Fundamentals of physics of fluid flow reconsidered

Recently, two significant defects of the state-of-the-art of theoretical fluid mechanics have been evidenced, namely the ambiguity of the Navier Stokes equations with respect to the viscous stress tensor, and the inconsistency of the Reynolds stress approach with the symmetry of the inertial tensor. Therefore, by means of two classical topics of fluid mechanics, namely the universal velocity profile and the laminar boundary layer, the physics of fluid flow are scrutinized. The validity of the so obtained results is tested at the example of an exact solution of the Navier Stokes equations, namely the diffusion of the circulation of an eddy.