ANGULAR-MOMENTUM CONSERVATION LAW AND NAVIER-STOKES THEORY

A Navier-Stokes fluid is defined to be an isotropic, non-micromorph ma terial for which a linear relation between the viscous pressure tenser and the stretching holds in every theoretical flow situation. However , as to the dynamical representation of this fluid's state quantities, the conservation law of angular momentum is generally ignored. The pa per deals with the impact of this principle on the mathematical struct ure of the ordinary Navier-Stokes equation of motion. It is known that the physics of fluids is strongly influenced by the form of the dissi pation law which is assumed to be valid. Obviously, most of the real f low patterns cannot be described adequately by this fluid model unless the well-known paradoxes of the equation's solutions are accepted in practice. This is especially true for incompressible hows. Thus, sever e consequences for the vorticity equation are inevitable; particularly , the theory of turbulent flows is strongly affected. Hence, engineeri ng work is considerably influenced. Why these fundamental conclusions are widely disregarded in research and education is discussed. The ina dequate behavior is mainly caused by the traditional viewpoint of clas sical mechanics which is founded on incomplete conservation laws. A re alistic flow field description, however, may be established by means o f non-equilibrium concepts for the stress rate quantities. A respectiv e new theory of thermofluid dynamics is briefly summarized. It allows the elimination of some serious inconsistencies which are inherent in the present state of the Navier-Stokes theory.