ABSTRACT
This chapter examines the forces that are exerted on a body moving through a fluid. It describes the effects that cause lift and drag forces to be exerted on immersed bodies. The chapter examines flow past a flat plate, with particular interest in the fluid velocity in the vicinity of the plate surface. Along the plate surface, the velocity is zero due to the nonslip condition. The velocity profile increases from zero at the wall to the free stream value or nearly so at a certain vertical distance from the plate. This vertical distance, called the boundary layer thickness. The chapter describes the concept of streamlining. It determines the cause of lift and drag on different airfoils. Abundant data on lift and drag of various airfoils have been obtained by wind tunnel testing. The results of such tests are typically presented as plots of lift and drag coefficients versus angle of attack.
