On turbulent spots

The turbulent spot is seen as a building block in the structure of the turbulent boundary layer, in spite of the fact that it contains numerous eddies. It is pointed out that the eddies in a transitional spot retain their preferred location and size in spite of the growth of the spot with increasing distance from the origin. A synthetic turbulent boundary layer generated by means of spots, triggered regularly in space and time, may differ slightly from the conventional boundary layer which is initiated by spots generated randomly. It is considered possible that it has preferred characteristics that may be used for engineering purposes.