Porous Media Fundamentals

A porous medium consists of a solid structure with void spaces that are in general complicated and distributed throughout the structure. The void spaces can be interconnected or not. The pores are identifiable regions that serve as elements for the void space. The traditional view of porous media was inspired by porous structures found in nature, for example, packed sand saturated with water that seeps through the pores. Natural porous structures have random features, such as irregular pore shapes and sizes, and irregular connections between the pores. Today we are seeing a growing number of technologies that rely on flows through complex and small-scale passages. The structures formed by such passages can be viewed as designed porous media—structures where the pore shapes, sizes, and connections are special and purposeful, not irregular or random. Designed porous media are components of larger systems and installations that meet global objectives and perform functions under constraints.