A porous medium or a porous material is a solid (often called frame or matrix) permeated by an interconnected network of pores (voids) filled with a fluid (liquid or gas). Usually both the solid matrix and the pore network (also known as the pore space) are assumed to be continuous, so as to form two interpenetrating continua such as in a sponge. Many natural substances such as rocks, soils, biological tissues (e.g. bones), and man made materials such as cements, foams and ceramics can be considered as porous media. A poroelastic medium is characterised by its porosity, permeability as well as the properties of its constituents (solid matrix and fluid).
The concept of porous media is used in many areas of applied science and engineering: mechanics (acoustics, geomechanics, soil mechanics, rock mechanics), engineering (petroleum engineering, construction engineering), geosciences (hydrogeology, petroleum geology, geophysics), biology and biophysics, material science, etc. Fluid flow through porous media is a subject of most common interest and has emerged a separate field of study. The study of more general behaviour of porous media involving deformation of the solid frame is called poromechanics.
——WIKIPEDIA
楼主留言：
这个定义说孔隙是相互连通的，而且是充满流体的，其实是不必要的，^_^
