The Experts below are selected from a list of 11622 Experts worldwide ranked by ideXlab platform

Lars C Gansel - One of the best experts on this subject based on the ideXlab platform.

  • OMAE2009-79355 Flow Around the Free Bottom Of Fish Cages In a Uniform Flow With And Without Fouling
    2020
    Co-Authors: Lars C Gansel, Thomas A Mcclimans, Dag Myrhaug
    Abstract:

    ABSTRACT This paper explores the flow around Fish Cages in a uniform flow with the focus on the flow patterns close to the bottom of the models. Towing tests were conducted with six straight cylinders with the porosities 0%, 30%, 60%, 75%, 82% and 90%, two cylinders with an inclination of 12.5 degrees and the porosities 0% and 75% and two cylinders with an inclination of 25 degrees and the porosities 0% and 75%. The models all had a height-to-diameter ratio of 3 and were made from metal mesh. The Reynolds number was 5000 based on the diameter of the models and from 15 to 300 based on the diameter of individual strings of the mesh for all tests. Particle Image Velocimetry (PIV), a non-intrusive optical technique, was used to analyze the flow around the models in the plane of symmetry through the center of the cylinders. The porosities of 82%, 75% and 60% correspond to those of a clean Fish cage netting in Norwegian Salmon farming with no fouling, light fouling and heavy fouling, respectively. The inclinations of 12.5 degrees and 25 degrees reflect the inclination of the net of a commercial Fish cage in a slow and a fast current, respectively. The Reynolds number of the strings was within the range of Reynolds numbers occurring on Fish Cages along the Norwegian coast. The results from this study are discussed with respect to the flow around and through the same models at identical Reynolds numbers. It is shown that the inclination of the net cage and fouling of the netting have major effects on the flow pattern around Fish Cages. The flow around and through net Cages defines the water exchange within Fish Cages and the distribution patterns of particles and nutrients released from a net-pen. The information provided in this study can be valuable for the Fish farming industry, as the decrease of the porosity due to fouling, as well as the deformation of the netting of Fish Cages, can be controlled by Fish farmers

  • effects of a shielding skirt for prevention of sea lice on the flow past stocked salmon Fish Cages
    Journal of Offshore Mechanics and Arctic Engineering-transactions of The Asme, 2015
    Co-Authors: Kevin Frank, Lars C Gansel, Andreas Myskja Lien, Jens Birkevold
    Abstract:

    The effect of a shielding skirt, a tarpaulin mounted from the surface down to 5 meter depth around a net cage, on the flow pattern at a commercially stocked salmon cage was investigated. Dye was used as a tracer for water movement and the dye spreading was monitored using aerial images. Current meters were employed to investigate the flow close to the net inside and outside the cage. Tests were conducted with and without the shielding skirt. The focus was on the effectiveness of the shielding skirt to deflect water around the cage. This study shows that a shielding skirt can reduce horizontal flow components significantly inside a cage, which is related to a reduction of water exchange. The flow towards a cage is divided by a shielding skirt, i.e. some of the water is transported around the cage, while some is passing underneath the shielding skirt. Some water entering the Fish cage from underneath the tarpaulin is transported towards the surface inside the cage. The use of a shielding skirt might not prevent interaction of the upper water layers inside and outside of a Fish cage completely, but it has the potential to reduce the inflow of surface water into the cage, if deployed properly.Copyright © 2013 by ASME

  • hydrodynamic interactions on net panel and aquaculture Fish Cages a review
    Ocean Engineering, 2013
    Co-Authors: Pascal Klebert, Lars C Gansel, Pal Lader, Frode Oppedal
    Abstract:

    Abstract Aquaculture is expanding all over the world. The limitations are mainly related to location, water flow, escapees and Fish health. The present status of flow hydrodynamics within and around sea-Cages is reviewed in this paper, providing a framework for understanding the spatial and temporal variability of key environmental parameters within and outside sea-Cages. The paper presents contemporary experiments on drag forces on net panels, model-scale Cages, the biological effects of Fish, Fish movements and fouling as the major topics. It includes also a presentation of different theoretical studies as an attempt to simulate experiments. The accumulated experimental results are sorted out following a gradually increasing scale from the cruciform as a basic element of a net, via net panels to a net cage with solidity and velocity as the main parameters, while the effect of Fish and fouling are discussed only at the full-scale level. The compilation is important to understand issues related to the design and mechanics of net Cages, taking into account Fish behavior in relation to future engineering development within the field of hydrodynamics in aquaculture cage farming. Improved knowledge of water movement through aquaculture Cages is critical for future development of efficient and sustainable aquaculture, including a shift toward more exposed locations.

