Numerical methods and image analysis to predict the transport properties of porous media.

摘要

Structural characteristics have a significant effect on the flow of fluids through a porous media such as paper. In this work, a technique has been developed to characterize conventional structural parameters such as porosity, specific surface area and tortuosity in fibrous porous media. X-ray microtomography is used to obtain the images of the entire 3D structure of the paper sample. The technique is non-destructive and does not cause any changes to the structure during the imaging process. Structural parameters are then calculated by analyzing the images.; Handsheets of varying structures were prepared in the laboratory. Varying fiber structures were obtained by mechanical treatment of the pulp fibers. Porosity and specific surface area values of these samples were obtained from an analysis of x-ray microtomographic images and compared with results from conventional mercury intrusion porosimetry.; The liquid permeability values of the paper samples were calculated using the Kozeny-Carman theory and the results were compared with Lattice-Boltzmann simulations. Vapor diffusivity within the paper samples was investigated using random walk simulations of the trajectories of molecules diffusing through the porous paper structure. Simulation results were compared with the values obtained from experiments.