We begin the study of fluid mechanics by pointing out the differences between fluids and solids, and by describing a flow in terms of the motion of elementary fluid parcels. As the volume of a fluid parcel becomes infinitesimal, the parcel reduces to a point particle, and the average velocity of the parcel reduces to the local fluid velocity computed well before the molecular nature of the fluid becomes apparent. The study of the motion and deformation of material lines and surfaces consisting of collections of point particles reveals the nature, and illustrates the diversity of motion in the world of fluid mechanics. Numerical methods allow us to study the kinematical structure of a flow with a specified velocity distribution obtained by analytical, numerical, or experimental methods.
KeywordsStagnation Point Point Particle Bilinear Interpolation Elementary Motion Axisymmetric Flow
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