Published online by Cambridge University Press: 04 July 2016
The work reported here extends the work of Nikuradse on the categorisation of surface roughness. Nikuradse’s work considered pipe flow, whilst in this paper boundary layer flow is investigated. Important and fundamental differences between these two types of flow are shown. An experiment upon turbulent boundary layers over sandpaper-type roughnesses enabled a fluid-mechanic categorisation of these surfaces to be obtained for this flow. This is compared with some shape and size categorisations of the roughnesses from detailed measurements.