Flow network-based heterogeneous aquifer dominant flow path identification method

An identification method and heterogeneous technology, applied in the field of hydraulics, can solve problems such as large amount of calculation, error, large time and storage space, achieve high accuracy and efficiency, conform to physical laws, and achieve simple effects

Active Publication Date: 2019-07-05
NANJING UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

This method is reliable, but the main problem is that the calculation is very large, requiring a lot of time and storage space, and the calculation of the next moment position based on the current position of the particle is easy to introduce accumulated errors
The MHR method uses an algorithm similar to navigation pathfinding to find the path with the least overall resistance, and has high computational efficiency, but it does not consider hydrodynamic conditions and boundary conditions, which may easily lead to search results that do not conform to hydrodynamic laws. Therefore, the reliability of this method still unsatisfactory

Method used

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  • Flow network-based heterogeneous aquifer dominant flow path identification method
  • Flow network-based heterogeneous aquifer dominant flow path identification method
  • Flow network-based heterogeneous aquifer dominant flow path identification method

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0056] Example 1: Homogeneous aquifer with two low-permeability walls

[0057] The research object is a homogeneous confined aquifer with two low-permeability walls, the regional average water flow is from left to right, and the permeability coefficient ratio of the main body and the low-permeability wall is K / K b =10 3 (Such as image 3 shown), porosity is a constant. Adopt SF method of the present invention, calculate differential streamline and each stream tube area A (as Figure 4As shown, the figure shows the spatial distribution of equal differential streamlines, that is, the difference between the flow functions of adjacent streamlines is equal; the A value of the stream pipe is shown on the right, and the minimum A value is marked by a hollow circle, which is close to the symmetrical center of the aquifer axis), the flow tube corresponding to the smallest A is the dominant flow path. The obtained SF path is a streamline straight through the wall gap, which is con...

Embodiment 2

[0058] Example 2: A homogeneous aquifer containing multiple low-permeability walls;

[0059] Similar to the previous example, consider the case of low-permeability walls in a mean confined aquifer, the difference is that there are more low-permeability walls and their distribution is more complex (such as Figure 6 shown). Similarly, use the three methods of PT, MHR, and SF to find the dominant flow path, and compare it with the particle front and the first arrival point in the PT method (see Figure 7 ). The results show that the SF path (dotted line) of the present invention is almost completely consistent with the PT path (solid line); the MHR path has a significant difference, which is reflected as the shortest path to avoid low-permeability walls. Figure 8 It further shows the streamline distribution of the water flow field in this example and the A value of each flow tube, Figure 8 The A-values ​​for each flowtube are shown on the right (minimum A-values ​​are marke...

Embodiment 3

[0060] Example 3: Predominant flow in multi-Gaussian logarithmic permeability coefficient field

[0061] Considering a two-dimensional rectangular confined aquifer, the logarithmic permeability coefficient lnK satisfies the multi-Gaussian distribution assumption, the mean value of lnK is 0, the variance is 1.5, and the correlation length is 50m. Generate a random lnK sample with a sequential Gaussian simulation (eg Figure 9 shown). Considering the regional water flow from left to right as well, see Figure 10 . The results show that the SF path is basically consistent with the PT path, both pointing to the first arrival of the particles; the MHR path swings violently, which is significantly different from the PT path, passing through multiple particle fronts, and the end point on the right is also inconsistent with the first arrival path. It shows that the SF path in this example is much closer to the real dominant flow path than the MHR path. Figure 11 The relationship ...

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Abstract

The invention discloses a flow network-based heterogeneous aquifer dominant flow path identification method. The method comprises the following steps of firstly, establishing a quantitative relation between the area or volume of a flow pipe and the water flow movement time; applying an existing groundwater flow simulation program to the flow function calculation in the heterogeneous medium; and calculating the area or volume of the flow pipe, so that the moving path with the shortest time can be efficiently and accurately identified. Compared with the existing particle tracking method and thegraph theory technology, the method provided by the invention is higher in efficiency and better in accuracy.

Description

technical field [0001] The invention belongs to the technical field of hydraulics, and specifically refers to a method for identifying a dominant flow path of a heterogeneous aquifer based on a flow network. Background technique [0002] At present, more and more attention has been paid to the problem of groundwater pollution; one of the difficulties in groundwater solute transport lies in the existence of dominant flow in the groundwater flow field, that is, the dominant channel that occupies a small part of the aquifer and has strong water conductivity can often transport Large volumes of water flow and solutes can even significantly alter aquifer behavior. The heterogeneity of the aquifer, which is ubiquitous in nature, is the main factor leading to the heterogeneity and dominant flow of the groundwater flow field. Identifying the dominant flow path in groundwater flow field based on aquifer heterogeneity is an important part of groundwater migration simulation and water...

Claims

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Application Information

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IPC IPC(8): G06F17/15
CPCG06F17/15
Inventor 南统超吴吉春王远坤
Owner NANJING UNIV
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