THEORY OF POROUS-MEDIA - PAST AND PRESENT

Porous solids filled with liquid or gas play an important role in engi neering, e.g., in material science, petroleum industry, chemical engin eering, and soil mechanics as well as in biomechanics. Although porous media are of considerable practical significance the description of t heir mechanical and thermodynamical behavior has been unsatisfactory f or a long time. The theory to describe the complex thermodynamical beh avior of such saturated porous solids has come to certain well-founded conclusions only recently. It is the goal of this paper to show the h istorical development of the porous media theory, which already starte d in the eighteenth century, formed in some areas by polemic disputes and tragic events in the lifes of the scientists involved. Furthermore , the current state of the research into this subject is discussed; wh ereby the state of the development of the material independent basic e quations and the constitutive theory is illustrated. For a certain cla ss of models general theorems, such as minimum and maximum problems, a re derived and the uniqueness of solutions of boundary value problems is proved.