Modelling roughness and receptivity in three-dimensional boundary-layers

Authors: Tempelmann, D., Schrader, L.-U., Hanifi, A., Brandt, L.B., Henningson, D.S.H.
Document Type: Conference
Pubstate: Published
Journal: Proceedings of the 7th TSFP conference
Year: 2011


The receptivity of a swept-wing boundary layer to lo- calised surface roughness is studied by means of direct nu- merical simulations (DNS). The ?ow case considered is meant to model wind tunnel experiments performed at the Arizona State University by Saric & coworkers. The receptivity am- plitude of the cross?ow disturbances predicted by the DNS is 40% of that measured in the experiments. The DNS results are then used to evaluate the performance of different recep- tivity models based on either the parabolised stability equa- tions or the ?nite Reynolds number theory (FRNT). In gen- eral it is found that receptivity amplitudes are well predicted for micron sized roughness elements if non-parallel effects are accounted for. ever, they did not model receptivity but extracted initial am- plitudes from experimental data. Nishino & Shariff (2009) performed a DNS but obtained receptivity amplitudes far be- low those measured in the experiments and suspected their roughness model to be inadequate. The aim of this study is to carefully compare different ap- proaches of modelling boundary layer receptivity to surface roughness. We use both direct numerical simulations and parabolised stability equations (PSE). The latter may be used in combination with their respective adjoint (APSE) to predict receptivity. Further, we compare to the FRNT results by Ng & Crouch (1999).