Simulation System and Method for Flow Velocity Distribution of a River Channel with Attached Algae in an Open Channel

Abstract

Open-channel epiphytic algae river flow velocity distribution simulation system and method. The model construction unit constructs an epiphytic algae environmental water flow model according to the epiphytic algae water flow structure; the flow velocity calculation unit conducts formula derivation to obtain the analytical solutions of the flow velocity distributions of the epiphytic algae layer and the free water layer; and calculates the flow velocity calculation values according to the analytical solutions of the flow velocity distributions of the epiphytic algae layer and the free water layer; the flow velocity measurement unit conducts experimental setup and measures the flow velocity distributions at different water depths to obtain the flow velocity measurement values; the result verification unit compares the flow velocity calculation values with the flow velocity measurement values to verify the accuracy of the analytical solutions of the flow velocity distributions of the epiphytic algae layer and the free water layer. The present invention divides the water flow into two layers. The epiphytic algae layer is based on the exponential distributions of epiphytic algae resistance, velocity, and Reynolds stress, and the control equation is solved to obtain the analytical solution of the flow velocity distribution of the epiphytic algae layer; the free water layer is based on the first-order closure model of Reynolds stress, and the control equation is solved to obtain the analytical solution of the flow velocity distribution of the free water layer, thereby obtaining a calculation method for the flow velocity distribution of the epiphytic algae environmental water flow.

Description

Technical Field

[0001] The present invention relates to the technical field of river flow velocity distribution, and more specifically, particularly relates to a simulation system and method for the flow velocity distribution of a canal with attached algae in a river channel. Background Art

[0002] Rivers, as the "veins" of the water cycle, provide an effective channel for the transportation of substances and energy. Algae, as an important part of the river ecosystem, play an important role in the maintenance and restoration of rivers. Attached algae have a significant impact on water level, flow velocity, and riverbed resistance by changing the river flow structure. The flow velocity distribution of open-channel flow under the environment of attached algae is an important basic scientific issue.

[0003] Understanding the hydrodynamic characteristics of attached algae helps to optimize water resources and flood management, and has important ecological and engineering significance. Therefore, the research on attached algae has always received much attention. Under the fluctuation of water flow, attached algae produce morphological changes such as bending, thus generating a reconstruction effect. However, there is no good prediction and calculation method for the water flow velocity under the environment of attached algae.

[0004] Therefore, the problems existing in the prior art need to be further improved and developed. Summary of the Invention

[0005] (1) Object of the Invention: To solve the problems existing in the above prior art, the object of the present invention is to provide a simulation system and method for the flow velocity distribution of a canal with attached algae in a river channel.

[0006] (2) Technical Solution: To solve the above technical problems, the present technical solution provides a simulation system for the flow velocity distribution of a canal with attached algae in a river channel, including a model construction unit, a flow velocity calculation unit, a flow velocity measurement unit, and a result verification unit; the model construction unit constructs a water flow model for the attached algae environment according to the water flow structure of the attached algae in the open channel;

[0007] The flow velocity calculation unit conducts formula derivation to obtain the analytical solution of the flow velocity distribution in the attached algae layer and the analytical solution of the flow velocity distribution in the free water layer; and calculates the flow velocity calculated values at different water depths according to the analytical solutions of the flow velocity distribution in the attached algae layer and the free water layer;

[0008] The flow velocity measurement unit conducts experimental setup and measures the flow velocity distribution at different water depths to obtain the flow velocity measured values at different water depths;

[0009] The result verification unit compares the flow velocity calculated values with the flow velocity measured values to verify the accuracy of the analytical solutions of the flow velocity distribution in the attached algae layer and the free water layer.

[0010] Preferably, for the water flow with attached algae, the model construction unit constructs a water flow model for the attached algae environment according to the water flow structure; the water flow model for the attached algae environment includes an attached algae layer and a free water layer from bottom to top.

