Mechanical Engineering - Research Publications

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The effect of cleaning and repainting on the ship drag penalty

Utama, IKAP ; Nugroho, B ; Yusuf, M ; Prasetyo, FA ; Hakim, ML ; Suastika, IK ; Ganapathisubramani, B ; Hutchins, N ; Monty, JP (TAYLOR & FRANCIS LTD, 2021-07-01)

Although the hull of a recently dry-docked large ship is expected to be relatively smooth, surface scanning and experimentation reveal that it can exhibit an "orange-peel" roughness pattern with an equivalent sand-grain roughness height ks = 0. 101 mm. Using the known ks value and integral boundary layer evolution, a recently cleaned and coated full-scale ship was predicted to experience a significant increase in the average coefficient of friction %ΔC¯f and total hydrodynamic resistance %ΔR¯T during operation. Here the report also discusses two recently reported empirical estimations that can estimate ks directly from measured surface topographical parameters, by-passing the need for experiments on replicated surfaces. The empirical estimations are found to have an accuracy of 4.5 - 5 percentage points in %ΔC¯f.
Non-k-type behaviour of roughness when in-plane wavelength approaches the boundary layer thickness

Nugroho, B ; Monty, JP ; Utama, IKAP ; Ganapathisubramani, B ; Hutchins, N (CAMBRIDGE UNIV PRESS, 2021-01-22)

Abstract
The Effects of Anisotropic Surface Roughness on Turbulent Boundary-Layer Flow

Ramani, A ; Nugroho, B ; Busse, A ; Monty, JP ; Hutchins, N ; Jelly, TO (The University of Queensland, 2020-01-01)