PASSIVE TECHNIQUES FOR CONTROL OF TURBULENCE IN WALL-BOUNDED FLOWS

摘要

In this paper, the results obtained by the implementation of two widely used passive techniques for control of turbulence in wall-bounded flows - riblets and wall protrusions -are reviewed. The work is limited to the incompressible-flow case. In recent times, much interest has been devoted to active techniques for turbulence control (mainly sensors coupled with actuators) that, in turn, have never led to results comparable with those obtained by passive means. Moreover, with respect to the active, passive techniques can be more easily implemented in flows of applicative interest and their potential in controlling turbulence has been not yet completely explored. A point is made on the interpretation of the physical phenomena that give rise to the wall-protrusion technology for wall-turbulence control, actually offering a different point of view on those phenomena with respect to past researches.