Abstract: [Object] To provide a riblet structure that increases resistance reducing performance and is easily manufacturable, and an object including such a structure on a surface thereof. [Solving Means] This riblet structure includes a plurality of wave-shaped riblets on a surface thereof, in which each of the riblets has a smaller peak height as an angle formed between a ridge line and a fluid flow direction becomes larger, a width between peak bases in a direction orthogonal to the fluid flow direction becomes smaller as the angle becomes larger, and an angle formed between a slope of a peak of the riblet and the surface at the peak base or a curvature at the peak base is identical at any position in a cross-sectional shape in the direction orthogonal to the fluid direction.

Abstract: The present invention provides a riblet structure that further reduces drag, which is a sum of turbulent friction drag and pressure drag, and an object including such a riblet structure. An object such as an aircraft, plant, and pipeline includes a wavelike riblet pattern on a surface. The wavelike riblet pattern includes a large number of wavelike riblets. Each of the large number of wave riblets includes a wavelike ridge line, and a height thereof changes cyclically with respect to a fluid flow direction. With such a configuration, drag, which is a sum of turbulent friction drag and pressure drag, can be further reduced.

Abstract: The present invention provides a riblet structure that further reduces drag, which is a sum of turbulent friction drag and pressure drag, and an object including such a riblet structure. An object such as an aircraft, plant, and pipeline includes a wavelike riblet pattern on a surface. The wavelike riblet pattern includes a large number of wavelike riblets. Each of the large number of wave riblets includes a wavelike ridge line, and a height thereof changes cyclically with respect to a fluid flow direction. With such a configuration, drag, which is a sum of turbulent friction drag and pressure drag, can be further reduced.