Mechanisms for generating coherent packets of hairpin vortices in channel flow. (English) Zbl 0946.76030

Zhou, J.; Adrian, R. J.; Balachandar, S.; Kendall, T. M.

J. Fluid Mech. 387, 353-396 (1999).

From the text: The evolution of a single hairpin vortex-like structure in the mean turbulent field of a low-Reynolds-number channel flow is studied by direct numerical simulation. First, we discuss the extraction of the initial structure using stochastic estimation methodology, and give a brief discussion of the numerical simulation and the vortex identification methodology. Then we examine the development of the initial structure into a hairpin packet. The growth and threshold behaviour for the autoregeneration process are discussed, followed by comparison of the computed vortical structure with the experimental measurements. The next topic is the generation of additional quasi-streamwise vortices and the convective velocity of the hairpin packet. Finally, we address the effect of asymmetry on the evolution of hairpin structures.

MSC:

76F10	Shear flows and turbulence
76D05	Navier-Stokes equations for incompressible viscous fluids
76M20	Finite difference methods applied to problems in fluid mechanics
76F65	Direct numerical and large eddy simulation of turbulence

Keywords:

convective velocity of hairpin packet; hairpin vortex-like structure; low Reynolds number channel flow; direct numerical simulation; stochastic estimation methodology; vortex identification; autoregeneration process; quasi-streamwise vortices