1. Tube-Side Heat Transfer and Pressure Drop for Tubes Having Helical Internal Ridging with Turbulent/Transitional Flow of Single-Phase Fluid. Part 2. Multiple-Helix Ridging
2. Webb , R. L. , Turbulent Heat Transfer in Tubes Having Two-dimensional Roughness, Including the Effect of Prandtl Number , Ph.D. thesis , Department of Mechanical Engineering, University of Minnesota , Minneapolis , Minn. , September 1969 . See also Int. J. Heat Mass Transfer, vol. 14, pp. 601-617, 1971, and vol. 15, pp. 1647-1658, 1972 .