Role of Vorticity in Generation of Pressure Sources and its Implication for Maintenance of Turbulence

Abstract

The Poisson equation for pressure, together with the evolutions equations for the velocity gradients, reveals the role of vorticity in generation of pressure sources. Specifically, it was shown how a pressure field created by a local source, acting on nearby vorticity, would create new pressure sources. It was further established that a moving pressure field, which moves with the velocity of its source, but extends well beyond the source location, could lead to generation of fast and slow streaks as wells as contribute to formation of flow structures in the wall region. These processes, which are part of central mechanisms of maintenance of turbulence, suggest that turbulence could be self-sustaining only if the perturbation pressure force could overcome the diffusion effects; the value of friction Reynolds number reflects the balance between the two.