Flows of Viscous Fluids

Abstract

It was shown above that the flow of an ideal fluid in the field of a potential force produces no vortexes,—i.e., a potential flow remains potential at any time. In real flows, however, we regularly observe a production and destruction of vortexes. This is because the real fluid is a viscous one. The assumption that there is a slip at the boundary between a flowing fluid and a solid (as in the case of an ideal fluid) also turns out to be incorrect for a real fluid. All components of the velocity vanish on the surface of a body at rest, according to experiments. That is why the dust accumulates on the surfaces of bodies even when flow exists past these bodies (the dust on blades of a fan, for example).