Flow, Turbulence and Combustion

, Volume 66, Issue 4, pp 393–426

Coherent Vortex Simulation (CVS), A Semi-Deterministic Turbulence Model Using Wavelets

  • Marie Farge
  • Kai Schneider
Article

DOI: 10.1023/A:1013512726409

Cite this article as:
Farge, M. & Schneider, K. Flow, Turbulence and Combustion (2001) 66: 393. doi:10.1023/A:1013512726409

Abstract

In the spirit of Ha Minh's semi-deterministic model, we propose a new method for computing fully-developed turbulent flows, called Coherent Vortex Simulation (CVS). It is based on the observation that turbulent flows contain both an organized part, the coherent vortices, and a random part, the incoherent background flow. The separation into coherent and incoherent contributions is done using the wavelet coefficients of the vorticity field and the Biot–Savart kernel to reconstruct the coherent and incoherent velocity fields. The evolution of the coherent part is computed using a wavelet basis, adapted at each time step to resolve the regions of strong gradients, while the incoherent part is discarded during the flow evolution, which models turbulent dissipation. The CVS method is similar to LES, but it uses nonlinear multiscale band-pass filters, which depend on the instantaneous flow realization, while LES uses linear low-pass filters, which do not adapt to the flow evolution. As example, we apply the CVS method to compute a time developing two-dimensional mixing layer and a wavelet forced two-dimensional homogeneous isotropic flow. We also demonstrate how walls or obstacles can be taken into account using penalization and compute a two-dimensional flow past an array of cylinders. Finally, we perform the same segmentation into coherent and incoherent components in a three-dimensional homogeneous isotropic turbulent flow. We show that the coherent components correspond to vortex tubes, which exhibit non-Gaussian statistics and long-range correlation, with the same k−5/3power-law energy spectrum as the total flow. In contrast, the incoherent components correspond to an homogeneous random background flow which does not contain organized structures and presents an energy equipartition together with a Gaussian PDF of velocity. This justifies their elimination during the CVS computation to model turbulent dissipation.

coherent structures Coherent Vortex Simulation (CVS) semi-deterministic model turbulence wavelets 

Copyright information

© Kluwer Academic Publishers 2001

Authors and Affiliations

  • Marie Farge
    • 1
  • Kai Schneider
    • 2
  1. 1.Laboratoire de Météorologie Dynamique, Ecole Normale Supérieure de ParisParis Cedex 05France
  2. 2.Laboratoire de Modélisation et Simulation Numérique en Mécanique & Centre de Mathématiques et d'Informatique, Université de ProvenceMarseille Cedex 13France

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