NEWTURB · New eddy-simulation concepts and methodologies for frontier problems in Turbulence

Advances in transportation, energy harvesting, chemical processing, climatology, atmospheric and marine pollution are obstructed by the lack of understanding of turbulence. The turbulent energy transfer toward small-scales is characterized by highly non-Gaussian and out-of-equilibrium fluctuations that cannot be described by mean-field theories or traditional closure approximations. State-of-the-art computers and algorithms do not allow to perform brute-force direct numerical simulations of any realistic turbulent configuration: modelling is mandatory. On the other hand, turbulence models are often strongly limited by our lack of understanding of fundamental mechanisms. As a result, we have a deadlock: turbulence is thought of as ‘unsolvable’ theoretically and computationally ‘intensive’. Indeed, progress by using conventional methods has been slow. Last year, however, something new happened. Two unconventional conceptual and numerical methodologies to study Navier-Stokes equations appeared based on: (i) a surgery of nonlinear interactions with different Energy and Helicity contents, (ii) a fractal-Fourier decimation. These unexplored tools are potential breakthroughs to unravel the basic mechanisms governing the turbulent transfer in isotropic, anisotropic and bounded flows, e.g. the mechanism behind the growth of small-scales vorticity and formation/stability of coherent structures, a challenge that has defeated all numerical and theoretical attempts, up to now. The ultimate goal of NewTURB is to integrate the fresh knowledge achieved by using these novel numerical instruments to push forward the frontiers of turbulence modelling, exploiting the possibility to reduce the number-of-degrees-of-freedom in an innovative way to deliver alternative frontier ‘multiscale eddy-simulations’ methodologies for both unbounded and bounded flows with smooth walls or with heterogeneous landscapes, e.g. flows over a rough surface.