6. Method for solving flow problems

The method for solving fluid mechanics problems differs from the methods used in the dynamics of undeformable solids in that the element under study is a continuous medium. A particle is defined as a population of molecules large enough to be considered as a continuous medium, and small enough that the usual physical quantities can be considered as uniform. The surface separating this set of particles from the external medium is denoted by Ω (figure 22 ). This surface Ω can be mobile over time and follow the particles as they move. In this case, we're analyzing the evolution of a closed system. It can be immobile, i.e. linked to the reference space, in which case the particles inside the volume V bounded by the surface Ω change as a function of time. In this case,...