Feasibility of skin-friction diagnostics based on surface pressure gradient field

Tianshu Liu, Takashi Misaka, Keisuke Asai, Shigeru Obayashi, Jie Zhi Wu

Research output: Contribution to journalArticlepeer-review

13 Citations (Scopus)

Abstract

An intrinsic relation is given between the skin-friction vector and the surface pressure gradient through the boundary enstrophy flux (BEF), and it is used to study the possibility to extract some skin-friction structures from a surface pressure field. This attempt contains two related parts. In the first part, when the BEF field is given, a projected skin-friction field in the image plane can be sought from a surface pressure image based on a variational solution of an optical-flow-like equation. This approach is validated in several classical flows. The second part deals with a practical problem in which the BEF field is not known a priori. In this case, a so-called auxiliary skin-friction field is determined from a surface pressure image alone by using the same variational approach. The auxiliary skin-friction field has the magnitude proportional to the skin-friction magnitude and the direction of the negative surface pressure gradient. The physical meaning of the auxiliary skin-friction field and its applicability to global skin-friction diagnostics are discussed.

Original languageEnglish
Article number125304
JournalMeasurement Science and Technology
Volume27
Issue number12
DOIs
Publication statusPublished - 2016 Oct 28

Keywords

  • boundary enstrophy flux
  • complex flow
  • image measurement
  • inverse problem, optical flow
  • skin friction
  • surface pressure gradient

ASJC Scopus subject areas

  • Instrumentation
  • Engineering (miscellaneous)
  • Applied Mathematics

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