[0011] Preferably, the flow velocity calculation unit includes an attached algae layer flow velocity distribution analysis module and a free water layer flow velocity distribution analysis module; the attached algae layer flow velocity distribution analysis module and the free water layer flow velocity distribution analysis module respectively conduct the derivation of the flow velocity distribution analysis solution formula, and respectively obtain the flow velocity distribution analysis solution of the attached algae layer and the flow velocity distribution analysis solution of the free water layer, so as to obtain the flow velocity distribution analysis solution at any water depth and calculate the flow velocity distribution at different water depths.

[0012] Preferably, when in the attached algae layer, substitute the flow velocity distribution analysis solution of the attached algae layer to calculate the flow velocity; when in the free water layer, substitute the analysis solution of the flow velocity distribution of the free water layer to calculate the flow velocity, and obtain the flow velocity calculation values at different water depths.

[0013] Preferably, the attached algae layer flow velocity distribution analysis module conducts formula derivation. Based on the relationship between the resistance of the attached algae and the velocity, and the exponential distribution of the Reynolds stress, the flow velocity distribution analysis solution of the attached algae layer is obtained by solving the control equation:

[0014] ,

[0015] where: u v represents the water flow velocity of the attached algae layer; α represents a constant; u * represents the friction velocity; z represents different water level heights in the water body; h v represents the height of the attached algae after bending; g represents the acceleration due to gravity; S f represents the energy slope; C v represents the new dimensionless resistance coefficient; m is the attached algae distribution density; D represents the cross-sectional diameter of the attached algae filaments.

[0016] Preferably, the free water layer flow velocity distribution analysis module conducts formula derivation. Based on the first-order closure model of the Reynolds stress, the flow velocity distribution analysis solution of the free water layer is obtained by solving the control equation:

[0017] ,

[0018] where: u s represents the water flow velocity of the free water layer; α represents a constant; u * represents the friction velocity; g represents the acceleration due to gravity; S f represents the energy slope; C v represents the new dimensionless resistance coefficient; m is the attached algae distribution density; D represents the cross-sectional diameter of the attached algae filaments; k s represents the von Kármán coefficient of the free water layer; z represents different water level heights in the water body; g represents the acceleration due to gravity; S f represents the energy slope; h vIndicates the height of the attached algae after bending.

[0019] Preferably, the flow velocity measurement unit conducts an experiment on the flow velocity distribution of attached algae, measures the flow velocity of water at different heights through a flow velocity measuring instrument, and obtains the flow velocity measurement value.

[0020] Preferably, the root mean square error RMSE, coefficient of determination R 2 , and correlation coefficient R are calculated for the flow velocity measurement values and flow velocity calculation values under each working condition to represent the similarity between the flow velocity measurement values and the flow velocity calculation values.

[0021] Preferably, within the entire water depth range, the flow velocity calculation value coincides with the flow velocity measurement value, and the analytical solutions of the flow velocity distributions of the attached algae layer and the free water layer obtained from the attached algae layer environmental water flow model have good accuracy.

[0022] The simulation method for the flow velocity distribution of a canal with attached algae is applicable to the simulation system for the flow velocity distribution of a canal with attached algae, and specifically includes:

[0023] Step 1: The model construction unit constructs an attached algae environmental water flow model according to the flow structure of the attached algae canal.

[0024] Step 2: The flow velocity calculation unit conducts formula derivation to obtain the analytical solutions of the flow velocity distributions of the attached algae layer and the free water layer; and calculates the flow velocity calculation values at different water depths according to the analytical solutions of the flow velocity distributions of the attached algae layer and the free water layer.

[0025] Step 3: The flow velocity measurement unit conducts test setup and measures the flow velocity distribution at different water depths to obtain the flow velocity measurement values at different water depths.

[0026] Step 4: The result verification unit compares the flow velocity calculation values with the flow velocity measurement values to verify the accuracy of the analytical solutions of the flow velocity distributions of the attached algae layer and the free water layer.

