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SPECTRAL ANALYSIS ON REYNOLDS STRESS TRANSPORT EQUATION IN HIGH RE WALL-BOUNDED TURBULENCE

Myoungkyu Lee
Department of Mechanical Engineering University of Texas at Austin 201 E 24th St, Austin, Texas 78712, USA

Robert D. Moser
Department of Mechanical Engineerng and Institute for Computational Engineering and Sciences University of Texas at Austin 201 E 24th St, Austin, Texas 78712, USA

Аннотация

Despite its importance in many applications, the nature of wall-bounded turbulent flow is not well-understood. The dynamics of near-wall turbulence has been well studied, with direct numerical simulation (DNS) making an important contribution. It has been difficult to study the interaction of near-wall and outer-layer turbulence via DNS because the Reynolds numbers available via DNS have not been sufficiently high to exhibit significant scale separation. In the work presented here, we correct that short-coming.
We have performed direct numerical simulation(DNS) of turbulent channel flow using a Fourier-Galerkin method in the streamwise(x) and spanwise (z) directions and a B-Splines collocation method in the wall-normal (y) direction. The highest Reynolds number based on shear velocity (uτ = √(τw/ρ)), Reτ is approximately 5200.
To study the scale dependence of the dynamics of the Reynolds stress components, we applied a spectral analysis to the terms in the Reynolds stress transport equation (RSTE). Result shows that the large (or very large) scale motion has an important role in turbulent transport terms. Also, it has been observed that a non-trivial portion of turbulent kinetic energy (TKE) is transported to the near-wall region and dissipated by large scale motion.