A fast direct numerical simulation method for characterising hydraulic roughness

D. Chung, L. Chan, M. Macdonald, N. Hutchins, A. Ooi

Research output: Contribution to journalArticle

37 Citations (Scopus)


We describe a fast direct numerical simulation (DNS) method that promises to di- rectly characterise the hydraulic roughness of any given rough surface, from the hy- draulically smooth to the fully rough regime. The method circumvents the unfavourable computational cost associated with simulating high-Reynolds-number flows by employ- ing minimal-span channels (Jiḿenez & Moin 1991). Proof-of-concept simulations demon- strate that flows in minimal-span channels are sufficient for capturing the downward velocity shift, that is, the Hama roughness function, predicted by flows in full-span chan- nels. We consider two sets of simulations, first with modelled roughness imposed by body forces, and second with explicit roughness described by roughness-conforming grids. Ow- ing to the minimal cost, we are able to conduct DNSs with increasing roughness Reynolds numbers while maintaining a fixed blockage ratio, as is typical in full-scale applications. The present method promises a practical, fast and accurate tool for characterising hy- draulic resistance directly from profilometry data of rough surfaces.

Original languageEnglish
Pages (from-to)418-431
Number of pages14
JournalJournal of Fluid Mechanics
Publication statusPublished - 01 Jan 2015

All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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