THE FOUNDER OF MODERN FLUID DYNAMICS: LUDWIG PRANTDL
A fluid is defined as a substance that does not have any determined shape and is deformed continuously by a shear force, thus it can be said that fluid mechanics is considered as a part of physics which is concerning about gases, liquids and plasmas, in the other words, no solid phases. Modern fluid mechanics is based on Continuum Hypothesis. This hypothesis assumes that a matter is continuous, hence while a matter is examined, atomic structure is not regarded- because if a matter is analyzed at a microscopic scale, the matter will be observed as discrete- and macroscopic scale is preferred instead of microscopic scale.
Fluid mechanics can be divided into some subtitles, and these are fluid static (at rest) and fluid dynamic (in motion). These sections of fluid mechanics follow historical progression. In history, Archimedes thought about fluids firstly and his ideas were the entry of fluid static, and then Leonardo Da Vinci examined behaviors of complex flow. The important breakthrough about fluid dynamic appeared thanks to luminaries in Newtonian physics; they are Isaac Newton, Leonhard Euler and Daniel Bernoulli etc. Pressure as being three dimensional and velocity of fluid were explained thanks to Euler equations, but the equations were not enough to clarify the viscosity (friction) in a flow field. In the next century, Euler equations were developed by Claude-Louis Navier and George Stokes independently, and then new equations were derived and nowadays they are known as Navier-Stokes equations. These equations provided to describe internal friction acting in a flow field, but could not explain friction between a flow and a surface which contacts with the flow. The relationship, in the other words, is that forces which acting between flow and surface were realized with the first airplane designed by Wright Brothers. The forces were caused by two reasons. These are the fluid pressure and the shear stress due to the friction. The pressure was explained easily with some assumptions such as the flow was assumed inviscid. However, the shear stress was not calculated with those assumptions which were used to describe the pressure, because flow ought to be viscous for calculating the shear stress. Therefore, any flow could not be defined highly near to a solid body completely, and this problem in fluid mechanics could not be solved until the Prandtl’s presentation about boundary layer on 8 August 1904.
Ludwig Prandtl was born on 4 February 1875. He was the single child of his family and his mother had chronic illness; thus while Prandtl was growing up, he spent the most of his time with his father and they were together all the time. His father was a professor of engineering and Prandtl was under the influence of him so that Prandtl began to concern himself with physics. He started a technique university and his teacher was a famous professor, August Foppl. Prandtl had graduated for...