COHERENT STRUCTURE DYNAMICS IN TURBULENT CHANNEL FLOW

Authors:
  • LPLeonardo Primavera
    Leonardo Primavera
  • GAGiancarlo Alfonsi
    Giancarlo Alfonsi
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Abstract
The dynamics of coherent structures in the near-wall region of a turbulent channel flow at Reynolds number Re = 40,000 (based on bulk velocity and channel half-width) is investigated. The technique of the Proper Orthogonal Decomposition (POD) is applied to extract the coherent structures of the flow from a turbulent flow database obtained with the use of a finite volume computational code for the numerical integration of the three-dimensional time-dependent incompressible Navier-Stokes equations; for turbulence modeling the LES (Large Eddy Simulation) approach is followed and the RNG (Renormalization Group technique) Sub Grid-Scale closure is used. The three-dimensional time-dependent velocity field is computed and 100 non-dimensional time steps of the turbulent statistically steady state are considered for the decomposition of the flow field. Results are presented in terms of numerical visualizations of streamwise vorticity, showing the temporal dynamics of structures and the different phases of the turbulent activity near the wall.