ABOUT DARCY'S LAW

Darcy was a French Civil Engineer (or now a Freedom Engineer ?) from Ecole des Ponts et Chaussées. He developed his theory (1856) while working for the water supply of the City of Dijon.

At Darcy’s time, hydrogeology was still arguing about the Greek water cycle, from the sea to the continents. Father Paramelle’s famous book “The art of discovering springs” (1856, 1859), with no mention of Darcy’s work, was the best seller, not Darcy’s. Fourier (1768-1830), a French Professor and Academician, taught Darcy his law. Poiseuille’s (1844) and Ohm’s (1827) laws were also familiar to him. Darcy’s experiments for proving the linearity of flow versus head gradients was thus founded on earlier work. He knew about non-linear (turbulent) flow, on which he published in 1857, but he did not try to relate porous media to a series of tubes in laminar conditions. He was satisfied with the experimental evidence, and did not wish to relate it to an underlying equation of physics.

To me, his major mistake is to have extended linearity one step too far, assuming proportionality of flow with surface area, thus opening the door for irrelevant concepts such as REVs, and the problems of change of scale, etc, which cannot be understood nor resolved if spatial variability is ignored. He also ignored other forces (e.g. osmosis).

Politically, Darcy was born during a troubled period of France’s history, starting with the Revolution (1789), then Napoleon Bonaparte’s Consulat, Empire, the restored French Monarchy, the failed revolution of 1830, the 2nd Republic, and the 2nd Empire. He was a graduate form an engineering school, organised by Napoleon to support the empire’s wars, but also its economic development : roads, bridges, water supply…

Darcy’s science was problem-solving, developed for engineering purposes, contrary to Ohm’s and Fourier’s, who were more members of the “Century of Lights” where the object was the deciphering of Nature’s laws, not engineering. During Darcy’s time, France was imperialistic. Initially, the wars were meant to bring freedom to the people still subdued by barbaric kings. But soon imperialism was to become conquests and domination : the French colonies, a series of imperialistic wars, ending up with World War I and II. Darcy’s science was imperialistic, in a way, at the very least, I believe, inspired by imperialism.