[0027] (III) Beneficial effects: The simulation system and method for the flow velocity distribution of a canal with attached algae in the present invention, by studying that the presence of attached algae has a significant impact on the vertical distribution of the flow structure of the canal, the water flow velocity distribution is divided into two layers. In the attached algae layer, based on the relationship between the resistance of attached algae and velocity and the exponential distribution of Reynolds stress, the analytical solution of the flow velocity distribution of the attached algae layer is obtained by solving the control equation. In the free water layer, based on the first-order closure model of Reynolds stress, the analytical solution of the flow velocity distribution of the free water layer is obtained by solving the control equation. Secondly, the analytical solutions of the flow velocity distributions of the attached algae layer and the free water layer obtained are in good agreement with the results of the actual flow velocity measurement values, and a calculation method for the water flow velocity distribution suitable for the attached algae environment is obtained. Description of the Drawings

[0028] Figure 1It is a schematic structural diagram of the simulation system for the flow velocity distribution in a river channel with epiphytic algae of the present invention;

[0029] Figure 2 It is a schematic structural diagram of the flow model of the water environment with epiphytic algae of the present invention;

[0030] Figure 3 It is a comparison diagram of the distribution of the measured flow velocity and the calculated flow velocity under Condition 1 of the present invention;

[0031] Figure 4 It is a comparison diagram of the distribution of the measured flow velocity and the calculated flow velocity under Condition 2 of the present invention;

[0032] Figure 5 It is a comparison diagram of the distribution of the measured flow velocity and the calculated flow velocity under Condition 3 of the present invention;

[0033] Figure 6 It is a comparison diagram of the distribution of the measured flow velocity and the calculated flow velocity under Condition 4 of the present invention;

[0034] Figure 7 It is a flow chart of the steps of the method for simulating the flow velocity distribution in a river channel with epiphytic algae of the present invention. Detailed implementation manners

[0035] The following further elaborates on the present invention in conjunction with preferred embodiments. More details are set forth in the following description to facilitate a full understanding of the present invention. However, the present invention can obviously be implemented in many other ways different from this description. Those skilled in the art can make similar generalizations and deductions according to the actual application situation without departing from the connotation of the present invention. Therefore, the protection scope of the present invention should not be limited by the content of this specific embodiment.

[0036] The accompanying drawings are schematic diagrams of the embodiments of the present invention. It should be noted that this accompanying drawing is only an example and is not drawn under the condition of equal proportions, and should not be used to limit the actual scope of protection required by the present invention.

[0037] A simulation system for the flow velocity distribution in a river channel with epiphytic algae, as Figure 1 shown, includes a model construction unit, a flow velocity calculation unit, a flow velocity measurement unit, and a result verification unit. The model construction unit constructs a flow model of the water environment with epiphytic algae according to the flow structure of the water in the open channel with epiphytic algae. The flow velocity calculation unit conducts formula derivation to obtain the analytical solutions of the flow velocity distribution in the epiphytic algae layer and the analytical solutions of the flow velocity distribution in the free water layer; and calculates the calculated flow velocity values at different water depths according to the analytical solutions of the flow velocity distribution in the epiphytic algae layer and the free water layer. The flow velocity measurement unit conducts experimental setup and measures the flow velocity distribution at different water depths to obtain the measured flow velocity values at different water depths. The result verification unit compares the calculated flow velocity values with the measured flow velocity values to verify the accuracy of the analytical solutions of the flow velocity distribution in the epiphytic algae layer and the free water layer.

[0038] According to the research results of predecessors, the water flow structure can be divided into two layers, namely the lower attached-algae layer and the upper free-water layer. As Figure 2 shown, for the water flow with attached algae, the model construction unit constructs an attached-algae environment water flow model according to the water flow structure; the attached-algae environment water flow model includes an attached-algae layer and a free-water layer from bottom to top. Among them, h w represents the entire water depth; h v represents the height of the attached algae after bending; h s represents the free-water layer depth; θ represents the average bending angle of the attached algae.

[0039] The flow velocity calculation unit includes an attached-algae layer flow velocity distribution analysis module and a free-water layer flow velocity distribution analysis module; the attached-algae layer flow velocity distribution analysis module and the free-water layer flow velocity distribution analysis module respectively conduct derivations of the flow velocity distribution analysis solution formulas, and respectively obtain the flow velocity distribution analysis solution of the attached-algae layer and the flow velocity distribution analysis solution of the free-water layer, so as to obtain the flow velocity distribution analysis solution at any water depth and calculate the flow velocity distribution at different water depths. When in the attached-algae layer, substitute the flow velocity distribution analysis solution of the attached-algae layer to calculate the flow velocity; when in the free-water layer, substitute the analysis solution of the flow velocity distribution of the free-water layer to calculate the flow velocity, and obtain the flow velocity calculation values at different water depths.

