Coherent Vorticity Extraction in 3D Homogeneous Isotropic Turbulence: Influence of the Reynolds Number and Geometrical Statistics

Benjamin Kadoch (1) , Margarete Oliveira Domingues (2) , Ingmar Broemstrup (3) , Lionel Larchevêque (1) , Kai Schneider (4) , Marie Farge (5)

1 IUSTI - Institut universitaire des systèmes thermiques industriels
2 Associated Laboratory of Computation and Applied Mathematics (LAC/CTE)
3 University of Maryland [College Park]
4 M2P2 - Laboratoire de Mécanique, Modélisation et Procédés Propres
5 CNRS - Centre National de la Recherche Scientifique

The coherent vorticity extraction method (CVE) is based on the nonlinear filtering of the vorticity field projected onto an orthonormal wavelet basis made of compactly supported functions. CVE decomposes each turbulent flow realization into two orthogonal components: a coherent and an incoherent random flow. They both contribute to all scales in the inertial range, but exhibit different statistical behavior. We apply CVE to 256 3 subcubes extracted from 3D homogeneous isotropic turbulent flows at different Taylor microscale Reynolds numbers (R λ = 140, 240 and 680), computed by a direct numerical simulation (DNS) at different resolutions (N = 256 3 , 512 3 and 2048 3), respectively. We compare the total, coherent and incoherent vorticity fields obtained by using CVE and show that few wavelets coefficients are sufficient to represent the coherent vortices of the flows. Geometrical statistics in term of helicity are also analyzed and the λ 2 criterion is applied to the filtered flow fields.

Mots clés: coherent structures; direct numerical simulation; isotropic turbulence; wavelets

Domaines: Mécanique des fluides [physics.class-ph]

Benjamin Kadoch, Margarete Oliveira Domingues, Ingmar Broemstrup, Lionel Larchevêque, Kai Schneider, et al.. Coherent Vorticity Extraction in 3D Homogeneous Isotropic Turbulence: Influence of the Reynolds Number and Geometrical Statistics. Brazilian Journal of Physics, 2009, 39. ⟨hal-02081129⟩