Simulation method for floating process of river floaters

Abstract

The invention discloses a method for simulating the floating process of river floaters, and belongs to the field of simulation of the floating process of the river floaters, and the method comprises the following steps: setting the initial condition water temperature of a river, and obtaining the density and the dynamic viscosity of water at the current temperature according to the initial condition water temperature; obtaining the particle size and the density of the floating object, and calculating the settling velocity and the particle settling time of the floating object according to the particle size and the density of the floating object, the density of the water at the current temperature and the dynamic viscosity of the water; according to the settling velocity and the particle settling time of the floaters, simulating the moving, distributing and settling processes of the floaters in the river channel based on the hydrodynamic characteristics and the turbulent energy variation in the river channel. The method solves the problem that the existing method cannot simulate the floating, moving, distributing and settling process of the floating object in the river channel.

Description

Technical Field

[0001] The invention belongs to the field of simulation of floating process of river floating objects, and in particular relates to a method for simulating floating process of river floating objects. Background Art

[0002] Floating objects are solid waste that rely on buoyancy on the surface of water bodies, including logs, branches, fallen leaves, straw, platycodon plastic products, etc. Floating objects such as fallen leaves and branches can serve as nutrients for fish, etc., and have a certain impact on the choice of fish habitats and the migration routes of fish populations. Studying the movement and distribution of floating objects will help to better understand the movement and distribution of fish. Better protect the survival of fish. When regulating the waterway, it can meet the needs of navigation and not affect the life of fish.

[0003] Currently available numerical simulation software such as Fluent and Flow3D can simulate the hydrodynamic characteristics of the river under various complex conditions, sediment transport, etc. However, there are few studies on the numerical simulation of adding floating objects in the river and subsequent post-processing. Summary of the invention

[0004] In view of the above-mentioned deficiencies in the prior art, a method for simulating the floating process of floating objects in a river provided by the present invention solves the problem that the prior methods cannot simulate the floating, movement, distribution and sedimentation process of floating objects in a river.

[0005] In order to achieve the above-mentioned invention object, the technical solution adopted by the present invention is: a method for simulating the floating process of river floating objects, comprising the following steps:

[0006] S1. Set the initial condition water temperature of the river channel, and obtain the density of water and the dynamic viscosity of water at the current temperature according to the initial condition water temperature;

[0007] S2, obtaining the particle size and density of the floating objects, and calculating the settling velocity and particle settling time of the floating objects according to the particle size, density, density of water at the current temperature and dynamic viscosity of water;

[0008] S3. According to the settling velocity of floating objects and the particle settling time, based on the hydrodynamic characteristics and turbulent kinetic energy changes in the river, the movement, distribution and sedimentation process of floating objects in the river are simulated.

[0009] Furthermore, the step S1 is specifically as follows:

[0010] S101, setting the initial condition water temperature of the river channel, and querying the density of water at the current temperature based on the corresponding relationship between water temperature and density according to the initial condition water temperature;

[0011] S102. Calculate the dynamic viscosity of water at the current temperature according to the density of water at the current temperature:

[0012]

[0013]

[0014] Where mu is the kinematic viscosity of water at the current temperature; nu is the dynamic viscosity of water at the current temperature; ρ 水 is the density of water at the current temperature; T is the initial water temperature.

[0015] Furthermore, the expressions for the settling velocity of the floating objects and the particle settling time in step S2 are respectively:

[0016]

[0017]

[0018]

[0019] ws=|4*g*d 漂 *(ρ 水 -ρ 漂 )|-3*C d *ρ 水 *ws 2

[0020] Among them, t au is the particle settling time of floating objects; ρ 漂 is the density of floating objects; d 漂 is the floating particle size; ρ 水 is the density of water at the current temperature; C d is the resistance coefficient of the floating object; ws is the sinking velocity of the floating object; Re is the Reynolds number of the floating object; nu is the dynamic viscosity of water at the current temperature; g is the acceleration due to gravity.

