Ludwig Prandtl (1875-1953)

Ludwig Prandtl was born in Freising, Germany, in 1875. He studied mechanical engineering in Munich. For his doctoral thesis he worked on a problem on elasticity under August F ppl, who himself did pioneering work in bringing together applied and theoretical mechanics. Later, Prandtl became F ppl's son-in-law, following the good German academic tradition in those days. In 1901, he became professor of mechanics at the University of Hanover, where he continued his earlier efforts to provide a sound theoretical basis for fluid mechanics. The famous mathematician Felix Klein, who stressed the use of mathematics in engineering education, became interested in Prandtl and enticed him to come to the University of G ttingen. Prandtl was a great admirer of Klein and kept a large portrait of him in his office. He served as professor of applied mechanics at G ttingen from 1904 to 1953; the quiet university town of G ttingen became an international center of aerodynamic research.

In 1904, Prandtl conceived the idea of a boundary layer, which adjoins the surface of a body moving through a fluid, and is perhaps the greatest single discovery in the history of fluid mechanics. He showed that frictional effects in a slightly viscous fluid are confined to a thin layer near the surface of the body; the rest of the flow can be considered inviscid. The idea led to a rational way of simplifying the equations of motion in the different regions of the flow field. Since then the boundary layer technique has been...