Session: 06-09-01 Offshore Industry: Aquaculture, Mining, etc. I

Paper Number: 124350

124350 - An Ecology Friendly, Closed-Cage Fish Farm. Computational Model Validation Against Results From Field Measurements 

A closed-cage fish farm was built at a relatively sheltered location in northern Norway.
The closed-cage solution is more ecology friendly than the frequently used net-cage fish farms,
since the fish breeding water is separated from the outside ocean space, thus preventing entry of
the parasitic sea lice. Moreover, the fish food, waste, applied chemicals and medicines are
under control and do not contaminate the outside sea water.

The fish farm structure was designed according to the obligatory regulations, to be sound mechanically
under local environmental loads occurring at the installation site. To further verify initial
estimates of the environmental loads due to current and waves, two sensors that measure vertical current
speed profile and directional wave parameters were placed in the fish farm neighbourhood.

The structural response was measured as well. Sensors that recorded forces in mooring lines,
internal structural forces and motions (accelerations) of the fish farm moving components were placed
at optimal locations on the structure.

The measurement campaign lasted for one year, thus covering all weather seasons. The acquired large data sets
were analysed statistically, but also an effort was made to find individual extreme environmental load
occurrences. It is underlined that the measurements were made in full scale conditions (geometry and
environment), and not on the geometrically scaled model as in a laboratory or experimental tank.

A detailed hydromechanical model of the fish farm was created. Numerical calculations of the structure's
response were performed with the popular OrcaFlex software. The detected individual extreme environmental
load events were reproduced numerically, and the corresponding structural response was simulated in time
domain. A comparison of the field-measured data with the computational results is presented in the paper,
followed by a discussion and conclusions.

Presenting Author: Bogdan Iwanowski Semar AS

Presenting Author Biography: Educated as Naval Architect, at Technical University of Szczecin, Poland, M.Sc. in 1987.
Obtained title Doctor of Engineering in fluid-structure interaction at Hiroshima University, Japan, Ph.D in 1993.
Worked several years at Universities before moving to oil and gas industry.
Work experience of 30+ years, with projects in structural mechanics, hydrodynamics, CFD,
fluid-structure interaction, marine operations and other.
Employed at FORCE Technology Norway for 25+ years before moving to Semar AS in 2023.

Authors:

Bogdan Iwanowski Semar AS
Jim-Roger Myrholt Akvafuture AS
Glenn Ovesen Akvafuture AS
Finn-Christian Hanssen Semar AS
Annette Kristin Brask Semar AS
Adil Latif Semar AS