Optimized Design of Hydrodynamic Enhanced Water Pump System in Landscape Water System

: In view of the small flow rate, slow velocity and closed circulation of landscape water, water quality deterioration is easy to occur, the hydrodynamic driving method is selected to treat landscape water. Based on hydrodynamic model, three cases were studied for optimal designing. Scheme 1 and 2 are boundary water inlet and outlet, scheme 3 is internal point water inlet and outlet. Analyze the flow rate of the three schemes, and choose the best scheme more intuitively. In Scheme 1, about 30% of the simulated flow area in the south region has a flow velocity exceeding 0.3m/s. About 50% of the flow rate in the northern region obtained by the simulation of Scheme 3 is greater than 0.30 m/s. By comprehensive comparison, it can be seen that the north region selection scheme 3 and the south region selection scheme 1 have the best effect on the overall flow velocity improvement and can be used as the best scheme.

is poor, and the water flow rate is low, which is prone to the problem of water quality deterioration.The above problems are solved by designing the water system hydrodynamic enhancement pump system to improve the flow rate.

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Where x and y are the spatial coordinates, t is the time, h is the water depth, ξ is the free water level, p, q are the flow density in x and y directions, c is the Chezy resistance coefficient, g is the gravity acceleration, f (V) is the wind friction factor, V and Vx, VyIs the wind speed and the wind speed component in the x and y direction, Ω, is the Coriol coefficient [10] .

Establishment of the Moon Bay model
The water area of Moon Bay is divided into two independent waters by north ditch.In order to facilitate calculation and choose the best design scheme, the two areas of Moon Bay are analyzed and calculated separately, as shown in Figure 1.When establishing the model, the flow rate provided by the pump is converted into the flow rate of boundary conditions (Table 1, Table 2, Table 3, Table 4, Table 5, and Table 6) to facilitate analysis and calculation.Firstly, the boundary model is established, as shown in Figure 6 and Figure 7.

Determine the simulation scheme
We observe the topographic distribution of Moon Bay, compare the position and number of inlet and outlet respectively, and finally determine three sets of distribution schemes [11] , as shown in Figure 8-10 and Table 1-    water penetration 1 1020 120

Results and Discussion
The simulation results of the south side hydrodynamic model are shown in the figure below [12]  Compared with Figure 11 and Figure 13, the flow field indicates that the flow field has not reached the stable state; for the comparison between Figure 12 and Figure 13, the flow field is basically consistent and the flow field is stable, so the flow field characteristics are analyzed in combination with the simulation results of the fifth hour.

Simulation results of scheme hydrodynamic model
The maximum flow rate in the north area of Scheme 1 is 0.44m / s, the flow rate exceeding 0.3m / s is less than 10%, and the flow field is relatively small overall.The water flow basically follows the flow from south to north direction.Flow velocity is lower at broad east-west distances and relatively high at narrower locations [13] 0, as shown in Figure 14   The maximum flow rate in the south area is 0.48 m/s, and the flow rate exceeding 0.3m / s is less than 30%.The water flow basically follows the flow direction from north to south.Flow velocity is lower at wide east-west distances and higher at narrow east-west distances.

Simulation results of Scheme 2 hydrodynamic model
The maximum flow rate in the north area of scheme 2 is 0.375m / s, the flow rate exceeding 0.3m / s is less than 10%, and the flow field is relatively small overall.The water flow basically follows the flow from south to north direction.Flow velocity is lower at broad east-west distances and relatively high at narrower locations, as shown in Figure 16   The maximum velocity in the south area of Scheme 2 is 0.44 m/s, and the velocity exceeding 0.3m/s is less than 20%.The water flow basically follows the flow from south to north direction.Flow velocity is lower at wide east-west distances and higher at narrow east-west distances.

