Sewage draining exit layout optimization method based on Fluent fluid simulation

Abstract

The invention provides a sewage draining exit layout optimization method based on Fluent fluid simulation. The sewage draining exit layout optimization method comprises the following steps: S1, setting an optimization target; s2, a single drain outlet is formed in the center of the bottom of the culture pond and serves as a starting point of layout optimization; s3, evaluating whether the initial layout reaches a set optimization target or not; and S4, by taking the initial sewage draining exit as a circle center, adding sewage draining exits with the same specification one by one in the circumferential direction of the initial sewage draining exit, keeping all the sewage draining exits in the circumferential direction to be distributed at equal intervals, judging whether the new layout reaches a set optimization target or not according to a simulation result, and ending optimization until the sewage draining exit layout which can reach the set optimization target is found. By optimizing the layout and design of the drain outlets, the purpose of rapidly and efficiently discharging pollutants in the culture pond with the minimum number of drain outlets is achieved, the cost effectiveness and the stability of the pond body structure and the culture environment are guaranteed, and green and healthy development of the aquaculture industry is promoted.

Description

Technical Field

[0001] The present invention relates to the technical field of aquaculture, and in particular to a method for optimizing the layout of sewage outlets based on Fluent fluid simulation. Background Art

[0002] As an important part of the global food supply chain, the development and technological innovation of aquaculture are of great significance for ensuring food safety and promoting sustainable agricultural development. This industry not only involves in-depth research in biology and ecology, but also widely integrates modern scientific and technological means such as engineering technology and information technology, aiming to improve production efficiency while ensuring the quality of aquatic products and the harmonious coexistence of the environment. Traditional and modern breeding modes coexist in today's aquaculture practices. On the one hand, we see that earth pond breeding still retains its natural breeding characteristics. Through clever bottom drainage design, it uses physical principles to naturally remove sediments and reduce human interference with the breeding environment. On the other hand, the rise of factory-scale recirculating water aquaculture systems, with its efficient water treatment capacity and environmental control advantages, has greatly improved the breeding density and output efficiency per unit area. The integration of Internet of Things technology has made it possible to monitor water quality in real time and accurately feed, promoting the wave of intelligent breeding.

[0003] However, despite significant technological advances, the field of aquaculture still faces many challenges, especially in the maintenance and management of the aquaculture environment. As the core area for the growth of aquatic organisms, if the waste and unconsumed bait in the aquaculture pond are not effectively cleaned, it will directly affect the water quality, thereby threatening the health and survival rate of the aquaculture organisms. The existing sewage discharge system mostly relies on a single sewage outlet layout. Although the structure is simple, it exposes the shortcomings of low sewage discharge efficiency in practical applications. As an intuitive solution, adding sewage outlets can make up for the lack of sewage discharge efficiency to a certain extent, but the addition of each sewage outlet requires corresponding pipeline laying, maintenance costs and possible construction and renovation costs. Too many sewage outlets will directly increase the economic burden, and will also affect the structural stability of the pond body, and will cause the water in the pond to exchange too quickly during sewage discharge, affecting the stability of water quality parameters such as water temperature and dissolved oxygen content, and have an adverse effect on aquaculture organisms. Summary of the invention

[0004] In order to solve the technical problem of how to improve the sewage discharge efficiency while reducing the number of sewage outlets as much as possible through reasonable layout of sewage outlets, the present invention provides a sewage outlet layout optimization method based on Fluent fluid simulation. By optimizing the layout and design of the sewage outlets, not only can the goal of quickly and efficiently discharging pollutants in the aquaculture pond be achieved with a minimum number of sewage outlets, but also the cost-effectiveness, stability of the pond structure and the aquaculture environment are guaranteed, thereby promoting the green and healthy development of the aquaculture industry.

[0005] The present invention achieves the above technical objectives through the following technical means.

