1 Numerical investigation and preliminary modeling

Wall-resolved LES of a turbulent flow around a multi-perforated plate are presented. Periodic conditions are used in both directions tangential to the plate so that only one or a few micro-jets are computed. Comparisons between one and four holes computations show that single hole domain calculations allow to capture the essential characteristics and statistics of the flow. The results from two different numerical codes and strategies also compare favorably with the existing experimental data in the case of a large scale cold flow with effusion. The overall quality of the simulations being established, further analysis of the flow structure is performed. Two results relevant to further modeling studies are obtained: the jet angle somewhat departs from the hole angle and the velocity profile in the jet is highly inhomogeneous with a strong recirculation zone in the downstream side. Preliminary testing of a simple dynamic model for the normal velocity is also presented. A robust algorithm for implementing this model in coupled computational domains is developed. Deficiencies in the model are identified and discussed. 1