AE 2020 INTRODUCTIONA bit of historyFluid mechanics is a very old field. Over three centuries ago, Sir Isaac Newtondevoted an entire book in his work known as Principia Mathematicato fluid mechanics(1687). Newton believed that fluid dynamics could be modeled by viewing fluidmolecules as rigid particles that obey the classical particle equations of motion. Hedeveloped a model for the lift coefficient generated by the airfoils. This model assumedthat when the fluid particles hit a solid surface, they lose all their momentum in adirection normal to the surface, and thereafter slide down the sides of the body. Thismodel stated thata2sin2=lCIn 1777, D'Alembert (a French scientist) did a series of experiments on ships incanals, and proved that the above equation is wrong. In 1781, Euler (a Swiss Engineer)used theoretical reasoning to show that lift coefficient should be proportional to sinα,and not to sin2α. Later on we will see that lift behaves likeapsin2=lCFrom such humble beginnings and false steps, the field of fluid mechanics grew.Many researchers such as Lilienthal (1890s) and Langley (1906) worked on thedevelopment of airfoils, gliders and wings. Other researchers and engineers (Rankine1820-1872, Froude, de Laval, Pelton) worked on turbomachinery, pumps, wind mills andso on, which relied on aerodynamic principles.
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