[0006] A method for optimizing the layout of a sewage outlet based on Fluent fluid simulation, characterized in that it comprises the following steps:

[0007] S1: Set optimization goals:

[0008] The optimization goal of the layout of the sewage outlets of the aquaculture pond is to ensure that the volume fraction of pollutants in the aquaculture pond can be reduced to below 0.01% through the layout of the minimum number of sewage outlets within the set sewage discharge cycle;

[0009] S2: Initial layout and simulation analysis:

[0010] A single sewage outlet is set in the center of the bottom of the aquaculture pond as the starting point for layout optimization. Fluent software is used for fluid dynamics simulation to simulate and obtain the curve of the volume fraction of pollutants changing with the sewage discharge time. The specific steps are as follows:

[0011] S2.1: Based on the actual size of the aquaculture pond, the actual location and size of the water inlet, the actual location and size of the sewage outlet, and the actual aquaculture area, a three-dimensional model of the aquaculture pond is established using a three-dimensional modeling software, and the aquaculture area is defined as a fluid domain;

[0012] S2.2: Import the three-dimensional model of the aquaculture pond into the Fluent software and perform structured meshing on the fluid domain;

[0013] S2.3: Select solver and solution method;

[0014] S2.4: Select the turbulence model and set the boundary conditions and physical properties of the fluid domain;

[0015] S2.5: Initialize the boundary and set the calculation time step and iteration number of the Fluent solver to perform the calculation;

[0016] S2.6: Import the calculation results into CFD-post for visualization, and obtain the curve of the volume fraction of pollutants in the aquaculture pond changing with the discharge time;

[0017] S3: Evaluate the initial layout effect:

[0018] According to the simulation results, it is judged whether the initial sewage outlet layout meets the set optimization target. If it does, the initial sewage outlet layout is confirmed to be the optimal solution and the optimization process ends; if it does not, the next optimization process is entered;

[0019] S4: Multiple optimizations of the initial layout:

[0020] Taking the initial sewage outlet as the center, sewage outlets of the same specifications are added one by one in the circumferential direction, and all sewage outlets in the circumferential direction are kept equally spaced. After each layout adjustment, steps S2.1 to S2.6 are repeated to perform Fluent simulation on the new layout, and whether the new layout reaches the set optimization goal is determined based on the simulation results, until the optimization is completed after the sewage outlet layout that can achieve the set optimization goal is found.

[0021] Furthermore, in step S1, the sewage discharge cycle is 40 to 60 seconds.

[0022] Furthermore, the three-dimensional modeling software used in step S2.1 is three-dimensional CAD software.

[0023] Furthermore, in step S2.2, the structured grid division method is: using a tetrahedral or hexahedral grid division method, performing grid encryption setting at the water inlet and sewage outlet, performing sparse grid division on other areas, and performing grid independence verification.

[0024] Furthermore, in step S2.3, the solver type is a pressure-based solver or a density-based solver.

[0025] Furthermore, in step S2.4, the turbulence model is a k-ε model or a k-ω model; the boundary conditions include the flow velocity, pressure and flow rate of the water inlet, the flow velocity, pressure and flow rate of the sewage outlet, and the pollutant concentration and sewage discharge method in the breeding pond, and the sewage discharge method is continuous sewage discharge or intermittent sewage discharge; the physical properties of the fluid domain include density and viscosity.

[0026] Further, in step S4, the distance between the initial sewage outlet and the sewage outlet in the circumferential direction is D, the diameter of the sewage outlet is d, and d≤D≤2d is satisfied.

[0027] Furthermore, the radius r of the sewage outlet satisfies 5cm≤r≤10cm.

[0028] The optimization principle of the sewage outlet layout of the present invention is: an iterative design strategy guided by Fluent fluid mechanics simulation technology is aimed at achieving the goal of efficiently purifying the water body of the aquaculture pond. Specifically, the method starts with a basic layout of a central sewage outlet, and then gradually adds sewage outlets in the circumferential direction according to the pollutant volume fraction change curve. After each step of adjustment, the Fluent simulation software is used to verify the optimization effect until the optimization goal of reducing the volume fraction of pollutants in the aquaculture pond to below 0.01% within the specified sewage discharge time is achieved. When the central sewage outlet is sucked, a low-pressure area will be formed around it, prompting the water body to flow toward the center. The setting of the circumferential sewage outlet can further guide the water flow, so that the water body forms a circular flow along the circumferential direction while flowing toward the center. This layout can form a more complex fluid dynamics effect. The central sewage outlet is the main outlet, and the circumferential sewage outlet is auxiliary, which can act on the water body together to form vortices and circulating flows, thereby enhancing the mixing and flow inside the water body, helping the mixing and diffusion of pollutants and water bodies, accelerating the purification process, improving the sewage discharge efficiency, and reducing the impact on the environment. At the same time, through the gradual optimization guided by precise simulation analysis, unnecessary sewage outlets are avoided, thus minimizing the construction cost and subsequent maintenance cost while ensuring the purification effect. This innovative solution undoubtedly provides an advanced solution that is both economical and practical for the sustainable development of the aquaculture industry.

