SKIN-FRICTION DRAG REDUCTION USING THE METHOD OF SPANWISE MEAN VELOCITY GRADIENT

Jens H. M. Fransson
Linne Flow Centre Department of Mechanics KTH–Royal Institute of Technology SE–100 44 Stockholm, Sweden

Robert S. Downs III
Linne Flow Centre Department of Mechanics KTH–Royal Institute of Technology SE–100 44 Stockholm, Sweden

Sohrab S. Sattarzadeh
Linne Flow Centre Department of Mechanics KTH–Royal Institute of Technology SE–100 44 Stockholm, Sweden

Résumé

Over the last decade wind tunnel experiments and numerical simulations have shown that steady spanwise mean velocity gradients are able to attenuate the growth of different types of boundary layer disturbances if introduced in a controlled way. In this paper some different techniques to setup the spanwise mean velocity variations are discussed and their stabilizing effect leading to transition delay are quantified. This control strategy has potential to lead to an unforeseen positive impact on the broad spectrum of industrial applications where reducing drag is a daily challenge.