Development of porous media theories — A brief historical review

For a complete understanding of the complex theories in continuum mechanics, e.g., porous media theories, an extensive investigation of their historical development is helpful. Indeed, it was first with activities in this field that fundamental effects in saturated porous solids, e.g., uplift, friction, capillarity, and the effect of effective stresses, could be clarified.The theory of porous media was pioneered by Reinhard Woltman in 1794 when he introduced the concept of volume fractions. Last century, important contributions were published by Adolf Fick, Henry Darcy, and Josef Stefan.In the twentieth century, the scientific discussion on porous media theories was started by Paul Fillunger in 1913 in a paper about the uplift problem in saturated rigid porous solids. In subsequent papers, he investigated the effects of friction and capillarity and discovered the effect of effective stresses. In 1923 Karl von Terzaghi, founder of modern soil mechanics, started his investigations on saturated deformable porous solids within the framework of the calculation of the permeability coefficient of clay. For the derivation of his famous differential equation, he formulated a linear constitutive relation between the increments of the porosity and the effective stresses. In 1936, Paul Fillunger founded the concept of the modern theory of liquid-saturated porous solids. However, his findings are almost completely forgotten.Today, two important directions of the porous media theory are commonly acknowledged. The first one is based on investigations by Maurice Biot, the second one proceeds from the mixture theory, extended by the concept of volume fractions.