Coherent Vortex Extraction in 3D Turbulent Flows Using Orthogonal Wavelets

This Letter presents a wavelet technique for extracting coherent vortices from three-dimensional turbulent flows, which is applied to a homogeneous isotropic turbulent flow at resolution ${N=256\mathrm{}}^3$. The coherent flow is reconstructed from only $3\%N$ wavelet coefficients that retain the vortex tubes, and $98.9\%$ of the energy with the same $k^{-5/3\mathrm{}}$ spectrum as the total flow. In contrast, the remaining $97\%N$ wavelet coefficients correspond to the incoherent flow which is structureless, decorrelated, and whose effect can therefore be modeled statistically.