Jean-Baptiste Charles Joseph Bélanger (4 April 1790 – 8 May 1874) was a French applied mathematician who worked in the areas of hydraulics and hydrodynamics. He was a professor at the École Centrale des Arts et Manufactures, École Polytechnique and École des Ponts et Chaussées in France. In hydraulic engineering, he is often credited improperly for the application of the momentum principle to a hydraulic jump in a rectangular open channel in 1828. His true contribution in 1828 was the development of the backwater equation for gradually varied flows in open channels (Bélanger 1828) and the application of the momentum principle to the hydraulic jump flow in 1838. (Bélanger 1841) Source: Wikipedia (en)