What German engineer who pioneered the development of rigorous systematic mathematical analyses which he used for underlying the science of aerodynamics, which have come to form the basis of the applied science of aeronautical engineering, also developed the Mixing length model in the early 20th century?
Mixing length model: In fluid dynamics, the mixing length model is a method attempting to describe momentum transfer by turbulence Reynolds stresses within a newtonian fluid boundary layer by means of an eddy viscosity. Mixing length model:  The model was developed by Ludwig Prandtl in the early 20th century. Ludwig Prandtl: Ludwig Prandtl (4 February 1875 – 15 August 1953) was a German engineer. Ludwig Prandtl:  He was a pioneer in the development of rigorous systematic mathematical analyses which he used for underlying the science of aerodynamics, which have come to form the basis of the applied science of aeronautical engineering.
Ludwig Prandtl