THE COMBINED DRAG EFFECTS OF RIBLETS AND POLYMERS IN PIPE-FLOW

The additional skin friction effect produced by a 3M riblet surface, u sed in conjunction with low concentration polymer solutions, is invest igated in fully developed, turbulent pipe flow. Generally at the low c oncentrations of Polyox 301 and guar gum studied, the absolute drag re duction of the 3M riblets appears to be independent of the polymer pre sence, with a maximum between 5 and 7 percent occurring around h+ = 12 . Comparisons with previous polymer studies with 3M riblets, sand roug hened and commercially rough surfaces are made.