Staggered periodic riblets

A physical object, comprising:

• a smooth surface:
• first periodic riblets on the smooth surface of a physical object;
• and
• second periodic riblets on the smooth surface of the physical object:
• wherein:
• each first periodic riblet comprises a first transition region at a first end of each first periodic riblet and a second transition region at a second end of each first periodic riblet:
• each second periodic riblet comprises a first transition region at a first end of each second periodic riblet and a second transition region at a second end of each second periodic riblet:
• each second transition region at the second end of each first periodic riblet overlaps each first transition region at the first end of each second periodic riblet;
• and
• a length of each riblet of the first and second periodic riblets runs parallel to a direction of the flow:
• a maximum height of each riblet of first and second periodic riblets is less than 0.002 inches:
• a maximum width of each riblet of the first and second periodic riblets is less than 0.004 inches;
• the length of each first and second riblet that runs parallel to the direction of flow is within a range of 8 to 100 times longer than the maximum height of each respective riblet-;
• and
• generating a constant cross-sectional area as measured above the smooth surface of the physical object is constant at any cross section through the first and second periodic riblets by compensating a decreasing volume of a trailing edge of each first and second periodic riblets with an increasing volume of neighboring periodic riblets.

A method of manufacturing a physical object, comprising:

• forming first periodic riblets on a smooth surface of a physical object;
• and
• forming second periodic riblets on the smooth surface of the physical object:
• wherein:
• each first periodic riblet comprises a first transition region at a first end of each first periodic riblet and a second transition region at a second end of each first periodic riblet:
• each second periodic riblet comprises a first transition region at a first end of each second periodic riblet and a second transition region at a second end of each second periodic riblet:
• each second transition region at the second end of each first periodic riblet overlaps each first transition region at the first end of each second periodic riblet;
• a length of each riblet of the first and second periodic riblets runs parallel to a direction of the flow:
• a maximum height of each riblet of first and second periodic riblets is less than 0.002 inches;
• a maximum width of each riblet of the first and second periodic riblets is less than 0.004 inches;
• the length of each first and second riblet that runs parallel to the direction of flow is within a range of 8 to 100 times longer than the maximum height of each respective riblet;
• and
• generating a constant cross-sectional area as measured above the smooth surface of the physical object is constant at any cross section through the first and second periodic riblets by compensating a decreasing volume of a trailing edge of each first and second periodic riblets with an increasing volume of neighboring periodic riblets.