the main trough area and other measured data. By introducing the volume correction parameters of branched rigid vegetation, the previous method of simply generalizing rigid vegetation into cylindrical rods has been further optimized, which can improve the accuracy of the calculation of water flow resistance of branched rigid vegetation in the main trough area. The calculation data is sufficient, the method mechanism is clear, the implementation process is clear, and the technical means are feasible. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] 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.

[0027] Figure 1 It is a flow chart of the method of the present invention.

[0028] Figure 2 It is a calculation result diagram of the present invention. DETAILED DESCRIPTION

[0029] 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.

[0030] 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.

[0031] The terms "first", "second", etc. are only used to distinguish one entity or operation from another entity or operation, and should not be understood as indicating or implying relative importance, nor should they be understood as requiring or implying any such actual relationship or order between these entities or operations.

[0032] like Figure 1As shown, the present invention provides a method for calculating the water flow resistance of branching rigid vegetation in the main trough area, which specifically includes the steps of determining the volume correction coefficient of the rigid vegetation in the main trough area, determining the area density of the rigid vegetation in the main trough area, determining the hydraulic radius of the rigid vegetation in the main trough area, determining the average flow velocity between the main stems of the rigid vegetation in the main trough area, and determining the water flow resistance coefficient of the rigid vegetation in the main trough area.

[0033] Step 1: Determine the rigid vegetation volume correction coefficient in the main trough area;

[0034] For branched single rigid vegetation, the actual water blocking area Often with the main trunk water blocking area By introducing the rigid vegetation volume correction factor Calculate, that is , where The volume ratio can better quantify the impact of volume unevenness. It is expressed as the ratio of the volume of vegetation to the volume of a cylindrical rod with the same diameter under the same flooding conditions, that is, , where It is the volume of rigid vegetation flooded under a certain flood depth condition; is the flooded volume of the cylindrical rod under the same flooding depth, and All of these can be measured through indoor experiments.

[0035] Step 2: Determine the rigid vegetation area density in the main trough area;

[0036] For a rectangular uniformly distributed vegetation array, the rigid vegetation area density in the main slot area can be obtained by To calculate, where: and Represents the longitudinal and transverse center distances of adjacent vegetation stems, It is the horizontal cross-sectional area of ​​a single plant, which can be measured through indoor experiments.

[0037] Step 3: Determine the hydraulic radius of rigid vegetation in the main trough area;

[0038] In non-flooded conditions, the depth of water inundated with vegetation With water depth The volume occupied by the fluid per unit bed surface can be expressed as , the frontal projection area of ​​vegetation on the unit bed surface , where is the number of vegetation per unit bed surface, , is the bottom diameter of the rigid vegetation, and it is assumed that the bottom diameter of the rigid vegetation is approximately the same as the upper part. and The hydraulic radius of the rigid vegetation in the main trough area represents the ratio of the volume occupied by the fluid on the unit bed surface to the effective water-blocking area of ​​the prototype vegetation, which is .

[0039] Step 4: Determine the average flow velocity between the main stems of rigid vegetation in the main trough area;

[0040] The water flow area can be obtained by subtracting the cross-sectional area from the effective water blocking area of ​​vegetation. , then the flow area of ​​water per unit bed surface is , where is the width of the main trough area, which can be measured through indoor experiments. The average flow velocity between the main stems of rigid vegetation is , where It is the average flow velocity in the section where the rigid vegetation is located, which can be measured through indoor experiments.

[0041] Step 5: Determine the flow resistance coefficient of rigid vegetation in the main trough area

[0042] For rigid vegetation with many branches, the flow resistance of a single rigid vegetation can be expressed as , where is the water flow resistance coefficient of the rigid vegetation in the main trough area, and other symbols are the same as before. The component of gravity along the flow direction on the unit bed surface is , where is the bed surface gradient, which can be measured through indoor experiments. , sorted out, .