[0040] In the attached-algae layer, the resistance of the algae to the water flow is proportional to the 1.5th power of the flow velocity, and substitute it into the control equation to solve the analytical expression of the flow velocity distribution in the attached-algae layer. In the free-water layer, the Reynolds stress adopts a first-order closure model and is substituted into the control equation for calculation to obtain the analytical solution of the flow velocity distribution in the free-water layer.

[0041] The attached-algae layer flow velocity distribution analysis module conducts formula derivation. Based on the relationship between the resistance of the attached algae and the velocity, and the exponential distribution of the Reynolds stress, the analytical solution of the flow velocity distribution in the attached-algae layer is obtained by solving the control equation. The flow velocity in the attached-algae layer is related to the Reynolds stress, the resistance of the attached algae, and the gravitational component of the water flow. In the attached-algae layer, for a steady uniform flow, the forces among the gravitational component, the Reynolds stress, and the resistance of the attached algae along the flow direction are balanced. Therefore, as shown in formula (1), there is:

[0042] (1),

[0043] Among them: represents the Reynolds stress; z represents different water level heights in the water body; F represents the resistance of the attached algae; ρ represents the density of water; g represents the acceleration due to gravity; S f represents the energy gradient.

[0044] The Reynolds stress is calculated using an exponential model, as shown in formula (2):

[0045] (2),

[0046] where ρ represents the density of water; and respectively represent the pulsation of the longitudinal and vertical flow velocities; α represents a constant; z represents different water levels in the water body; h v represents the height of the epiphytic algae after bending.

[0047] Through force analysis, the shear stress at the top of the epiphytic algae layer (z = h v ) can be obtained. is expressed as , substituting it into formula (2), we get:

[0048] (3),

[0049] where ρ represents the density of water; represents the friction velocity at the top of the epiphytic algae layer; α represents a constant; z represents different water levels in the water body; h v represents the height of the epiphytic algae after bending.

[0050] When the epiphytic algae produce a large bend in the water flow, a quantitative relationship between the resistance and the bending angle is established, as shown in formula (4):

[0051] (4),

[0052] where F represents the resistance of the epiphytic algae; m is the distribution density of the epiphytic algae, that is, the number of epiphytic algae per unit riverbed area; ρ represents the density of water; u v is the time-averaged velocity of the epiphytic algae layer; C d represents the drag coefficient; D is the width of the water-blocking at the front edge of a single plant; C f represents the friction coefficient, C p = πD represents the cross-sectional perimeter of the epiphytic algae filaments; θ represents the average bending angle of the epiphytic algae.

[0053] The drag coefficient is taken as , and the friction coefficient is taken as . Re is the Reynolds number, Re F is the Reynolds number under the action of friction. However, for the water flow scouring condition, the bending angle of the highly bent epiphytic algae reaches 88° - 90°. On the one hand, from the perspective of the formula, when the bending angle approaches 90°, the drag force term in the resistance term of the epiphytic algae is almost zero; on the other hand, the highly flexible epiphytic algae will swing with the bending of the water flow, and the change in its shape and surface area will significantly reduce the effective resistance area, thereby reducing the influence of the drag force. For the friction term, in the friction coefficient , where u vrepresents the time-averaged velocity of the attached algae layer, l represents the arc length from the bottom of the attached algae to the calculation point, υ represents the kinematic viscosity of water. Substituting into formula (4), it can be found that in the case of large-angle bending, the resistance F of the attached algae is approximately proportional to the 1.5th power of u v , so the relationship can be obtained .

[0054] Therefore, the resistance expression can be simplified to . Through the above analysis of the situation of attached algae, its parameter β takes 1.5, thus establishing a new resistance expression, as shown in formula (5):

[0055] (5),

[0056] where ρ represents the density of water; the friction velocity at the top of the attached algae layer. Here, the friction velocity is introduced to satisfy the dimensional balance; C v represents the new dimensionless resistance coefficient; D is the width of the water-blocking at the leading edge of a single plant; u v represents the time-averaged velocity of the attached algae layer.

