Numerical investigation of a new micro-patterned surface inspired by shark skin

Student thesis: Doctoral Thesis

Abstract

Concerning the environmental challenge caused by the shipping industry, particularly diesel exhaust and toxic biocide-based anti-fouling system, the author proposed a new micro-patterned surface as a promising ship coating system, which is inspired by the shark skin surface. The new surface pattern combines the core working pattern of two existing surface technologies: Riblet and Sharklet AF™, and is expected to possess both drag-reduction and anti-fouling performance.Computational Fluid Dynamics (CFD) is employed as the main approach in this work to examine the drag-reduction performance of the new surface pattern. The RANS engineering turbulence model, Realizable K-Epsilon Two-Layer (RKE 2L), is used by the author to simulate the new design surface in the turbulent channel flow. The specific RKE 2L turbulence model is firstly used for the drag-reduction investigation of the riblet surface and is validated by a case study of symmetric v-groove riblet surface.The drag-reduction performance of the new surface pattern is directly justified by comparing the skin friction of new surface and reference smooth surface, and indirectly justified by observing the upwards velocity shift in the log layer. Finally, a parametric study is conducted for the new surface pattern to explore the drag-reduction mechanism and the optimization direction.To understand the riblet coating's practical impact on the full-scale ship, the similarity law scaling method is adjusted and written into the in-house code to extend the drag-reduction results from channel flow scale to full ship length scale. Moreover, a three-step procedure is proposed by the author to provide naval architects a guidance to derive the suitable riblet coating size where maximum riblet drag-reduction performance can be achieved in the most of voyage time. Finally, five real-world case ship types and relevant speed distribution are considered to predict the riblet coating's impact, which is quantified by the drag-reduction percentage and fuel savings.The author believes that the shark skin inspired micro-patterned surface would pave a basement for the road to new innovative energy efficient approaches for the shipping industry.
Date of Award1 Oct 2017
LanguageEnglish
Awarding Institution
  • University Of Strathclyde
SponsorsUniversity of Strathclyde
SupervisorOsman Turan (Supervisor) & Qing Xiao (Supervisor)

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