Experimental Investigation of the Turbulence Production Mechanism in Boundary Layers

摘要

Over the past year we have discovered the mechanism of production of the long streaks and a mechanism for creation of vortex ring-like typical eddies, and have demonstrated the occurrence of both within a real turbulent boundary layer. These aspects were the missing links needed to complete the conceptual structural model. This model de-emphasizes the importance of hairpin vortices in wall layer transport. However, experimental determination of the relative importance of each of the elements of the model in low Reynolds number layers is far from complete, and we know very little of the Reynolds number dependence or pressure gradient dependence of the model. What we have learned so far suggests several critical parameters that can be manipulated to control the production of turbulence and hence reduce drag. In the proposed research we want to focus on acquiring additional data to support the rational theory that has been formed so as to provide the basis for determining how much leverage we have in our efforts to control boundary layer turbulence.