[0029] The beneficial effects of the present invention are as follows:

[0030] 1. Through precise fluid dynamics simulation and layout optimization, the present invention can significantly improve the discharge speed and efficiency of pollutants, ensure that the breeding pond reaches an extremely low pollution level in a short time, which is conducive to maintaining a good breeding environment, reducing the risk of disease transmission, and improving the growth quality and yield of breeding organisms.

[0031] 2. Through sophisticated simulation analysis and intelligent iterative design, the present invention can achieve the set purification target with the least number of sewage outlets, which not only directly reduces the resource consumption of construction and maintenance, but also fully considers the stability and safety of the pool structure, avoiding the structural stress concentration, increased leakage risk and overall structural instability caused by adding too many sewage outlets. In addition, by optimizing the layout of sewage outlets, the present invention effectively controls the water exchange rate, prevents the drastic fluctuations of key water quality parameters such as water temperature and dissolved oxygen level caused by too fast water circulation, thereby creating a more stable and suitable growth environment for cultured organisms and avoiding the adverse effects of environmental mutations on the health and growth potential of organisms.

[0032] 3. The present invention takes the initial sewage outlet as the center of the circle and evenly arranges n sewage outlets of the same specifications in the circumferential direction, so as to achieve synergistic effect between water flows, form an effective vortex mixing mechanism, accelerate the mixing and diffusion process of pollutants and water bodies, and enable pollutants to be diluted and removed more quickly, thereby shortening the time of the entire sewage discharge process.

[0033] 4. The present invention can flexibly adjust the number and layout of sewage outlets according to the specific conditions of different breeding ponds (such as size, shape, water flow characteristics, etc.), has high adaptability and scalability, and is suitable for breeding facilities of various sizes and types.

[0034] 5. The present invention provides a scientific basis based on data and simulation to help managers make more accurate sewage system design decisions, avoid the blindness and limitations of traditional empirical layout, and improve the scientificity and rationality of the design. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is the optimal layout diagram of the sewage outlet at the bottom of the aquaculture pond described in the embodiment of the present invention.

[0036] Figure 2 This is a curve showing the change in volume fraction of pollutants in the aquaculture pond with discharge time under the optimal sewage outlet layout described in an embodiment of the present invention.

[0037] Figure 3 This is a simulation diagram of the vortex at the sewage outlet described in an embodiment of the present invention. DETAILED DESCRIPTION

[0038] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments, but the protection scope of the present invention is not limited thereto.

[0039] In order to verify the practical feasibility of the sewage outlet layout optimization method based on Fluent fluid simulation proposed in the present invention, this embodiment specially selects a representative breeding pond model as the research object. The breeding pond is a rectangular structure, covers an area of ​​400 square meters, and has an average water depth of 1.5 meters. It presents a moderate scale and provides a typical environment for the study of pollutant distribution and flow characteristics. Based on this specific model, we will first establish a benchmark sewage outlet layout in accordance with the guidance of the optimization strategy, and gradually adjust the location and number of sewage outlets according to the feedback of Fluent simulation analysis. The success of the optimization method is judged by comparing the changing trend of the volume fraction of pollutants in the breeding pond under different layouts over time, as well as the improvement effect after simulation optimization at each stage.

[0040] Specifically, the sewage outlet layout optimization method based on Fluent fluid simulation described in this embodiment includes the following steps:

[0041] S1: Set optimization goals:

[0042] Within a 50-second sewage discharge cycle, the volume fraction of pollutants in the aquaculture pond can be reduced to below 0.01% by arranging a minimum number of sewage outlets.

