| 主权项 |
1. An aerodynamic or hydrodynamic wall surface configured to modify the interaction of a boundary layer of a fluid flowing across the wall surface, comprising:
at least one array of roughness elements disposed on and extending from the wall surface, wherein each roughness element extends outwardly from the wall surface at one or more selected angles relative to the flow of fluid across the wall surface such that a preferential flow direction surface is formed, wherein each roughness element has a front, upstream surface and an opposing rear, downstream surface and a peripheral edge that has an upper portion that tapers to a top and a bottom portion that tapers to a base, which is connected to the wall surface, wherein a plurality of roughness elements are positioned substantially transverse to the flow of fluid across the wall surface such that a distance between a medial portion of the peripheral edges of adjacent and aligned roughness elements is less than the distance between the respective tops of the roughness elements and is less than the distance between the respective bases of the roughness elements, wherein the array of roughness elements defines a plurality of cavities, wherein the thickness of the boundary layer is at least 20% of a cavity height of each cavity such that shear layer instabilities of cavity vortexes that form in the plurality of cavities are reduced, wherein each roughness element comprises at least one riblet extending outwardly therefrom the front, upstream surface of the roughness element that is configured to aid in the formation and stability of cavity flows embedded between the roughness elements, and wherein each roughness element comprises at least one riblet extending outwardly from the rear, downstream surface of the roughness element, and wherein each riblet extends substantially longitudinally. |
