You learned something different then because this finding is that some kinds of additional roughness delay the transition to turbulent flow which is pretty clear in the article.
replyhttps://phys.org/news/2014-01-smooth-rough-surfaces.html
replyA quick search looks to show the same general topic from more than a decade ago. I too have a recollection of this being discussed in the late 80s or early 90s. Maybe some folk wisdom that's just now getting quantified.
Thanks for clarifying.
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