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Open AccessArticle

Dynamically Scaled Model Experiment of a Mooring Cable

by Lars Bergdahl 1,*, Johannes Palm 1,†, Claes Eskilsson 1,† and Jan Lindahl 2,†
1
Division of Marine Technology, Department of Shipping and Marine Technology, Chalmers, Göteborg SE-412 96, Sweden
2
Department of Hydraulics, School of Civil Engineering, Chalmers, Göteborg SE-412 96, Sweden
*
Author to whom correspondence should be addressed.
These authors contributed equally to this work.
Academic Editor: Raúl Guanche García
J. Mar. Sci. Eng. 2016, 4(1), 5; https://doi.org/10.3390/jmse4010005
Received: 23 November 2015 / Revised: 28 December 2015 / Accepted: 15 January 2016 / Published: 25 January 2016
(This article belongs to the Special Issue Ocean Wave Energy Conversion)
The dynamic response of mooring cables for marine structures is scale-dependent, and perfect dynamic similitude between full-scale prototypes and small-scale physical model tests is difficult to achieve. The best possible scaling is here sought by means of a specific set of dimensionless parameters, and the model accuracy is also evaluated by two alternative sets of dimensionless parameters. A special feature of the presented experiment is that a chain was scaled to have correct propagation celerity for longitudinal elastic waves, thus providing perfect geometrical and dynamic scaling in vacuum, which is unique. The scaling error due to incorrect Reynolds number seemed to be of minor importance. The 33 m experimental chain could then be considered a scaled 76 mm stud chain with the length 1240 m, i.e., at the length scale of 1:37.6. Due to the correct elastic scale, the physical model was able to reproduce the effect of snatch loads giving rise to tensional shock waves propagating along the cable. The results from the experiment were used to validate the newly developed cable-dynamics code, MooDy, which utilises a discontinuous Galerkin FEM formulation. The validation of MooDy proved to be successful for the presented experiments. The experimental data is made available here for validation of other numerical codes by publishing digitised time series of two of the experiments. View Full-Text
Keywords: mooring cable; dynamic model test; scaling laws; numerical validation mooring cable; dynamic model test; scaling laws; numerical validation
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MDPI and ACS Style

Bergdahl, L.; Palm, J.; Eskilsson, C.; Lindahl, J. Dynamically Scaled Model Experiment of a Mooring Cable. J. Mar. Sci. Eng. 2016, 4, 5.

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