Ludiwg Prandtl was born in Friesing , Upper Bavaria on February 4th 1875. Why is he important? Here are just a few of his contributions to the field of fluid mechanics:

• defined the concept of the boundary layer and explained its importance to drag, streamlining, and flow separation,
• identified wing-tip effects and their degradation of performance,
• developed the first theories of supersonic shock waves and Prandtl-Meyer expansion fans,
• developed the first modern, closed-loop wind tunnel,
• designed the supersonic nozzle used in all modern supersonic wind tunnels, and
• came up with the Prandtl-Glauert correction for predicting compressibility corrections for airfoil performance prediction.

You might know a few of the 85 doctoral students he supervised as well: Adolf Busemann, Theodore von Kármán, Oskar Tietjens, Walter Tollmien and Hermann Schlichting.

References:

1. “100 Years of German Aerospace Research,” DLR
2. “Ludwig Prandtl,” Wikipedia