DOI: 10.1615/THMT-18
ISBN Print: 978-1-56700-468-7
ISBN Online: 978-1-56700-467-0
ISSN Print: 2377-2816
Post Roughness Dominant Regime in the Turbulent Flow Through Rough Pipes
SINOPSIS
The influence of the surface roughness on the turbulence structures has been studied extensively experimentally and numerically. It is well known that in addition to the size of the rough elements, their spatial distribution also affects the turbulence. Pioneering study of Nikuradse showed that the turbulence in not affected in Laminar, transitional and early turbulent regimes by presence of the roughness and this effect just becomes dominant only at high Reynolds numbers.
In the present work, the effect of the roughness geometry (height and spatial distribution) on the friction factor
is experimentally investigated. Our main goal was to acquire data of carefully defined rough surfaces for further analytical and theoretical studies. However, unexpectedly, our results show that at high enough Reynolds number the classically fully rough regimes (constant friction factor) ends and normal smooth behaviour resumes. To our knowledge such a phenomenon has not been mentioned in the literature before.