[0057] By substituting formulas (3) and (5) into formula (1), the following can be obtained:

[0058] (6),

[0059] where: z represents different water level heights in the water body; the friction velocity at the top of the attached algae layer; α represents a constant; h v represents the height of the attached algae after bending; C v represents the new dimensionless resistance coefficient; m is the distribution density of the attached algae; D is the width of the water-blocking at the leading edge of a single plant; u v is the time-averaged velocity of the attached algae layer; g represents the acceleration due to gravity; S f represents the energy slope.

[0060] Solving formula (6) can obtain the analytical solution of the vertical velocity distribution of the attached algae layer:

[0061] (7),

[0062] where: u v represents the water flow velocity of the attached algae layer; α represents a constant; u * represents the friction velocity; z represents different water level heights in the water body; h v represents the height of the attached algae after bending; g represents the acceleration due to gravity; S f represents the energy slope; C vrepresents the new dimensionless drag coefficient; m is the distribution density of periphyton; D represents the cross-sectional diameter of periphyton filaments.

[0063] The free water layer velocity distribution analysis module conducts formula derivation. Based on the first-order closure model of Reynolds stress, the analytical solution of the velocity distribution in the free water layer is obtained by solving the control equations. In the free water layer, since there is no periphyton drag force, as shown in formula (8), the control equation is:

[0064] (8),

[0065] where: represents the Reynolds stress; z represents different water level heights in the water body; ρ represents the density of water; g represents the acceleration due to gravity; S f represents the energy slope.

[0066] where: the Reynolds stress in the free water layer is calculated using the first-order closure model, as shown in formula (9):

[0067] (9),

[0068] where: ρ represents the density of water; k s represents the von Kármán coefficient of the free water layer; u * represents the friction velocity; u s represents the velocity at different heights in the free water layer; z represents different water level heights in the water body.

[0069] Take the first derivative of the Reynolds stress τ formula for the free water layer, as shown in formula (10):

[0070] (10),

[0071] where: ρ represents the density of water; k s represents the von Kármán coefficient of the free water layer; u * represents the friction velocity; u s represents the velocity at different heights in the free water layer; z represents different water level heights in the water body.

[0072] Substitute formula (10) into formula (8) and solve it to obtain:

[0073] (11),

[0074] where: k s represents the von Kármán coefficient of the free water layer; u * represents the friction velocity; z represents different water level heights in the water body; g represents the acceleration due to gravity; S f represents the energy slope; C represents the integration constant, which is solved through boundary conditions.

[0075] At the top of the attached algal layer, i.e., z = h v , the flow velocity of the attached algal layer should be equal to that of the free water layer, and there is u s (h v ) = u v (h v ), thus obtaining:

[0076] (12),

[0077] where: α represents a constant; u * represents the friction velocity; g represents the acceleration due to gravity; S f represents the energy gradient; C v represents the new dimensionless resistance coefficient; m is the distribution density of the attached algae; D represents the cross-sectional diameter of the attached algal filaments; k s represents the von Kármán coefficient of the free water layer; h v represents the height of the attached algae after bending.

[0078] Substituting formula (12) into formula (11) can solve for the analytical solution of the flow velocity distribution in the free water layer, as shown in formula (13):

[0079] (13),

[0080] where: u s represents the flow velocity of the free water layer; α represents a constant; u * represents the friction velocity; g represents the acceleration due to gravity; S f represents the energy gradient; C v represents the new dimensionless resistance coefficient; m is the distribution density of the attached algae; D represents the cross-sectional diameter of the attached algal filaments; k s represents the von Kármán coefficient of the free water layer; z represents different water levels in the water body; g represents the acceleration due to gravity; S f represents the energy gradient; h v represents the height of the attached algae after bending.

[0081] The flow velocity measurement unit conducts an experiment on the flow velocity distribution of the attached algae, measures the flow velocities at different heights through a flow velocity measuring instrument, and obtains the flow velocity measurement values.