[0021] Furthermore, the step S3 is specifically as follows:

[0022] S301, using numerical simulation software to simulate the river channel, importing river channel hydrodynamic parameters, setting floating time intervals, and simulating the placement of floating objects;

[0023] S302, interpolating the hydrodynamic parameters using an interpolation function, constructing a three-dimensional grid, interpolating the points of the grid in the xyz direction, and calculating the water depth, water surface line, flow velocity and turbulent kinetic energy corresponding to each interpolation point;

[0024] S303, judging whether the turbulent kinetic energy of the grid where the floating object is located is 0 according to the turbulent kinetic energy corresponding to each interpolation point, if so, proceeding to step S304, otherwise, proceeding to step S305;

[0025] S304, setting the new moving speed of the floating object in the X direction, Y direction and Z direction to 0, and proceeding to step S306;

[0026] S305, calculating the new moving speed of the floating object in the X direction, the Y direction and the Z direction, and proceeding to step S306;

[0027] S306, and calculating the position coordinates of the floating object after the floating time interval according to the new moving speed of the floating object in the X direction, the Y direction and the Z direction;

[0028] S307, according to the position coordinates of each floating object after it moves, respectively detect whether the floating object is still moving in the river channel, if so, directly enter step S308, otherwise, take the coordinates of the floating object touching the riverbed or the coordinates of the water surface line during the floating process as the position coordinates of the floating object after it moves, output the floating process of the floating object, and enter step S308;

[0029] S308, determine whether the set experiment end time has been reached, if so, end the process, otherwise, enter step S309;

[0030] S309, determining whether the total amount of floating objects reaches the preset total amount of floating objects, if so, directly returning to step S303, otherwise, proceeding to step S3010;

[0031] S3010, determine whether the time interval from the last time a floating object was placed reaches the preset placement interval, if yes, place a new floating object and return to step S303, otherwise, directly return to step S303.

[0032] Furthermore, the expressions of the new moving speeds of the floating object in the X direction, the Y direction and the Z direction in step S305 are respectively:

[0033]

[0034]

[0035]

[0036]

[0037]

[0038] Among them, u new is the new speed of the floating object in the X direction; u is the speed of the floating object in the X direction; e is a natural constant; σ is an intermediate variable; random is a generated random number; v new is the new speed of the floating object in the Y direction; v is the speed of the floating object in the Y direction; wnew is the new speed of the floating object in the Z direction; w is the speed of the floating object in the Z direction; t ke is the turbulent kinetic energy; d is the differential symbol; t is the time; t au 'The time used to assign the new movement speed; t a is the floating time interval.

[0039] Furthermore, the expression of the position coordinates of the floating object after movement in step S306 is:

[0040] x i =x0+(u+u new )dt

[0041] y i =y0+(v+v new )dt

[0042] z i =z0+(w+w new +ws)dt

[0043] Where xi is the X-axis coordinate of the position of the floating object after it moves; i is the subscript that identifies the new position; x0 is the X-axis coordinate of the original position of the floating object; u new is the new speed of the floating object in the X direction; u is the speed of the floating object in the X direction; y i is the Y-axis coordinate of the position of the floating object after it moves; y0 is the Y-axis coordinate of the original position of the floating object; v new is the new speed of the floating object in the Y direction; v is the speed of the floating object in the Y direction; z i is the Z-axis coordinate of the position of the floating object after it moves; z0 is the Z-axis coordinate of the original position of the floating object; w new is the new moving speed of the floating object in the Z direction; w is the moving speed of the floating object in the Z direction.

[0044] The beneficial effects of the present invention are as follows: the present invention can more accurately simulate the movement and sedimentation laws of floating objects such as leaves in water bodies, simulate and predict floating objects such as leaves in any water body, determine the positions of floating objects such as leaves at any time, and provide technical support for the distribution, convergence and sedimentation of floating objects such as leaves, so as to understand the enrichment and distribution of nutrients. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 The present invention is a flow chart of the method. DETAILED DESCRIPTION

[0046] The specific implementation modes of the present invention are described below so that those skilled in the art can understand the present invention. However, it should be clear that the present invention is not limited to the scope of the specific implementation modes. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the attached claims, these changes are obvious, and all inventions and creations utilizing the concept of the present invention are protected.

[0047] like Figure 1 As shown, in one embodiment of the present invention, a method for simulating the floating process of river floating objects includes the following steps:

[0048] S1. Set the initial condition water temperature of the river channel, and obtain the density of water and the dynamic viscosity of water at the current temperature according to the initial condition water temperature;

[0049] S2, obtaining the particle size and density of the floating objects, and calculating the settling velocity and particle settling time of the floating objects according to the particle size, density, density of water at the current temperature and dynamic viscosity of water;

[0050] S3. According to the settling velocity of floating objects and the particle settling time, based on the hydrodynamic characteristics and turbulent kinetic energy changes in the river, the movement, distribution and sedimentation process of floating objects in the river are simulated.

[0051] In this embodiment, the present invention provides a method for simulating the movement, distribution and settlement process of floating objects such as leaves in a river, including the following steps:

[0052] Step 1: Definition of river water properties

[0053] Define the water properties of the river, including the temperature, density, kinematic viscosity nu and dynamic viscosity mu of the water.