[0043] S2: Initial layout and simulation analysis:

[0044] A single sewage outlet is set in the center of the bottom of the aquaculture pond as the starting point for layout optimization. Fluent software is used for fluid dynamics simulation to simulate and obtain the curve of the volume fraction of pollutants changing with the sewage discharge time. The specific steps are as follows:

[0045] S2.1: Based on the actual size of the aquaculture pond, the actual location and size of the water inlet, the actual location and size of the sewage outlet, and the actual aquaculture area, a three-dimensional model of the aquaculture pond is established using three-dimensional CAD software, and the aquaculture area is defined as the fluid domain.

[0046] S2.2: Import the 3D model of the aquaculture pond into the Fluent software, divide the fluid domain into hexahedral structured grids, set mesh encryption at the water inlet and sewage outlet, divide other areas into sparse grids, and verify the grid independence.

[0047] S2.3: Select a solver and a solution method. In this embodiment, a pressure-based solver is selected, and a SIMPLE algorithm is selected as the solution method.

[0048] S2.4: Select a turbulence model, and set boundary conditions and physical properties of the fluid domain. In this embodiment, the turbulence model uses the k-ε model. The boundary conditions include the velocity, pressure and flow rate of the water inlet, the velocity, pressure and flow rate of the sewage outlet, and the pollutant concentration and sewage discharge method in the breeding pond. The sewage discharge method is continuous sewage discharge or intermittent sewage discharge. The physical properties of the fluid domain include density and viscosity, which are set to 998.2kg / m 3 and 1.002×10-3Pa·s.

[0049] S2.5: Initialize the boundary and set the calculation time step and iteration number of the Fluent solver to perform the calculation.

[0050] S2.6: Import the calculation results into CFD-post for visualization, and obtain the curve of the volume fraction of pollutants in the aquaculture pond changing with the discharge time.

[0051] S3: Evaluate the initial layout effect:

[0052] According to the simulation results, it is judged whether the initial sewage outlet layout has achieved the set optimization target. In this embodiment, after 50 seconds of sewage discharge under the initial sewage outlet layout, the volume fraction of pollutants in the breeding pond only dropped to 0.1%, which did not reach the set optimization target, and entered the next step of the optimization process.

[0053] S4: Multiple optimizations of the initial layout:

[0054] Taking the initial sewage outlet as the center, sewage outlets of the same specification are added one by one in the circumferential direction, and all sewage outlets in the circumferential direction are kept equally spaced. The distance between the initial sewage outlet and the sewage outlets in the circumferential direction is 24 cm, and the diameter of the sewage outlet is 14 cm. After each layout adjustment, steps S2.1 to S2.6 are repeated to perform Fluent simulation on the new layout, and whether the new layout reaches the set optimization goal is determined according to the simulation results. In this embodiment, the set optimization goal is first reached when the total number of sewage outlets is 7. Figure 1 This is the layout diagram of the sewage outlets at the bottom of the aquaculture pond when the total number of sewage outlets is 7. Figure 2 The curve of the volume fraction of pollutants in the aquaculture pond changing with the discharge time when the total number of sewage outlets is 7. It can be seen from the figure that when the total number of sewage outlets is 7, the volume fraction of pollutants in the aquaculture pond drops to 0.005% after 50s of sewage discharge, which is less than the set optimization target of 0.01%. Therefore, Figure 1 The outfall layout shown is the optimal solution.

[0055] In this embodiment, the initial sewage outlet is taken as the center of the circle, and six sewage outlets of the same specifications are evenly arranged in the circumferential direction, so as to achieve the synergistic effect between the water flows and form an effective vortex discharge mechanism. Figure 3 This is a simulation diagram of the eddy current at the sewage outlet. This layout not only accelerates the centralized discharge process of pollutants by utilizing the least number of sewage outlets, significantly shortening the retention time of pollutants in the aquaculture environment, but also improves the sewage discharge efficiency through optimized hydrodynamic design, while ensuring the minimum interference of the discharge process to the aquaculture organisms and the environment.

