Turbulent flow and friction in a pipe with repeated rectangular ribs

Measurements were conducted in the fully developed turbulent flow in a pipe with internal diameter D at a Reynolds number of Re _D= 1.6 × 10 ⁵ . The pipe walls were equipped with regularly spaced square ribs of relative height h/ D= 0.154 , while the pitch-to-roughness height was varied between p/ h= 1.67 and p/ h= 6.67 ....