[0054] Step 2: Float Characteristics Definition

[0055] The characteristics of floating objects are defined, and the settling speed, drag coefficient, and particle relaxation time of floating objects such as leaves are calculated based on water temperature, water density, and particle size of floating objects.

[0056] Step 3: Simulate the movement of floating objects such as leaves in water

[0057] Based on the hydrodynamic characteristics and turbulent kinetic energy changes in the river, when the turbulent kinetic energy changes are not 0, the leaves will obtain new speed and position coordinates in the x, y, and z directions, and output when the leaves reach the river bottom and the water surface.

[0058] The step S1 is specifically as follows:

[0059] S101, setting the initial condition water temperature of the river channel, and querying the density of water at the current temperature based on the corresponding relationship between water temperature and density according to the initial condition water temperature;

[0060] S102. Calculate the dynamic viscosity of water at the current temperature according to the density of water at the current temperature:

[0061]

[0062]

[0063] Where mu is the kinematic viscosity of water at the current temperature; nu is the dynamic viscosity of water at the current temperature; ρ 水 is the density of water at the current temperature; T is the initial water temperature.

[0064] The expressions for the settling velocity of the floating objects and the particle settling time in step S2 are:

[0065]

[0066]

[0067]

[0068] ws=|4*g*d 漂 *(ρ 水 -ρ 漂 )|-3*C d *ρ 水 *ws 2

[0069] Among them, t au is the particle settling time of floating objects; ρ 漂 is the density of floating objects; d 漂 is the floating particle size; ρ 水 is the density of water at the current temperature; C d is the resistance coefficient of the floating object; ws is the sinking velocity of the floating object; Re is the Reynolds number of the floating object; nu is the dynamic viscosity of water at the current temperature; g is the acceleration due to gravity.

[0070] The step S3 is specifically as follows:

[0071] S301, using numerical simulation software to simulate the river channel, importing river channel hydrodynamic parameters, setting floating time intervals, and simulating the placement of a number of floating objects;

[0072] S302, interpolating the hydrodynamic parameters using an interpolation function, constructing a three-dimensional grid, interpolating the points of the grid in the xyz direction, and calculating the water depth, water surface line, flow velocity and turbulent kinetic energy corresponding to each interpolation point;

[0073] S303, according to the turbulent kinetic energy corresponding to each interpolation point, determine whether the turbulent kinetic energy of each grid where the floating object is located is 0, if so, proceed to step S304, otherwise, proceed to step S305;

[0074] S304, setting the new moving speed of the floating object in the X direction, Y direction and Z direction to 0, and proceeding to step S306;

[0075] S305, calculating the new moving speed of the floating object in the X direction, the Y direction and the Z direction, and proceeding to step S306;

[0076] S306, and calculating the position coordinates of the floating objects after the floating time interval according to the new moving speeds of each floating object in the X direction, the Y direction and the Z direction;

[0077] S307, according to the position coordinates of each floating object after it moves, respectively detect whether the floating object is still moving in the river channel, if so, directly enter step S308, otherwise, take the coordinates of the floating object touching the riverbed or the coordinates of the water surface line during the floating process as the position coordinates of the floating object after it moves, output the floating process of the floating object, and enter step S308;

[0078] S308, determine whether the set experiment end time has been reached, if so, end the process, otherwise, enter step S309;

[0079] S309, determining whether the total amount of floating objects reaches the preset total amount of floating objects, if so, directly returning to step S303, otherwise, proceeding to step S3010;

[0080] S3010, determine whether the time interval from the last time a floating object was placed reaches the preset placement interval, if yes, place a new floating object and return to step S303, otherwise, directly return to step S303.

[0081] In this embodiment, the numerical simulation software is specifically a simulation tool capable of performing river simulation. In this embodiment, FLOW3D is used for river simulation.

[0082] The expressions of the new moving speeds of the floating objects in the X direction, the Y direction and the Z direction in step S305 are respectively:

[0083]

[0084]

[0085]

[0086]

[0087]

[0088] Among them, u new is the new speed of the floating object in the X direction; u is the speed of the floating object in the X direction; e is a natural constant; σ is an intermediate variable; random is a generated random number; v new is the new speed of the floating object in the Y direction; v is the speed of the floating object in the Y direction; w new is the new speed of the floating object in the Z direction; w is the speed of the floating object in the Z direction; t ke is the turbulent kinetic energy; d is the differential symbol; t is the time; t au 'The time used to assign the new movement speed; t a is the floating time interval.

