2021/02/01 by Alexandre Vilquin, Julie Jagielka, Simeon Djambov +6 · 1 citation
Physics and Astronomy · #physics.flu-dyn
paper · pdf · doi:10.1126/sciadv.abc6234
published as Science Advances, American Association for the Advancement of Science (AAAS), 2021, 7 (5)
arxiv created 2021/02/01 · arxiv updated 2021/02/03
The friction f is the property of wall-bounded flows that sets the pumping cost of a pipeline, the draining capacity of a river, and other variables of practical relevance. For highly turbulent rough-walled pipe flows, f depends solely on the roughness length scale r, and the f -- r relation may be expressed by the Strickler empirical scaling f ∝ r(1)/(3). Here, we show experimentally that for soap film flows that are the two-dimensional (2D) equivalent of highly turbulent rough-walled pipe flows, f ∝ r and the f -- r relation is not the same in 2D as in 3D. Our findings are beyond the purview of the standard theory of friction but consistent with a competing theory in which f is linked to the turbulent spectrum via the spectral exponent α: In 3D, α = 5/3 and the theory yields f ∝ r(1)/(3); in 2D, α = 3 and the theory yields f ∝ r.