390 / 2024-03-28 21:46:43

Advanced modelling of transport in porous and fractured

pore space; structure-preserving analysis; hydraulic conductivity

3、深地工程与能源利用 > 1、深部岩土力学基础理论

Abstract: A flexible approach to modelling porous and fractured media is presented, together with a unique method for analysis of transport in such media. The approach uses a polyhedral tessellation of a material domain with allowance for pores and fractures to be associated with different elements – polyhedrons, faces, and edges. This is a major advance from the known pore networks, as pore spaces of arbitrary complexity can be faithfully represented. The analysis of transport uses novel structure-preserving operators that provide exact numerical solutions over exponentially long times, which is not the case for domain discretization numerical methods, such as finite elements or finite volumes. The method is tested using X-ray computed tomography (XCT) images of bentonite. The pore space is reconstructed and analysed by Avizo to obtain the shape, size distributions and volume fraction of pores, the surface area and tortuosity of the pore space, and to calculate its hydraulic conductivity using fluid mechanics. The pore characteristics are used to calculate the conductivity according to a modified Kozeny-Carman equation for comparison with numerical data. The model is constructed based on XCT images with pores having platelet shapes, situated between grains, and conducting fluid as illustrated in the figure. The simulation results are in excellent agreement with the fluid mechanics and Kozeny-Carman predictions, confirming the model predictive capability. The key benefits are lower computational cost with superior accuracy and inherent potential for investigating the effect of evolving pore space on transport properties.