Numerical Simulation Of Gas Transport Properties In Fractal Porous Media With Rough Surfaces

Porous media widely exist in the fields of nature and engineering,and their internal transport mechanism has become one of the hot topics of research at home and abroad.Due to the complexity and randomness of the internal pore structure of porous media,the surface topography of internal pores or channels is often ignored when exploring gas transport processes.Therefore,based on fractal geometry theory and Monte Carlo method,this paper focuses on simulating the detailed process of gas transport in porous media with rough topography,and analyzes the detailed effects of porous media structural parameters,especially the pore surface roughness on gas transport characteristics.mechanism.The specific research contents are as follows:（1）Construction of the porous medium model: comprehensively analyze the statistical self-similar characteristics of the internal pore structure and pore surface structure of the porous medium,and use the fractal geometry theory to construct the pore distribution model and rough surface model of the porous medium,so as to establish a porous medium with a rough surface.Media Theory Models.（2）To study the gas diffusion process in porous media,through the analysis of the internal gas diffusion process of porous media,based on fractal theory and Fick’s law,the effective gas diffusion coefficient equation in the porous media model with rough surface is deduced.（3）Research on the gas flow process in porous media.For different Knudsen numbers,there are different flow modes inside the porous media.Based on fractal theory,Fick’s law and Hagen-Poiseuille equation,the gas flow rate under this flow regime and Darcy’s law are combined to derive the permeability equation in porous media with rough surfaces.（4）The Monte Carlo method is used to numerically simulate the gas transport process inside the porous medium,and compared with the experimental data to verify the accuracy of the new theory,and the results are related to roughness,porosity,tortuosity,Relationship between maximum and minimum pore diameter ratio,fractal dimension and rough surface area.and explain the reasons for these relationships.The research results show that when studying the gas transport process on rough surfaces,the fractal-Monte Carlo simulation can make the results closer to the actual results,and the porosity has a positive correlation with the effective gas diffusion coefficient and permeability;at the same time,the effective gas diffusion coefficient and permeability are also related to structural parameters such as the roughness of porous media,the ratio of maximum and minimum pore diameters,and the fractal dimension of tortuosity.This study can more specifically reflect the gas transport process in the microstructure of the rough surface of the porous medium,which has certain guiding significance for the gas transport in the porous medium with the rough surface.