Fitting function and correlation.

The cell structure of three different densities of bituminous coal molecules was modeled and optimized by using Material Studio (MS) to reveal the mathematical relationship between the porosity and permeability of bituminous coal. The internal surface area was analyzed using the Connolly Surface module, and the specific surface area of the molecules was obtained by mass conversion; the grey processing method was used to evaluate the cell structure porosity, and the pore-permeability constitutive relationship of bituminous coal molecules was established by drawing on the Kozeny-Carman (KC) equation. The results show that the maximum value of 0.29 appears near the pore size of 2.01 Å; Porosity is the main factor affecting its permeability, and the permeability decreases with increasing porosity. The relationship between porosity and permeability was obtained by regression analysis as follows: K = 161 2.1/(1 + 12 2.1). This study provides a new method for the calculation of permeability of porous media.本研究采用Materials Studio（MS）软件对三种不同密度的烟煤分子晶胞结构进行建模与优化，以揭示烟煤孔隙率与渗透率之间的数学关联。通过Connolly Surface模块分析其内表面积，并经质量换算得到分子的比表面积；采用灰色处理法对晶胞结构孔隙率进行评价，并借鉴Kozeny-Carman（KC）方程构建了烟煤分子的孔-渗透率本构关系。结果表明，在孔径2.01 Å附近出现0.29的最大值；孔隙率是影响其渗透率的主导因素，渗透率随孔隙率增大而降低。通过回归分析得到孔隙率与渗透率的关系式如下：K = 161 2.1/(1 + 12 2.1)。本研究为多孔介质渗透率的计算提供了一种新方法。