TOWARDS A NEW MODEL-FREE SIMULATION OF HIGH-REYNOLDS-FLOWS - LOCAL AVERAGE DIRECT NUMERICAL-SIMULATION

Studies on the numerical simulation of high-Reynolds-number flows enco unter difficulties due to the wide range of characteristic length and time scales existing in the flow field. These are often much smaller t han the computational grid size. A new approach based on a 'model-free ' local average direct numerical simulation is presented which incorpo rates a strategy to filter the non-resolvable scales by means of an in tegration over the domain and to recover the contribution of the subgr id scales by using an integral formulation developed for them. The res ulting weak formulation allows us to define a numerical flux that, tha nks to the filtering operation, is highly accurate. Several computatio n test-cases concerning theoretical accuracy and the Navier-Stokes equ ations at high Reynolds number are carried out without using any turbu lence model. The obtained accuracy for all computations confirms that this approach can be considered a valid contribution in the field of d irect numerical simulation.