A numerical and experimental study of the Blasius wall jet
Konferensbidrag (offentliggjort, men ej förlagsutgivet), 2003
In the current study the wall jet flow of high Reynolds number is investigated. As presented experimental and DNS results demonstrate, for such operating conditions a laminar flow similarity is not reached due to the happening flow breakdown and the three-dimensional effects are important. For the purpose of linear stability investigation, the problem of the flow description is resolved and a boundary-layer solution developing from coupled Blasius boundary layer and Blasius shear layer is implemented, valid in the close downstream field of a slot. Performed linear stability investigations reveal the high instability of two-dimensional eigenmodes and non-modal streaks, and the calculations agree reasonably well with the provided experiments. Furthermore, the nonlinear stage of laminar flow breakdown is studied both with three-dimensional direct numerical simulation and experimentally. A modelling of the "natural" experimental case is achieved using random noise simulations and it is clearly demonstrated that three-dimensional modes are important for the breakdown process. Additionally, a thorough investigation of the nonlinear interactions between the eigenmodes and streaks is made in the DNS and in the experiment with controlled parameters of the forcing.