Thumbnail
Access Restriction
Subscribed

Author Lader, Pål ♦ Fredriksson, David W. ♦ Guenther, Jana ♦ Volent, Zsolt ♦ Blocher, Nina ♦ Kristiansen, David ♦ Gansel, Lars ♦ Decew, Jud
Source SpringerLink
Content type Text
Publisher Chinese Ocean Engineering Society
File Format PDF
Copyright Year ©2015
Language English
Subject Domain (in DDC) Technology ♦ Engineering & allied operations
Subject Keyword hydroid ♦ biofouling ♦ aquaculture net ♦ hydrodynamic drag ♦ Offshore Engineering ♦ Oceanography ♦ Coastal Sciences ♦ Fluid- and Aerodynamics ♦ Marine & Freshwater Sciences ♦ Numerical and Computational Physics
Abstract The present study investigated the drag increase on aquaculture nets due to biofouling of the colonial hydroid Ectopleura larynx. It had two main parts: firstly the growth characteristics of E. larynx were investigated by use of field tests at a Norwegian aquaculture site; secondly the hydrodynamic drag on the fouled twines was studied in a towing tank by using fabricated models of net twines with artificial hydroid fouling. In the field tests, the growth of the hydroids was first measured after three weeks of immersion and then again after six weeks. During this interval, the density of hydroids and the thickness of the hydroid stem were almost constant (1.4 hydroids/mm and 0.29 mm, respectively), while the average length of the hydroids increased from 6.4 to 11.2 mm. The hydroid length followed a Rayleigh distribution, while the thickness was normal (Gaussian) distributed. Replicas of twines with three different levels of hydroid growth were made (1.5 hydroids/mm twine, hydroid length 9 mm, 16 mm and 20 mm), and the drag on these twines was measured at different towing velocities (0.1 to 1.4 m/s) and with different twine configurations. For the twine with the shortest hydroids (9 mm), the drag was from 1.5 times (Re=4000) to 2.2 times (Re=1000) the drag on a clean twine. For the longest hydroids (21 mm), the drag was 2 times and 3.8 times, respectively.
ISSN 08905487
Age Range 18 to 22 years ♦ above 22 year
Educational Use Research
Education Level UG and PG
Learning Resource Type Article
Publisher Date 2015-06-04
Publisher Place Nanjing
e-ISSN 21918945
Journal China Ocean Engineering
Volume Number 29
Issue Number 3
Page Count 21
Starting Page 369
Ending Page 389


Open content in new tab

   Open content in new tab
Source: SpringerLink