Drag on Hydroid-Fouled Nets – An Experimental Approach

作     者：Pl LADER David W. FREDRIKSSON Jana GUENTHER Zsolt VOLENT Nina BLOCHER David KRISTIANSEN Lars GANSEL Jud DECEW 

作者机构：SINTEF Fisheries and Aquaculture United States Naval Academy University of New Hampshire 

出 版 物：《China Ocean Engineering》 (中国海洋工程（英文版）)

年 卷 期：2015年第29卷第3期

页      面：369-389页

核心收录：

学科分类：0710[理学-生物学] 090801[农学-水产养殖] 0830[工学-环境科学与工程（可授工学、理学、农学学位）] 0908[农学-水产] 0707[理学-海洋科学] 0807[工学-动力工程及工程热物理] 09[农学] 0815[工学-水利工程] 0824[工学-船舶与海洋工程] 0802[工学-机械工程] 0801[工学-力学（可授工学、理学学位）] 

基　　金：fanatically supported by the Norwegian Research Council through the project Hydroids on aquaculture constructions in Norway(190463/S40) the CREATE Centre for Aquaculture Technology 

主　　题：hydroid biofouling aquaculture net hydrodynamic drag 

摘      要：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.