Problem to be solved: to provide a method of reducing resistance or resistance of an object, e.g., an aircraft, using a staggered periodic riblet.Solution: a first cyclic riblet (110) is formed on a smooth surface (104) of a physical object (100), and then a second periodic riblet (120) is formed.Flow occurs on the first and second periodic riblets.Each of the first, second and third periodic riblets has a second transfer region (145b) located at the first end (145a) and its second end (114, 124, 134) located at the first end (112, 122, 132).Each second transition region (145b) overlaps with each first transition region (145a).The length of each riblet of the first and second periodic riblets extends parallel to the direction of the flow.Selection diagram
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