The Combined Drag Effects of Riblets and Polymers in Pipe Flow

The additional skin friction effect produced by a 3M riblet surface, used in conjunction with low concentration polymer solutions, is investigated in fully developed, turbulent pipe flow. Generally at the low concentrations of Polyox 301 and guar gum studied, the absolute drag reduction of the 3M riblets appears to be independent of the polymer presence, with a maximum between 5 and 7 percent occurring around h⁺ = 12. Comparisons with previous polymer studies with 3M riblets, sand roughened and commercially rough surfaces are made.