[0089] The expression of the position coordinates of the floating object after movement in step S306 is:

[0090] x i =x0+(u+u new )dt

[0091] y i =y0+(v+v new )dt

[0092] z i =z0+(w+w new +ws)dt

[0093] Among them, x i is the X-axis coordinate of the position of the floating object after it moves; i is the subscript that identifies the new position; x0 is the X-axis coordinate of the original position of the floating object; u new is the new speed of the floating object in the X direction; u is the speed of the floating object in the X direction; y i is the Y-axis coordinate of the position of the floating object after it moves; y0 is the Y-axis coordinate of the original position of the floating object; v new is the new speed of the floating object in the Y direction; v is the speed of the floating object in the Y direction; z i is the Z-axis coordinate of the position of the floating object after it moves; z0 is the Z-axis coordinate of the original position of the floating object; w new is the new moving speed of the floating object in the Z direction; w is the moving speed of the floating object in the Z direction.

[0094] In this embodiment, step 3 is specifically as follows:

[0095] First, import the river hydrodynamic parameters

[0096] The hydrodynamic parameters of the river obtained in flow3d, the flow velocities u, v, w of each point in the river in the xyz direction, the position coordinates x, y, z of each point, the height of the water surface line in the river, the height of the top of the riverbed, the turbulent kinetic energy of each point in the river, and the change of turbulent kinetic energy of each point, etc. are read by python.

[0097] Then, the hydrodynamic parameters are interpolated using the interpolation function through Python software, a three-dimensional grid is constructed, the points of the grid in the xyz direction are interpolated, and the water depth, water surface line, flow velocity, turbulent kinetic energy and other data corresponding to the interpolation points are calculated.

[0098] Secondly, the movement is judged based on the change in turbulent kinetic energy at the location of the particle. When the change in turbulent kinetic energy is not 0, a new speed is given to floating objects such as leaves in the xyz direction, and a certain limit is imposed on the new speed, with a given time interval of 0.3s. The displacement of the floating object in the xyz direction is calculated based on the speed and time interval, thereby giving the position coordinates of the floating object after movement. The movement in the z direction must take into account the distance of the sedimentation movement.

[0099] Furthermore, detect whether the floating objects are still moving in the river.

[0100] Check whether the position of floating objects is on the horizontal projection of the river channel, extract all the points projected in the water in the horizontal direction, calculate the mode, and discard the mode to remove the points on both sides of the riverbed. Count the highest value of the remaining points to get the position of the water surface line. Extract each point on the riverbed, calculate the height mode and remove the points on both sides of the riverbed, and count the highest value of the remaining points to get the riverbed top elevation.

[0101] Determine whether the horizontal projection of the floating object point is within the horizontal range of the river channel. If it is within the range of the river channel, these points are extracted. In order to remove the points on both sides of the river channel, the elevation mode is extracted for removal. Then judge the remaining points. When the water surface height is 0 or the river bottom elevation is greater than the water surface line, this is a flat land or an area above the water surface, and it is directly output. When the water surface is higher than the river bottom elevation, the output is the new height z. If the new height z is greater than the water surface height, the output reaches the surface. If the new height is less than the river bottom elevation, the output touches the bottom. Finally, the new coordinate points that meet the conditions and the water surface and river bottom elevations are obtained.

[0102] Simulate the placement of floating objects, set the duration of the experiment, set the time interval for recording, set the horizontal coordinates of the placement location, set the number of each placement and the total number. After the placement, the sequence number + 1 continues to be placed until the sequence number reaches the set maximum number. When placing, the z coordinate defaults to the water surface. After the floating object is placed, calculate the new speed and position to make the floating object move, and then check the position of the floating object. Observe whether the floating object has completed sinking or floated to the surface of the water.

Claims

1. A method for simulating the floating process of floating objects in a river, characterized in that: The following steps are involved: S1. Set the initial condition water temperature of the river channel, and obtain the density of water and the dynamic viscosity of water at the current temperature according to the initial condition water temperature; S2, obtaining the particle size and density of the floating objects, and calculating the settling velocity and particle settling time of the floating objects according to the particle size, density, density of water at the current temperature and dynamic viscosity of water; S3. According to the settling velocity of floating objects and the particle settling time, based on the hydrodynamic characteristics and turbulent kinetic energy changes in the river, the movement, distribution and sedimentation process of floating objects in the river are simulated.

