Secondary flows in turbulent boundary layers developing over truncated cone surfaces

The evolution of a turbulent boundary layer over truncated cones in staggered and random configurations is investigated using direct numerical simulations. Three planform densities one staggered, which closely match the configuration recent experiment by Womack et al. ( J. Fluid Mech. , vol. 933, 2022, A38), are considered. also used to validate present computations found reproduce flow measurements very accurately. Spanwise heterogeneity mean streamwise velocity form high low momentum pathways was detected both arrangements, indicating presence secondary flows cross-stream plane. arrangements much weaker confined near roughness crest, while they approach edge layer. We clear correlation with leading roughness, local topography weak for all cases studied. Vorticity transport analysis employed explore nature formed, highlighting strong vortex stretching roughness. impact on statistics, especially demonstrated breakdown outer-layer similarity.