“…This was attributed to the difference in turbulence production near the wall, which was concluded to be dependent on roughness height over rough walls rather than the viscous lengths associated with smooth wall flows. In general Blake concluded that for rough walls, roughness had the largest influence on medium and small scale turbulence structures, while unlike the findings of Aupperle and Lambert (1970), roughness spacing was speculated to have mild influence on the larger turbulence structures.…”