Wall roughness induces asymptotic ultimate turbulence

Xiaojue Zhu, Ruben Adriaan Verschoof, Dennis Bakhuis, Sander Gerard Huisman, Roberto Verzicco, Chao Sun* (Corresponding Author), Detlef Lohse (Corresponding Author)

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

20 Citations (Scopus)
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Abstract

Turbulence governs the transport of heat, mass and momentum on multiple scales. In real-world applications, wall-bounded turbulence typically involves surfaces that are rough; however, characterizing and understanding the effects of wall roughness on turbulence remains a challenge. Here, by combining extensive experiments and numerical simulations, we examine the paradigmatic Taylor–Couette system, which describes the closed flow between two independently rotating coaxial cylinders. We show how wall roughness greatly enhances the overall transport properties and the corresponding scaling exponents associated with wall-bounded turbulence. We reveal that if only one of the walls is rough, the bulk velocity is slaved to the rough side, due to the much stronger coupling to that wall by the detaching flow structures. If both walls are rough, the viscosity dependence is eliminated, giving rise to asymptotic ultimate turbulence—the upper limit of transport—the existence of which was predicted more than 50 years ago. In this limit, the scaling laws can be extrapolated to arbitrarily large Reynolds numbers.

Original languageEnglish
Pages (from-to)417-423
Number of pages7
JournalNature physics
Volume14
Issue number4
DOIs
Publication statusPublished - 12 Feb 2018

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