[0043] The specific steps of the embodiment are as follows:

[0044] Step 1: First, select typical branched rigid plants from the plain river channel in the lower reaches of the Yangtze River as prototype test objects, trim the plants to ensure that the length of the branches is as consistent as possible, and adjust the stem diameter of the experimental objects. Take measurements and calculate horizontal cross-sectional area It should be noted that in order to conduct comparative tests, smooth cylindrical rods with the same stem diameter and height should be selected as control test objects. Secondly, the longitudinal and transverse stem center distances of adjacent rigid vegetation in the indoor open channel water tank and the number of vegetation per unit bed surface were measured and calculated as , and .according to Calculate the distribution density of branched rigid vegetation .

[0045] Step 2: First, measure the width of the test water tank in the open channel. and bottom gradient Secondly, measure the submerged volume of the prototype plant corresponding to the water depth. Similarly, the submerged volume of the control test subjects at the same water depth was measured. In addition, the average flow velocity of the observation section of the prototype test object was obtained through the water tank test. .according to Calculate the volume correction coefficient of branched rigid vegetation .

[0046] Step 3: Based on the volume correction coefficient of branching rigid vegetation obtained in steps 1 and 2 above and branching rigid vegetation distribution density ,according to Calculate the hydraulic radius of branched rigid vegetation .

[0047] Step 4: Based on the results of steps 1 to 3 above and the measured parameter data, Calculate the average flow velocity between the main stems of rigid vegetation in the main trough area .

[0048] Step 5: Based on the results of steps 1 to 4 above and the measured parameter data, Calculation of the flow resistance coefficient of rigid vegetation in the main channel area . Multiple groups of test results and calculation results are combined in Figure 2 It can be seen that the calculated value is in good agreement with the measured value.

[0049] The embodiment of the present application provides a system for calculating the water flow resistance of branch-type rigid vegetation in a main trough area, comprising:

[0050] A correction coefficient determination module is used to determine the correction coefficient of the rigid vegetation volume in the main trough area;

[0051] Area density determination module, used to determine the rigid vegetation area density in the main trough area;

[0052] A hydraulic radius determination module is used to determine the hydraulic radius of rigid vegetation in the main trough area;

[0053] The module for determining the average flow velocity is used to determine the average flow velocity between the main stems of rigid vegetation in the main trough area;

[0054] The water flow resistance coefficient determination module is used to determine the water flow resistance coefficient of the rigid vegetation in the main trough area.

[0055] An embodiment of the present application provides a computer-readable storage medium storing program codes. When the program codes are executed by a processor, the steps of the method for calculating the water flow resistance of branch-type rigid vegetation in a main slot area as described above are implemented.

[0056] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present application may adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes.

[0057] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0058] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0059] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0060] In a typical configuration, a computing device includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0061] The memory may include non-permanent memory in a computer-readable medium, random access memory (RAM) and / or non-volatile memory in the form of read-only memory (ROM) or flash RAM. The memory is an example of a computer-readable medium.

[0062] Computer readable media include permanent and non-permanent, removable and non-removable media that can be implemented by any method or technology to store information. Information can be computer readable instructions, data structures, program modules or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technology, compact disk read-only memory (CD-ROM), digital versatile disk (DVD) or other optical storage, magnetic cassettes, magnetic tape magnetic disk storage or other magnetic storage devices or any other non-transmission media that can be used to store information that can be accessed by a computing device. As defined herein, computer readable media does not include temporary computer readable media (transitory media), such as modulated data signals and carrier waves.

[0063] The above description is only an embodiment of the present application and is not intended to limit the protection scope 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 protection scope of the present application.

