  In the last decade, progresses in additive manufacturing (AM) have paved the
way for optimized heat exchangers, whose disruptive design will depend on
predictive numerical simulations. Typical AM rough surfaces show limited
resemblance to the artificially constructed rough surfaces that have been the
basis of most prior fundamental research on turbulent flow over rough walls.
Therefore, a high-fidelity LES database is built to develop and assess novel
wall models for AM. This article investigates the flow in rough pipes built
from the surfaces created using AM techniques at Siemens based on Nickel Alloy
IN939 material. We developed a code to generate the desired rough pipes from
scanned planar surfaces and performed high-fidelity LES of turbulent rough pipe
flows at Re = 11,700 to reveal the influence of roughness on turbulence, mainly
the average roughness height and the Effective Slope. The equivalent sand-grain
roughnesses, ks, of the present AM rough surfaces are predicted using the
Colebrook correlation. In the present study, the existence of a logarithmic
layer is marked even for high values of ks. The mean flow, the velocity
fluctuations, and the Reynolds stresses show turbulence's strong dependence on
the roughness topography. Profiles of turbulence statistics are compared by
introducing an effective wall-normal distance. The effective distance collapses
the shear stresses and the velocity fluctuations outside the roughness
sublayer; thus, Townsend's similarity of the streamwise mean velocity is marked
for the present roughnesses. Furthermore, a mixed scaling is introduced to
improve the collapse of turbulence statistics in the roughness sublayer.
