During the last century, the theoretical investigations in the boundary vorticity dynamics were based on the concept of a fluid of small-constant viscosity, i.e. the Newtonian fluid, described by the non-slip condition at the wall and the linear law for fluid friction. But the application of current ideas in non-linear hydrodynamic stability theory to the flow in shear layers showed the existence of a class of flows involving concentrations of vorticity, also visible both in experimental

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... ons and industrial environments. The role of concentrated vorticity in fluid dynamics phenomena, concerning both the vorticity creation at the boundary and the response/reaction to the flow field is not entirely understood. The main purpose of this paper is to bring about a better mechanism of vorticity creation at the wall beneath a flow using the concept of thixotropic fluid associated with an active vorticity governed by the vorticity transport equation that is able to react back on the fluid flow. Such a viscoelastic behavior can be easily forecasted by the relationship between the value of the critic Reynolds number, Re c , and the equilibrium kinetic viscosity 21 0 0 , Re c e     , argued in the sequel by means of the thixotropic fluid concept.