Claims

1. A method for calculating the flow resistance of branch-type rigid vegetation in the main channel area, characterized in that: The following steps are involved: Step 1: Determine the rigid vegetation volume correction coefficient in the main trough area; Step 2: Determine the rigid vegetation area density in the main trough area; Step 3: Determine the hydraulic radius of rigid vegetation in the main trough area; Step 4: Determine the average flow velocity between the main stems of rigid vegetation in the main trough area; Step 5: Determine the water flow resistance coefficient of the rigid vegetation in the main trough area; The specific method for determining the rigid vegetation volume correction coefficient of the main trough area is: Actual water blocking area and the water blocking area of ​​the trunk There exists The conversion relationship, is the volume correction factor of branching rigid vegetation, and the volume correction factor of branching rigid vegetation It is expressed as the ratio of the volume of vegetation to the volume of a cylindrical rod with the same diameter under the same flooding conditions, that is, , where It is the volume of rigid vegetation flooded under a certain flood depth condition; is the flooded volume of the cylindrical rod under the same flooding depth, and All of them are obtained through indoor experimental measurements; The method of determining the average flow velocity between the main stems of the rigid vegetation in the main trough area is specifically as follows: According to the subtraction of the cross-sectional area and the effective water-blocking area of ​​vegetation, the flow area of ​​water on the unit bed surface is , where is the width of the main trough area, and the average flow velocity between the main stems of rigid vegetation is obtained through indoor experimental measurements. , where is the average flow velocity in the section where the rigid vegetation is located, measured through indoor experiments; The determination of the flow resistance coefficient of the rigid vegetation in the main trough area is specifically as follows: for rigid vegetation with many branches, a volume correction coefficient is introduced: Then, the flow resistance of a single rigid plant is expressed as , where is the water flow resistance coefficient of the rigid vegetation in the main channel area, is the fluid density, and the component of gravity on the unit bed surface along the flow direction is , where is the bed surface gradient, obtained through indoor experimental measurement, based on the force balance , sorted, .

2. A method for calculating the flow resistance of branch-type rigid vegetation in the main channel area according to claim 1, characterized in that: The determination of the rigid vegetation area density in the main trough area is specifically as follows: It represents the area occupied by the rigid vegetation stems on the unit bed surface. For a rectangular uniformly distributed vegetation array, the density is given by To calculate, where: and Represents the longitudinal and transverse center distances of adjacent vegetation stems, It is the horizontal cross-sectional area of ​​a single plant, measured through indoor experiments.

3. A method for calculating the flow resistance of branch-type rigid vegetation in the main channel area as claimed in claim 2, characterized in that: The determination of the rigid vegetation hydraulic radius of the main trough area is specifically as follows: considering the vegetation in the main trough area, in the non-flooded condition, the flooded water depth of the vegetation With water depth If they are equal, the volume occupied by the fluid per unit bed surface can be expressed as , the frontal projection area of ​​vegetation on the unit bed surface , where is the number of vegetation per unit bed surface, , is the bottom diameter of the rigid vegetation, and the bottom diameter of the rigid vegetation is approximately the same as the top diameter. and The results are obtained through indoor experimental measurements. The hydraulic radius of the rigid vegetation in the main trough area represents the ratio of the volume occupied by the fluid on the unit bed surface to the effective water-blocking area of ​​the prototype vegetation, which is .

4. A system for calculating the water flow resistance of branch-type rigid vegetation in the main channel area, used to implement the method according to any one of claims 1 to 3, characterized in that: include, A correction coefficient determination module is used to determine the correction coefficient of the rigid vegetation volume in the main trough area; Area density determination module, used to determine the rigid vegetation area density in the main trough area; A hydraulic radius determination module is used to determine the hydraulic radius of rigid vegetation in the main trough area; The average flow velocity determination module is used to determine the average flow velocity between the main stems of rigid vegetation in the main trough area; The water flow resistance coefficient determination module is used to determine the water flow resistance coefficient of the rigid vegetation in the main trough area.

5. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores program codes, and when the program codes are executed by a processor, the steps of the method for calculating the water flow resistance of branch-type rigid vegetation in the main groove area according to any one of claims 1 to 3 are implemented.

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