On the development of a turbulent boundary layer over staggered three dimensional cavities

Overview & Synopsis

Studies by Gowree et al. have suggested that staggeredthree dimensional circular cavities can potentially reducethe skin friction drag of a turbulent boundary layer de-veloping over a flat plate. This is true up to a certainReynolds number, after which the drag rapidly increases.The detailed mechanism behind the drag increase and thepossible skin friction drag reduction was not discussed,due to the limitations in the measurement technique. Inthe current experimental campaign the results found byGowree et al. have been confirmed, in addition, to moredetailed insight of the turbulent boundary layer over thefirst rows of cavities. Through numerical simulations weaim to give a heuristic explanation of the two distinct be-haviours. Here we report some quantitative evidence ofthe mechanism that may govern the drag increase, whichis the main focus of the current study. The modifica-tion of the flow field in the presence of the cavities pro-vides a qualitative explanation of the drag reduction ben-efit which is subjected for further investigation