[0082] In the present invention, the experiment on the flow velocity distribution of the attached algae is carried out in a test flume. The test flume is an artificially made glass circulating flume, 10 meters long, 0.5 meters wide, and 0.8 meters high. The attached algae grow evenly on the bottom of the riverbed, and the specific parameters in the experiment are shown in Table 1. The flow velocities at different heights are measured through a PIV flow velocity measuring instrument to obtain the actual flow velocity measurement values.

[0083] Table 1 Parameter Table of Attached Algae under Each Working Condition

[0084]

[0085] The result verification unit compares the flow velocity measurement value actually measured by the flow velocity measurement unit with the flow velocity calculation value at the same height calculated by the analytical solution of the flow velocity distribution of the attached algae layer and the free water layer through the flow velocity calculation unit. As Figures 3 - 6 shown. The solid line in the figure represents the flow velocity calculation value calculated by the analytical solution of the flow velocity distribution of the attached algae layer and the free water layer derived from the attached algae layer environmental water flow model, and the hollow circle represents the flow velocity measurement value actually measured in the attached algae flow velocity distribution experiment.

[0086] By calculating the corresponding values of the root mean square error (RMSE), coefficient of determination (R 2 ), and correlation coefficient (R) for the flow velocity measurement values and flow velocity calculation values of each working condition respectively, the similarity between the flow velocity measurement value and the flow velocity calculation value is represented. The error analysis of each working condition is shown in Table 2.

[0087] The root mean square error (RMSE) is shown in formula (14). The root mean square error is used to characterize the fitting degree between the flow velocity calculation value and the flow velocity measurement value. The smaller the root mean square error, the higher the fitting degree between the flow velocity calculation value and the flow velocity measurement value, and the smaller the error between the two.

[0088] (14),

[0089] where: X i , Y i represent the flow velocity measurement value and the flow velocity calculation value respectively, and N represents the total number of data.

[0090] The coefficient of determination (R 2 ) is shown in formula (15). The value range of R² is [0, 1]. The closer R² is to 1, the higher the fitting degree between the flow velocity calculation value and the flow velocity measurement value, and the smaller the error between the two. When R² is equal to 1, it means that the flow velocity calculation value is exactly the same as the flow velocity measurement value; when R² is equal to 0, it means that the flow velocity calculation value is completely different from the flow velocity measurement value.

[0091] (15),

[0092] where: X i , Y i represent the flow velocity measurement value and the flow velocity calculation value respectively, , represent the flow velocity measurement value and the flow velocity calculation value X i , Y iThe mean value, and N represents the total number of data.

[0093] The correlation coefficient (R) is shown in formula (16), and the value range of R is [-1, 1]. When the value of R is closer to 1, it indicates that the correlation degree between the measured flow velocity value and the calculated flow velocity value is stronger, the error between the two is smaller, and they are positively correlated, that is, the measured flow velocity value and the calculated flow velocity value increase / decrease in the same direction; when R is closer to 0, it indicates that the correlation degree between the measured flow velocity value and the calculated flow velocity value is weaker, and the error between the two is larger; when R is closer to -1, it indicates that the correlation degree between the measured flow velocity value and the calculated flow velocity value is stronger, and they are negatively correlated, that is, the measured flow velocity value and the calculated flow velocity value increase / decrease in the opposite direction. When R is equal to 1, it indicates that the calculated flow velocity value and the measured flow velocity value are completely correlated, and they increase / decrease in the same direction; when R is equal to 0, it indicates that the calculated flow velocity value and the measured flow velocity value are completely uncorrelated; when R is equal to -1, it indicates that the calculated flow velocity value and the measured flow velocity value are completely correlated, and they increase / decrease in the opposite direction.

[0094] (16),

[0095] Where: X i and Y i respectively represent the measured flow velocity value and the calculated flow velocity value, and respectively represent the mean values of the measured flow velocity value and the calculated flow velocity value X i and Y i The mean value, and N represents the total number of data.

