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General relativity describes the physical force of gravity and its relation with the space-time structure. The fundamental physical insight behind the theory of general relativity is that the effects of acceleration cannot be distinguished from those of gravity. The presence of matter changes the geometry of space and acceleration is experienced in relation to that geometry. In particular, the geometry of space and time is dynamically governed by physical laws that are not independently given. Such a case is the fluid turbulence which remained unexplained for over fifty years within the framework derived from the classical Navier-Stokes theory. The physical and mathematical problem of the genuine turbulence remains an unsolved one. This paper considers the turbulence as a manifestation of non-Newtonian behavior induced by the gravity-like accelerations at the beginning of motion. The fluid particles with high accelerations exhibit in wall-bound flows with large Reynolds number a sort of structure-less, background turbulence. It is shown that the relativistic viewpoint may solve the present paradigmatic crisis of turbulence. [ABSTRACT FROM AUTHOR]

In this paper we investigated numerically the dynamic stall phenomenon and the possibilities to control it, with application to vertical axis wind turbines (for urban users). The Phenomenon appear at low tip speed ratio (TSR<4) and it has a great impact on structural integrity of the wind turbine and power performances. For this reason we performed a computational study of dynamic stall around NACA 0012 airfoil in pitching motion at relative low Reynolds number (-105). Also, we performed the same analysis for four flow control methods: two passive (Gurney flap and slot) and two active (blowing jet on the rounded trailing edge and synthetic jet periodically activated). The Results are compared to those of an existing experimental case test. [ABSTRACT FROM AUTHOR]