Scheme three hydrodynamic model simulation results
The maximum flow rate of the north area of scheme 3 is 1.50m / s, about 50% of the flow rate exceeds 0.3m / s, and about 70% of the area flow rate exceeds 0.1m / s.Compared with scheme 1 and scheme 2, the overall effect is also significantly improved.The water flow basically follows the flow from south to north direction.Flow velocity is lower at broad east-west distances and relatively high at narrower locations [14] , as shown in Figure 18   The maximum flow rate in the south area of Scheme 3 is 1.80 m/s, and the flow rate exceeding 0.3m / s is less than 20%.The flow rate of the flow field is small, and a small area of the water flow is promoted, still does not participate in the circulation.If the maximum flow velocity exceeds 0.375 m/s and the area is less than 10%, the maximum flow velocity exceeds 0.44 m/s and the flow velocity exceeds 0.3m/s is less than 20% [15] .
The maximum flow rate on the north side of the scheme 3 exceeds 1.50 m/s; the area is about 50%, and the water flow rate is over 0.1 m/s; the maximum flow rate in the south side exceeds 1.80m/s, and the water flow rate in most areas is lower than 0.15m/s.
By comprehensively comparing the flow rate of the three schemes, the scheme 1 in the south area and the north area adopt scheme 3 as the optimal scheme.

Conclusion
This paper designs the scheme of MIKE and predicts the flow velocity.Based on the model operation results of the three schemes, the following conclusions are obtained: The hydrodynamic model is established by MIKE 21 to predict the flow rate under different schemes.The maximum flow rate in the south area exceeds 0.48 m/s and the flow rate exceeds 0.3 m/s is about 30%; that the maximum flow rate in the north area exceeds 1.50m/s compared with Scheme 1 and Scheme 2, about 50% of the flow rate is more than 0.30 m/s, exceeding 0.3m/s can maintain the virtuous cycle of urban water ecosystem, and the overall effect is significantly improved compared with Scheme 1 and Scheme 2, and about 70% of the regional water flow rate exceeds 0.1m/s.
By comprehensive comparison, it can be seen that the selection scheme of the north area and the south area have the best effect on improving the overall flow rate and can be used as the best scheme.

Figure 1 :
Figure 1: Topographic map of Moon Bay Turn the north and south topographic maps into the CAD topographic map and then select the boundary points and internal points.The boundary data and elevation data were extracted, the xyz files were converted separately, imported into MIKE zero, and the grid was drawn, as shown in Figure 2 and 3.

Figure 3 :
Figure 3: Topographic grid section (South area) Model running time setting: the selected model running time starts 00:00:00 on January 1, 2023 and runs until 5:00:00 on January 1, 2023.The total time was 5 hours with time steps of 36s and 500 steps.The imported topographic data is shown in the Figure 4 and 5 below.

Figure 4 :
Figure 4: North-side area topographic data

Figure 5 :
Figure 5: Topographical data of the south side area

Figure 6 :
Figure 6: Distribution diagram of boundary setting (north side area)

Figure 11 :Figure 12 :Figure 13 :
Figure 11: Schematic diagram of water flow rate distribution at the second hour and 15.

Figure 14 :
Figure 14: Schematic distribution of flow rate in the fifth hour

Figure 15 :
Figure 15: Distribution of water flow rate at the fifth hour and 17.

Figure 16 :
Figure 16: Schematic diagram of water flow rate distribution at the fifth hour

Figure 17 :
Figure 17: Distribution of water flow rate at the fifth hour and 19.

Figure 18 :
Figure 18: Distribution of water flow rate at the fifth hour

Figure 19 :
Figure 19: The distribution of water flow rate at the fifth hour 3.1.4The best scheme determined by the hydrodynamic model Where the maximum flow velocity exceeds 0.44 m/s and less than 10% exceeds 0.3 m/s; the maximum flow velocity exceeds 0.48 m/s and the flow velocity exceeds 0.3 m/s is less than 30%.If the maximum flow velocity exceeds 0.375 m/s and the area is less than 10%, the maximum flow velocity exceeds 0.44 m/s and the flow velocity exceeds 0.3m/s is less than 20%[15] .The maximum flow rate on the north side of the scheme 3 exceeds 1.50 m/s; the area is about 50%, and the water flow rate is over 0.1 m/s; the maximum flow rate in the south side exceeds 1.80m/s, and the water flow rate in most areas is lower than 0.15m/s.By comprehensively comparing the flow rate of the three schemes, the scheme 1 in the south area and the north area adopt scheme 3 as the optimal scheme.

Table 1 :
Scheme setting of the northern area boundary

Table 2 :
Scheme 1 The boundary scheme setting of the south area

Table 3 :
Scheme setting on the northern regional boundary side of Scheme II

Table 4 :
Scheme 2 Border scheme setting of the south area

Table 5 :
Scheme setting of the three region boundary

Table 6 :
Setting of the south area boundary scheme