A method for producing an object with riblets on and/or in the surface, around which object a fluid flows during use. A frictional resistance acting on a surface region along a flow direction during a flow around the object in the fluid is calculated and added up to a cumulative frictional resistance over a length of the surface region in the flow direction, after which the riblets are provided on and/or in a partial region of the surface in which an increase in the cumulative frictional resistance is at least 0.9, in particular greater than 1.0 to 0.9. Moreover, a method is provided for modifying a surface of an object around which a fluid flows during use, such as a foil. A structure having riblets is created on and/or in the surface, which structure reduces flow resistance of the object. Furthermore, a fluid flows around an object during use.

In one embodiment, a method for reducing drag includes forming a smooth surface on a first portion of a physical object. The method also includes forming periodic riblets on a second portion of the physical object. The method further includes generating a flow over the periodic riblets of the second portion of the physical object and over the smooth surface of the first portion of the physical object. The second portion of the physical object is adjacent to the first portion of the physical object. Each peak of each riblet of the periodic riblets of the second portion of the physical object is located above a plane of the smooth surface of the first portion of the physical object. Each valley between adjacent riblets of the periodic riblets of the second portion of the physical object is located below the plane of the smooth surface of the first portion of the physical object. A length of each riblet of the periodic riblets runs parallel to a direction of the flow.

A bonded body wherein functional base material is attached to object to be bonded. Functional base material and object are bonded with functional base material's end portion covered so operational effect neither lost nor adversely affected by fluid, bonded body has strong bonding property preventing functional base material peeled off due to weather. Peelability allows functional base material repair ease. Functional base material provided on object's curved surface to be bonded to along curved and/or smooth surface of object to be bonded to along smooth surface. Functional base material has peripheral side surface with peripheral distal-most end portion. Peripheral gap part provided between object to be bonded to and functional base material on inside of peripheral distal-most end portion and on side opposing to object to be bonded to. Peripheral gap part filled with holding member extending in laminar fan shape from peripheral side surface along curved and/or smooth surface.

A bonded body wherein functional base material is attached to object to be bonded. Functional base material and object are bonded with functional base material's end portion covered so operational effect neither lost nor adversely affected by fluid, bonded body has strong bonding property preventing functional base material peeled off due to weather. Peelability allows functional base material repair ease. Functional base material provided on object's curved surface to be bonded to along curved and/or smooth surface of object to be bonded to along smooth surface. Functional base material has peripheral side surface with peripheral distal-most end portion. Peripheral gap part provided between object to be bonded to and functional base material on inside of peripheral distal-most end portion and on side opposing to object to be bonded to. Peripheral gap part filled with holding member extending in laminar fan shape from peripheral side surface along curved and/or smooth surface.

A linear step discontinuity on the lower surface of the lifting surface is disclosed extending from the front of the lifting surface, possibly the leading edge, and may extend in the direction of the line of flight towards the trailing edge. The linear step discontinuity represents a step up if moving from the outboard end to the inboard end, such that in use fluid moving over the lifting surface tumbles over the linear step discontinuity to create a vortex in the fluid passing over the upper surface. The lifting surface may be an aircraft wing or in particular a winglet on an aircraft wing. The linear step discontinuity may be provided by the straight edge of a semi-circular object integrated into or adhered to the surface of the lifting surface.

A turbomachine includes a rotor and a stator, the stator having a plurality of profiled structures, each profiled structure being elongated in a direction of elongation in which the profiled structure has a length exposed to an airflow, and having a leading edge and/or a trailing edge, at least one of which is profiled and has, in said direction of elongation, serrations defined by a succession of peaks and troughs and having a geometric pattern transformed, over at least a part of said length exposed to the airflow, by successive scaling, via multiplicative factors, in the direction of elongation and/or transverse to the direction of elongation. The geometric pattern, as defined with reference to a radial distribution of the integral scale of the turbulence, evolves in a non-periodic manner.

A turbomachine includes a rotor and a stator, the stator having a plurality of profiled structures, each profiled structure being elongated in a direction of elongation in which the profiled structure has a length exposed to an airflow, and having a leading edge and/or a trailing edge, at least one of which is profiled and has, in said direction of elongation, serrations defined by a succession of peaks and troughs and having a geometric pattern transformed, over at least a part of said length exposed to the airflow, by successive scaling, via multiplicative factors, in the direction of elongation and/or transverse to the direction of elongation. The geometric pattern, as defined with reference to a radial distribution of the integral scale of the turbulence, evolves in a non-periodic manner.

An aircraft airfoil having a wave assembly. The airfoil may include a leading edge, a trailing edge position opposite the leading edge, a pressure side extending between the leading edge and the trailing edge, and a suction side extending between the leading edge and the trailing edge. The suction side may be positioned opposite the pressure side. The airfoil may also include a wave assembly positioned on the suction side of the body. The wave assembly may include at least one leading edge flexural actuator positioned adjacent the leading edge of the body. The wave assembly may also include a flexible member having a first end portion affixed to the at least one leading edge flexural actuator, and a second end portion positioned opposite the first end portion, and adjacent the trailing edge of the body.

An aircraft airfoil having a wave assembly. The airfoil may include a leading edge, a trailing edge position opposite the leading edge, a pressure side extending between the leading edge and the trailing edge, and a suction side extending between the leading edge and the trailing edge. The suction side may be positioned opposite the pressure side. The airfoil may also include a wave assembly positioned on the suction side of the body. The wave assembly may include at least one leading edge flexural actuator positioned adjacent the leading edge of the body. The wave assembly may also include a flexible member having a first end portion affixed to the at least one leading edge flexural actuator, and a second end portion positioned opposite the first end portion, and adjacent the trailing edge of the body.

Multilayer riblet appliques are disclosed. An example riblet applique includes a fluorosilicone riblet structure including riblet ridges and a base from which the riblet ridges extend, and a support layer proximate the fluorosilicone riblet structure. The support layer includes a vacuum-plasma-treated polymer film having a first surface and a second surface opposite the first surface, and a polymer sub-layer proximate the second surface of the polymer film.