[0096] Table 2 Error analysis table for each working condition

[0097]

[0098] The results show that within the entire water depth range, the calculated flow velocity value and the measured flow velocity value are basically in agreement, and the analytical solutions of the flow velocity distributions of the epiphytic algal layer and the free water layer obtained by the epiphytic algal layer environmental water flow model of the present invention have good accuracy.

[0099] The method for simulating the flow velocity distribution of an open-channel epiphytic algal river is applicable to the system for simulating the flow velocity distribution of an open-channel epiphytic algal river as Figure 7 shown, and specifically includes the following steps:

[0100] Step 1: The model construction unit constructs an epiphytic algal layer environmental water flow model according to the epiphytic algal open-channel water flow structure.

[0101] Step 2: The flow velocity calculation unit conducts formula derivation to obtain the analytical solutions of the flow velocity distributions in the periphyton layer and the free water layer; and calculates the flow velocity calculation values at different water depths according to the analytical solutions of the flow velocity distributions in the periphyton layer and the free water layer.

[0102] Step 3: The flow velocity measurement unit conducts experimental setup and measures the flow velocity distributions at different water depths to obtain the flow velocity measurement values at different water depths.

[0103] Step 4: The result verification unit compares the flow velocity calculation values with the flow velocity measurement values to verify the accuracy of the analytical solutions of the flow velocity distributions in the periphyton layer and the free water layer.

[0104] For the open-channel periphyton river flow velocity distribution simulation system and method of the present invention, by studying that the presence of periphyton has a significant impact on the vertical distribution of the open-channel flow structure, the water flow velocity distribution is divided into two layers. In the periphyton layer, based on the relationship between periphyton resistance and velocity and the exponential distribution of Reynolds stress, the analytical solution of the flow velocity distribution in the periphyton layer is obtained by solving the control equation. In the free water layer, based on the first-order closure model of Reynolds stress, the analytical solution of the flow velocity distribution in the free water layer is obtained by solving the control equation. Secondly, the obtained analytical solutions of the flow velocity distributions in the periphyton layer and the free water layer are in good agreement with the results of the actual flow velocity measurement values, and a calculation method for the water flow velocity distribution applicable to the periphyton environment is obtained.

[0105] The above content is an illustration of the preferred embodiments of the present invention, which can help those skilled in the art to more fully understand the technical solutions of the present invention. However, these embodiments are only examples and cannot be considered that the specific implementation manners of the present invention are limited to the descriptions of these embodiments. For those of ordinary skill in the technical field to which the present invention belongs, without departing from the inventive concept of the present invention, several simple deductions and transformations can still be made, which should all be regarded as belonging to the protection scope of the present invention.

Claims

1. The open channel algae-growing river flow velocity distribution simulation system is characterized by: It includes a model building unit, a flow rate calculation unit, a flow rate measurement unit and a result verification unit; the model building unit builds a water flow model of the algae environment according to the algae open channel water flow structure; The velocity calculation unit derives formulas to obtain analytical solutions for velocity distribution in the algae layer and in the free water layer. In the algae layer, the resistance of the algae to the water flow is proportional to the 1.5th power of the flow velocity. Based on the relationship between the resistance and velocity of the algae and the exponential distribution of the Reynolds stress, the velocity distribution analytical solution of the algae layer is substituted into the control equation to solve the velocity distribution analytical solution In the free water layer, the Reynolds stress adopts a first-order closed model and is substituted into the control equation for calculation, and the analytical solution of the velocity distribution in the free water layer is obtained. ; Among them: u v represents the water velocity of the algae layer; α represents a constant; u * represents the friction flow velocity; z represents the different water level heights in the water body; h v represents the height of the algae after bending; g represents the acceleration of gravity; S f represents the energy slope; C v represents the new dimensionless drag coefficient; m is the distribution density of the algae; D is the cross-sectional diameter of the algae filaments; u s represents the flow velocity of the free water layer; k s represents the Karman coefficient of the free water layer; and calculating the flow velocity values ​​at different water depths according to the flow velocity distribution analytical solution of the attached algae layer and the free water layer; The flow velocity measurement unit is experimentally constructed and measures the flow velocity distribution at different water depths to obtain flow velocity measurement values ​​at different water depths; The result verification unit compares the calculated flow velocity value with the measured flow velocity value to verify the accuracy of the analytical solution of the flow velocity distribution of the algae layer and the free water layer.