2. The method for simulating the floating process of river floating objects according to claim 1, characterized in that: The step S1 is specifically as follows: S101, setting the initial condition water temperature of the river channel, and querying the density of water at the current temperature based on the corresponding relationship between water temperature and density according to the initial condition water temperature; S102. Calculate the dynamic viscosity of water at the current temperature according to the density of water at the current temperature: Where mu is the kinematic viscosity of water at the current temperature; nu is the dynamic viscosity of water at the current temperature; ρ 水 is the density of water at the current temperature; T is the initial water temperature.

3. The method for simulating the floating process of river floating objects according to claim 1, characterized in that: The expressions for the settling velocity of the floating objects and the particle settling time in step S2 are: ws=|4*g*d 漂 *(r 水 -r 漂 )|-3*C d *r 水 *ws 2 Among them, t au is the particle settling time of floating objects; ρ 漂 is the density of floating objects; d 漂 is the floating particle size; ρ 水 is the density of water at the current temperature; C d is the resistance coefficient of the floating object; ws is the sinking velocity of the floating object; Re is the Reynolds number of the floating object; nu is the dynamic viscosity of water at the current temperature; g is the acceleration due to gravity.

4. The method for simulating the floating process of river floating objects according to claim 1, characterized in that: The step S3 is specifically as follows: S301, using numerical simulation software to simulate the river channel, importing river channel hydrodynamic parameters, setting floating time intervals, and simulating the placement of floating objects; S302, interpolating the hydrodynamic parameters using an interpolation function, constructing a three-dimensional grid, interpolating the points of the grid in the xyz direction, and calculating the water depth, water surface line, flow velocity and turbulent kinetic energy corresponding to each interpolation point; S303, judging whether the turbulent kinetic energy of the grid where the floating object is located is 0 according to the turbulent kinetic energy corresponding to each interpolation point, if so, proceeding to step S304, otherwise, proceeding to step S305; S304, setting the new moving speed of the floating object in the X direction, Y direction and Z direction to 0, and proceeding to step S306; S305, calculating the new moving speed of the floating object in the X direction, the Y direction and the Z direction, and proceeding to step S306; S306, and calculating the position coordinates of the floating object after the floating time interval according to the new moving speed of the floating object in the X direction, the Y direction and the Z direction; S307, according to the position coordinates of each floating object after it moves, respectively detect whether the floating object is still moving in the river channel, if so, directly enter step S308, otherwise, take the coordinates of the floating object touching the riverbed or the coordinates of the water surface line during the floating process as the position coordinates of the floating object after it moves, output the floating process of the floating object, and enter step S308; S308, determine whether the set experiment end time has been reached, if so, end the process, otherwise, enter step S309; S309, determining whether the total amount of floating objects reaches the preset total amount of floating objects, if so, directly returning to step S303, otherwise, proceeding to step S3010; S3010, determine whether the time interval from the last time a floating object was placed reaches the preset placement interval, if yes, place a new floating object and return to step S303, otherwise, directly return to step S303.

5. The method for simulating the floating process of river floating objects according to claim 4, characterized in that: The expressions of the new moving speeds of the floating objects in the X direction, the Y direction and the Z direction in step S305 are respectively: Among them, u new is the new speed of the floating object in the X direction; u is the speed of the floating object in the X direction; e is a natural constant; σ is an intermediate variable; random is a generated random number; v new is the new speed of the floating object in the Y direction; v is the speed of the floating object in the Y direction; w new is the new speed of the floating object in the Z direction; w is the speed of the floating object in the Z direction; t ke is the turbulent kinetic energy; d is the differential symbol; t is the time; t au 'The time used to assign the new movement speed; t a is the floating time interval.

6. The method for simulating the floating process of river floating objects according to claim 4, characterized in that: The expression of the position coordinates of the floating object after movement in step S306 is: x i =x0+(u+u new )dt y i =y0+(v+v new )dt With i =z0+(w+w new +ws)dt Among them, x i is the X-axis coordinate of the position of the floating object after it moves; i is the subscript that identifies the new position; x0 is the X-axis coordinate of the original position of the floating object; u new is the new speed of the floating object in the X direction; u is the speed of the floating object in the X direction; y i is the Y-axis coordinate of the position of the floating object after it moves; y0 is the Y-axis coordinate of the original position of the floating object; v new is the new speed of the floating object in the Y direction; v is the speed of the floating object in the Y direction; z i is the Z-axis coordinate of the position of the floating object after it moves; z0 is the Z-axis coordinate of the original position of the floating object; w new is the new moving speed of the floating object in the Z direction; w is the moving speed of the floating object in the Z direction.

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