Study of the “Local” Link between a Passive Scalar and Its Dissipation Using the Wavelet Decomposition

It is now widely recognized that large coherent structures are key elements in the dynamics of turbulent flows, since it is known that they dominate the most important phenomena in these flows: turbulence production, turbulent diffusion, etc …. [1, 2]. The interest in these structures is growing because of their importance in understanding flow equilibrium. Statistical considerations such as conditional averages or conditional probability density functions (pdfs) have shown [3] that the inter-dependence between temperature and its dissipation is particularly strong in regions where turbulent flows are non isotropic or influenced by boundary conditions which make the temperature pdfs P(θ) asymmetric, whereas the correlation coefficient was found to result from frequencies between those associated with the integral scale and the Taylor micro-scale.