Method for representing time-space scale association of solute transport in porous medium

Abstract

The invention discloses a method for representing time-space scale association of solute transport in a porous medium. The method comprises the steps of selecting a solute transport process in the specific porous medium as a research object, determining a test condition, and obtaining test data of a solute breakthrough curve; building a time-space fractal derivative convection dispersion model, and deriving an analytic solution of the time-space fractal derivative convection dispersion model; in combination with the test data of the solute breakthrough curve, calculating parameters of the time-space fractal derivative convection dispersion model, quantizing the solute breakthrough curve by adopting the analytic solution of the model, and analyzing early arrival and trailing features of thebreakthrough curve; and according to values of the model parameters, analyzing an association degree between the model parameters and a time or space scale, and giving a quantitative relationship between the model parameters and the time or space scale. The smaller the orders of a time fractal derivative and a space fractal derivative are, the higher the time-space association degree is, and themore remarkable the early arrival and trailing features of the breakthrough curve is. The method can be used for groundwater and soil pollution prediction, assessment, remediation and the like, and isconvenient for use in engineering.

Description

technical field [0001] The invention relates to an environmental fluid technology method, in particular to a method for characterizing the time-space scale correlation of solute migration in a porous medium. Background technique [0002] The collection and transportation of oil and gas, the solidification and storage of carbon dioxide, the deep burial storage of nuclear waste, the site selection of landfills, and seawater intrusion and other engineering problems all involve the common problem of solute migration in porous media. A large number of indoor and field experiments have shown that the solute transport process in porous media usually exhibits time-scale correlation characteristics, that is, its diffusion coefficient or flow rate is no longer a constant, but a linear or nonlinear function of time or space. This type of process is called is a non-Fick, anomalous or non-Gaussian transport process. Therefore, exploring and quantifying the laws of the time-space scale c...

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Problems solved by technology

The fractional derivative convection-dispersion model is a special case of the continuous-time random walk model. Its main problem is the high computational cost. Although the model parameters have clear meanings, they cannot establish a direct relationship with the geometric characteristics of porous media.

[0004] The prior art also involves the problem of solute transport in porous media. For example, the random walk particle tracking method is used to simulate the solute transport in single-crack media to obtain the distribution of solute. This method is not combined with the actual solute transport problem; Yes, combined with the properties of the Markov chain, the random walk model is used to simulate the solute migration process in groundwater, but the time-space scale correlation characteristics of the solute migration process are not considered; in addition, there is also a time-fractal derivative model based on the numerical simulation of the anomalous diffusion of chloride ions , this method does not consider the spatial scale correlation; based on the problems of the above method, a new method for characterizing the temporal and spatial scale correlation of solute transport in porous media is needed to solve the above problems

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