[0056] The embodiments are preferred implementations of the present invention, but the present invention is not limited to the above-mentioned implementations. Any obvious improvements, substitutions or modifications that can be made by those skilled in the art without departing from the essential content of the present invention belong to the protection scope of the present invention.

Claims

1. A method for optimizing sewage outlet layout based on Fluent fluid simulation, characterized in that: The following steps are involved: S1: Set optimization goals: The optimization goal of the layout of the sewage outlets of the aquaculture pond is to ensure that the volume fraction of pollutants in the aquaculture pond can be reduced to below 0.01% through the layout of the minimum number of sewage outlets within the set sewage discharge cycle; S2: Initial layout and simulation analysis: A single sewage outlet is set in the center of the bottom of the aquaculture pond as the starting point for layout optimization. Fluent software is used for fluid dynamics simulation to simulate and obtain the curve of the volume fraction of pollutants changing with the sewage discharge time. The specific steps are as follows: S2.1: Based on the actual size of the aquaculture pond, the actual location and size of the water inlet, the actual location and size of the sewage outlet, and the actual aquaculture area, a three-dimensional model of the aquaculture pond is established using a three-dimensional modeling software, and the aquaculture area is defined as a fluid domain; S2.2: Import the three-dimensional model of the aquaculture pond into the Fluent software and perform structured meshing on the fluid domain; S2.3: Select solver and solution method; S2.4: Select the turbulence model and set the boundary conditions and physical properties of the fluid domain; S2.5: Initialize the boundary and set the calculation time step and iteration number of the Fluent solver to perform the calculation; S2.6: Import the calculation results into CFD-post for visualization, and obtain the curve of the volume fraction of pollutants in the aquaculture pond changing with the discharge time; S3: Evaluate the initial layout effect: According to the simulation results, it is judged whether the initial sewage outlet layout meets the set optimization target. If it does, the initial sewage outlet layout is confirmed to be the optimal solution and the optimization process ends; if it does not, the next optimization process is entered; S4: Multiple optimizations of the initial layout: Taking the initial sewage outlet as the center, sewage outlets of the same specifications are added one by one in the circumferential direction, and all sewage outlets in the circumferential direction are kept equally spaced. After each layout adjustment, steps S2.1 to S2.6 are repeated to perform Fluent simulation on the new layout, and whether the new layout reaches the set optimization goal is determined based on the simulation results, until the optimization is completed after the sewage outlet layout that can achieve the set optimization goal is found.

2. The method for optimizing the layout of sewage outlets based on Fluent fluid simulation according to claim 1, characterized in that: In step S1, the sewage discharge cycle is 40 to 60 seconds.

3. The method for optimizing sewage outlet layout based on Fluent fluid simulation according to claim 1, characterized in that: The three-dimensional modeling software used in step S2.1 is three-dimensional CAD software.

4. The method for optimizing sewage outlet layout based on Fluent fluid simulation according to claim 1, characterized in that: In step S2.2, the structured grid division method is: using tetrahedral or hexahedral grid division method, performing grid encryption setting at the water inlet and sewage outlet, performing sparse grid division on other areas, and performing grid independence verification.

5. The method for optimizing sewage outlet layout based on Fluent fluid simulation according to claim 1, characterized in that: In step S2.3, the solver type is a pressure-based solver or a density-based solver.

6. The method for optimizing sewage outlet layout based on Fluent fluid simulation according to claim 1, characterized in that: In step S2.4, the turbulence model is a k-ε model or a k-ω model; the boundary conditions include the flow velocity, pressure and flow rate of the water inlet, the flow velocity, pressure and flow rate of the sewage outlet, and the pollutant concentration and sewage discharge method in the breeding pond, and the sewage discharge method is continuous sewage discharge or intermittent sewage discharge; the physical properties of the fluid domain include density and viscosity.

7. The method for optimizing sewage outlet layout based on Fluent fluid simulation according to claim 1, characterized in that: In step S4, the distance between the initial sewage outlet and the sewage outlet in the circumferential direction is D, the diameter of the sewage outlet is d, and d≤D≤2d is satisfied.

8. The method for optimizing sewage outlet layout based on Fluent fluid simulation according to claim 7 is characterized in that: The radius r of the sewage outlet satisfies 5cm≤r≤10cm.

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