2. The open channel algae-growing river flow velocity distribution simulation system according to claim 1 is characterized in that: For a water flow with algae, the model construction unit constructs a water flow model for an algae-growing environment according to the water flow structure; the water flow model for an algae-growing environment includes an algae-growing layer and a free water layer from bottom to top.

3. The open channel algae-growing river flow velocity distribution simulation system according to claim 1, characterized in that: The flow velocity calculation unit includes an algae layer flow velocity distribution analysis module and a free water layer flow velocity distribution analysis module; the algae layer flow velocity distribution analysis module and the free water layer flow velocity distribution analysis module respectively derive flow velocity distribution analysis solution formulas, and correspondingly obtain the flow velocity distribution analysis solution of the algae layer and the flow velocity distribution analysis solution of the free water layer, thereby obtaining the flow velocity distribution analysis solution at any water depth, and calculating the flow velocity distribution at different water depths.

4. The open channel algae-growing river flow velocity distribution simulation system according to claim 3 is characterized in that: When in the attached algae layer, the analytical solution of the velocity distribution of the attached algae layer is substituted to calculate the velocity; when in the free water layer, the analytical solution of the velocity distribution of the free water layer is substituted to calculate the velocity, and the calculated velocity values ​​of different water depths are obtained.

5. The open channel algae-growing river flow velocity distribution simulation system according to claim 1, characterized in that: The flow rate measurement unit carries out an algae-growing flow rate distribution experiment, measures the water flow rates at different heights through a flow rate measuring instrument, and obtains flow rate measurement values.

6. The open channel algae-growing river flow velocity distribution simulation system according to claim 1, characterized in that: The root mean square error RMSE and determination coefficient R of the velocity measurement and velocity calculation values ​​of each working condition were calculated. 2 , the correlation coefficient R is calculated, which represents the similarity between the flow velocity measurement value and the flow velocity calculation value.

7. The open channel algae-growing river flow velocity distribution simulation system according to claim 6, characterized in that: In the whole water depth range, the calculated flow velocity is consistent with the measured flow velocity. The analytical solution of the flow velocity distribution in the algae layer and the free water layer obtained by the algae layer environmental flow model has good accuracy.

8. A method for simulating flow velocity distribution in an open channel with algae, applicable to a system for simulating flow velocity distribution in an open channel with algae, characterized in that: Specifically include: Step 1, the model building unit builds a water flow model of the algae environment according to the algae open channel water flow structure; Step 2: The velocity calculation unit derives formulas to obtain analytical solutions for the velocity distribution of the algae layer and the free water layer. In the algae layer, the resistance of the algae to the water flow is proportional to the 1.5th power of the flow velocity. Based on the relationship between the resistance and velocity of the algae and the exponential distribution of the Reynolds stress, the velocity distribution of the algae layer is substituted into the control equation to obtain the analytical solution. In the free water layer, the Reynolds stress adopts a first-order closed model and is substituted into the control equation for calculation, and the analytical solution of the velocity distribution in the free water layer is obtained. ; Among them: u v represents the water velocity of the algae layer; α represents a constant; u * represents the friction flow velocity; z represents the different water level heights in the water body; h v represents the height of the algae after bending; g represents the acceleration of gravity; S f represents the energy slope; C v represents the new dimensionless drag coefficient; m is the distribution density of the algae; D is the cross-sectional diameter of the algae filaments; u s represents the flow velocity of the free water layer; k s represents the Karman coefficient of the free water layer; and calculating the flow velocity values ​​at different water depths according to the flow velocity distribution analytical solution of the attached algae layer and the free water layer; Step 3: The flow velocity measurement unit is experimentally constructed and the flow velocity distribution at different water depths is measured to obtain the flow velocity measurement values ​​at different water depths; Step 4: The result verification unit compares the calculated flow velocity value with the measured flow velocity value to verify the accuracy of the analytical solution of the flow velocity distribution of the algae layer and the free water layer.

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