Henry Darcy

From HydroWiki

Life and Work

Henry Philibert Gasparad Darcy was born in 1803 in Dijon, France. His mother, widowed in 1817 stressed the importance of education and sent Henry to the Dijon Polytechnique and later L’Ecole des Ponts et Chaussets, where he graduated with a degree in Civil Engineering in 1826. Darcy soon found work in Bureau of Bridges and Highways where he quickly excelled.

Henry performed a wide variety of tasks under the Bureau of Bridges and Highways including the supervision of the construction of two bridges and a railway tunnel. However, he soon began to focus on water and its flow through various mediums, work in which he would become famous. In the 1830’s Darcy began to design a system for the distribution of water in Dijon, and he was awarded the contract in 1838. His system consisted of two reservoirs, a 5 ½ km aqueduct, 11 km of pipeline, and many fountains placed throughout the city. Before his work, Dijon relied on wells of poor quality water, and the Suzon, a small stream that served as the main sewer for the town. After the completion of the project Dijon has a water system that was rivaled in design only by that of Rome, and was constructed 20 years ahead of the system in Paris. For his work Darcy received the Legion of Honor and was entitled to the consultant’s fees of 55,000 francs. He turned down the fees, only accepting a lifetime service of free water at his home.

Darcy did not become known for his most famous contribution until his 1856 release of his report “Les Fontaines Publiques de la Ville de Dijon” where the law now named after him appeared. Darcy’s Law is empirical, based on his measurements of water flow through sand. A cylindrical column of a height of 2.5 m and a width of 0.35m was filled with sand and attached were two manometers, one affixed at the top and the other the bottom. The experiment consisted of running water through the column at fixed rate and measuring the output. He determined that in identical sands the discharge is directly proportional to the head and inversely proportional to the thickness of the column. Modern use of the equation often includes determining the velocity of the discharge, and determining the hydraulic conductivity through the difference of the head between the top and bottom, divided by the length of the profile.

Darcy’s Law is expressed in many forms, all being derived from:

The equation shows the total discharge Q is equal to the permeability κ of the medium times the cross-sectional area A of flow, with pressure drop (Pb − Pa), all divided by the dynamic viscosity μ, and length L. The negative represents the flow from high to low pressure.

The delay of Darcy’s work could possibly be accounted to the fact that he was banished from Dijon in 1848 due to the overthrowing of King Louis-Philippe and the establishment of the Second Republic. However, the Second Empire of Napoleon III brought Darcy back to his home city. But by this time he was in declining health and part of his research was performed in the hospital. Darcy would receive recognition for his work, being elected to the Academie des Sciences in 1857. However his vacancy was short and he died on January 2, 1858. He was buried in Dijon where a monument was built for him, and the Chateau d’Eau, where the waters of the spring of Rosoir enter Dijon, was named la’ place Darcy.

Links

http://biosystems.okstate.edu/darcy/

References

Darcy's law. (2008, January 13). In Wikipedia, The Free Encyclopedia. Retrieved 19:56, January 22, 2008, from http://en.wikipedia.org/w/index.php?title=Darcy%27s_law&oldid=184094354

Freeze, R. Allen. "Henry Darcy and the Fountains of Dijon." Ground Water 32, no.1(1994): 23–30.

Philip, J. R. "Desperately Seeking Darcy in Dijon." Soil Science Society of America Journal 59, no. 2 (1995): 319–324.