基于机器学习的指定渗透率随机多孔介质生成方法

    Generation of random porous media with specified permeability based on machine learning

    • 摘要: 土体作为多相多孔介质,其孔隙结构具有明显的随机性,采用已有方法生成的多孔介质的渗透率通常是随机的,因此现阶段生成具有指定渗透率的随机多孔介质仍然是一个难题。为此,提出了一种基于机器学习,且能高效生成具有指定孔隙率、孔隙特征尺寸和渗透率的随机多孔介质的方法。采用截断高斯随机场法重建了一系列随机多孔介质的数值模型,其孔隙结构可由孔隙率和孔隙特征尺寸两个建模参数定量控制;利用格子Boltzmann方法计算了生成随机多孔介质的渗透率;基于3000组孔隙结构与渗透率关系的数据,拟合了预测随机多孔介质渗透率上下界的经验公式,并训练出了能从多孔介质的图像准确预测其渗透率的卷积神经网络。结果表明:预测值与测试集的决定系数、平均绝对误差和均方根误差分别为0.992 2,0.048 0,0.113 0。预测时间约为0.08 s,单个模型生成时间约1 min。当前方法可高效、准确地生成随机多孔介质,为其定制化模拟提供了一种有力手段。

       

      Abstract: Soil, as a porous medium, exhibits significant randomness in pore structure.Existing methods for generating porous media typically yield permeability values that are random, making it challenging to produce random porous media with a specified permeability.To address this issue, this paper proposes a machine learning-based approach capable of efficiently generating random porous media with a target porosity, characteristic pore size, and permeability.A series of numerical models of random porous media were constructed using the truncated Gaussian random field method, where pore structures are quantitatively controlled by two modeling parameters: porosity and characteristic pore size.The permeability of the generated media was computed using the lattice Boltzmann method.Based on 3, 000 datasets describing the relationship between pore structure and permeability, empirical formulas were fitted to predict the upper and lower bounds of permeability of the random porous media.Additionally, a convolutional neural network was trained to accurately predict permeability directly from images of porous media.Results show that the coefficient of determination, mean absolute error, and root mean square error between the predicted and test values are 0.992 2, 0.048 0, and 0.113 0, respectively.Prediction time is approximately 0.08 seconds, and the generation time for a single model is about 1 minute.The proposed method enables efficient and accurate generation of random porous media, providing a powerful tool for seepage simulation.

       

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