A method for reducing drag, comprising: forming smooth surfaces (122, 142) on a plurality of first portions (120, 140) of a physical object; forming periodic riblets on a plurality of second portions of the physical object, wherein: each riblet of the periodic riblets is the same length; the smooth surface (122, 142) of each of the plurality of first portions (120, 140) of the physical object is the same length as the periodic riblets; adjacent first portions (120, 140) of smooth surfaces (122, 142) and second portions of riblets form an intermittent repeating riblet pattern along a predetermined length of the physical object and along a predetermined direction of flow; and further wherein each riblet of the periodic riblets of the plurality of second portions of the physical object is depressed below a plane of the smooth surface (122, 142) of the plurality of first portions (120, 140) of the physical object; generating a flow over the periodic riblets of the plurality of second portions of the physical object and over the smooth surface of the plurality of first portions (120, 140) of the physical object, wherein a length of each riblet of the periodic riblets runs parallel to the direction of the flow. forming smooth surfaces (122, 142) on a plurality of first portions (120, 140) of a physical object; forming periodic riblets on a plurality of second portions of the physical object, wherein: each riblet of the periodic riblets is the same length; the smooth surface (122, 142) of each of the plurality of first portions (120, 140) of the physical object is the same length as the periodic riblets; adjacent first portions (120, 140) of smooth surfaces (122, 142) and second portions of riblets form an intermittent repeating riblet pattern along a predetermined length of the physical object and along a predetermined direction of flow; and further wherein each riblet of the periodic riblets of the plurality of second portions of the physical object is depressed below a plane of the smooth surface (122, 142) of the plurality of first portions (120, 140) of the physical object; generating a flow over the periodic riblets of the plurality of second portions of the physical object and over the smooth surface of the plurality of first portions (120, 140) of the physical object, wherein a length of each riblet of the periodic riblets runs parallel to the direction of the flow. each riblet of the periodic riblets is the same length; the smooth surface (122, 142) of each of the plurality of first portions (120, 140) of the physical object is the same length as the periodic riblets; adjacent first portions (120, 140) of smooth surfaces (122, 142) and second portions of riblets form an intermittent repeating riblet pattern along a predetermined length of the physical object and along a predetermined direction of flow; and further wherein each riblet of the periodic riblets of the plurality of second portions of the physical object is depressed below a plane of the smooth surface (122, 142) of the plurality of first portions (120, 140) of the physical object; generating a flow over the periodic riblets of the plurality of second portions of the physical object and over the smooth surface of the plurality of first portions (120, 140) of the physical object, wherein a length of each riblet of the periodic riblets runs parallel to the direction of the flow.