Numerical simulation of turbulent flows in complex geometries using the CVS approach based on orthonormal wavelet decomposition

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Turbulent reacting flows are characterized by their large range of active temporal and spatial scales. In most cases a decoupling of the small from the large spatial scales and the slow from the fast temporal scales cannot be achieved. Multiscale representations, such as wavelet bases, allow to circumvent this obstruction and are, therefore, promising for modelling and computing chemically reacting turbulent flows. The project is focused on the application of the newly developed Coherent Vortex Simulation (CVS) method to study the mixing in turbulent reacting flows. In the CVS method the conservation equations are solved in a compressed basis obtained by wavelet filtering. Compared to the state of the art in modelling, Large Eddy Simulation (LES) methods which discard the small scales and model its influence on the large scales of the flow, CVS automatically adapts the computational grid during the flow evolution to resolve the regions where strong gradients develop. Even though CVS calculations are performed in a highly compressed basis and, therefore, save computational resources, the results are very consistent with those obtained from DNS calculations, which are model free and resolve all scales. Thus, this new computational method is particularly well suited to study reacting flows where the chemical reactions mostly occur on fine scales and often very locally in space. The aim of this proposal is to develop new multiscale turbulence models and numerical codes based on CVS to accurately simulate turbulent reacting flows in complex geometries at high Reynolds numbers and high Schmidt numbers, as encountered in many applications in chemical engineering and in geophysical flows.