Keywords: Structured surfaces Two-dimension 2D 3D flow drag reduction turbulence low speed streaks grooves
This section includes three parts:
Two_dimension structures or 2D longitudinal grooves
These structures include only ONE flow drag reduction mechanism. They are also called riblets.
They are longitudinal with constant shape and dimension in the MAIN flow direction
Three_dimension structures – Type 3D_1
These structures include TWO flow drag reduction mechanisms: longitudinal riblets with transversal (lateral) periodic displacement.
They present the same shape and dimension along the structure path i.e. the secondary local flow.
Three_dimension structures – Type 3D_2
These structures include THREE flow drag reduction mechanisms: longitudinal riblets with two orthogonal waves, one transversal periodic displacement plus one normal periodic displacement.
They present the same shape but varying height along the structure path i.e. the secondary local flow.