  • average flow inside and around Fish Cages with and without fouling in a uniform flow
    Journal of Offshore Mechanics and Arctic Engineering-transactions of The Asme, 2012
    Co-Authors: Lars C Gansel, Thomas A Mcclimans, Dag Myrhaug
    Abstract:

    The average flow field inside and around the bottom of porous cylinders in a uniform flow is explored using particle image velocimetry (PIV). Tests were conducted on six cylinders with porosities of 0%, 30%, 60%, 75%, 82%, and 90% in a flume tank where the flow field inside and around the models is time averaged over 180 s. The models had a height-to-diameter ratio of 3 and were made from metal mesh. The Reynolds numbers ranged from 5000 to 20,000 based on the diameter of the models and from 75 to 300 based on the diameter of individual strands of the mesh, which corresponds to the Reynolds numbers occurring at salmon Fish cage netting used along the Norwegian coast. The porosities of 82%, 75%, and 60% correspond to those of a Fish cage netting in Norwegian salmon farming with no, light, and heavy biofouling, respectively. The results from this study are discussed with respect to the instantaneous flow field in and around the same cylinders at identical Reynolds numbers. The focus is on the effect of porosity on the ventilation inside the Cages and the vertical transports within the near wake. It is shown that heavy fouling of aquacultural netting can lead to internal circulation inside Fish Cages and, therefore, has the potential to dramatically reduce the ventilation of the net pens. The description of the time-averaged flow field inside and around porous cylinders can be used as benchmarks to validate and adjust numerical models of the flow past porous cylinders. The results from this study can also be valuable for the Fish farming industry, since bio-fouling and the reduced porosity ofFish Cages can be monitored and controlled directly by Fish farmers.

  • flow around the free bottom of Fish Cages in a uniform flow with and without fouling
    Journal of Offshore Mechanics and Arctic Engineering-transactions of The Asme, 2012
    Co-Authors: Lars C Gansel, Thomas A Mcclimans, Dag Myrhaug
    Abstract:

    This paper explores the flow around Fish Cages in a uniform flow with the focus on the flow patterns close to the bottom of the models. Towing tests were conducted with six straight cylinders with the porosities 0%, 30%, 60%, 75%, 82%, and 90%, two cylinders with an inclination of 12.5 deg, and the porosities 0% and 75% and two cylinders with an inclination of 25 deg and the porosities 0% and 75%. The models all had a height-to-diameter ratio of 3 and were made from metal mesh. The Reynolds number was 5000 based on the diameter of the models and 15 based on the diameter of individual strings of the mesh for all tests. Particle image velocimetry, a nonintrusive optical technique, was used to analyze the flow around the models in the plane of symmetry through the center of the cylinders. The porosities of 82%, 75%, and 60% correspond to those of a clean Fish cage netting in Norwegian Salmon farming with no fouling, light fouling, and heavy fouling, respectively. The inclinations of 12.5 deg and 25 deg reflect the inclination of the net of a commercial Fish cage in a slow and a fast current, respectively. The Reynolds number of the strings was within the range of Reynolds numbers occurring on Fish Cages along the Norwegian coast. The results from this study are discussed with respect to the flow around and through the same models at identical Reynolds numbers. It is shown that the inclination of the net cage and fouling of the netting have major effects on the flow pattern around Fish Cages. The flow around and through net Cages defines the water exchange within Fish Cages and the distribution patterns of particles and nutrients released from a net-pen. The information provided in this study can be valuable for the Fish farming industry, as the decrease of the porosity due to fouling, as well as the deformation of the netting of Fish Cages, can be controlled by Fish farmers.

Kelasidi Eleni - One of the best experts on this subject based on the ideXlab platform.

  • Underwater Communication and Position Reference System
    SINTEF Ocean AS, 2020
    Co-Authors: Su Biao, Kelasidi Eleni, Thorbjørnsen, Eirik Storås
    Abstract:

    This report presents results obtained in the CageReporter project regarding the development of a low cost hydroacoustic subsea communication system adapted for use in Fish Cages. The report mainly addresses tasks regarding the optimization of sender and receiver technology, as well as algorithms for advanced signal processing to optimize bandwidth while ensuring stable real-time communication during operations in Fish Cages. The solutions have been tested and validated in full scale field trials in two Fish farms. In addition, this activity presents a solution developed to obtain a relative position reference system where the main challenge was to develop a realistic real-time map of the Fish cage. The report describes the analytical study that conducted to place the acoustic transmitters. The proposed configuration has been tested in full scale. Afterwards, the obtained experimental data have been used to develop and validate numerical methods that estimate a high-resolution real-time map of the Fish cage. The work furthermore includes the development of algorithms for state estimation to increase accuracy and reduce target noise. The accuracy of the position reference system has been validated through multiple filed trials.publishedVersio

  • Underwater Communication and Position Reference System
    SINTEF Ocean AS, 2020
    Co-Authors: Su Biao, Kelasidi Eleni, Thorbjørnsen, Eirik Storås
    Abstract:

    This report presents results obtained in the CageReporter project regarding the development of a low cost hydroacoustic subsea communication system adapted for use in Fish Cages. The report mainly addresses tasks regarding the optimization of sender and receiver technology, as well as algorithms for advanced signal processing to optimize bandwidth while ensuring stable real-time communication during operations in Fish Cages. The solutions have been tested and validated in full scale field trials in two Fish farms. In addition, this activity presents a solution developed to obtain a relative position reference system where the main challenge was to develop a realistic real-time map of the Fish cage. The report describes the analytical study that conducted to place the acoustic transmitters. The proposed configuration has been tested in full scale. Afterwards, the obtained experimental data have been used to develop and validate numerical methods that estimate a high-resolution real-time map of the Fish cage. The work furthermore includes the development of algorithms for state estimation to increase accuracy and reduce target noise. The accuracy of the position reference system has been validated through multiple filed trials

  • Underwater Communication and Position Reference System - OC2020 A-034
    SINTEF Ocean AS, 2020
    Co-Authors: Su Biao, Kelasidi Eleni, Thorbjørnsen, Eirik Storås
    Abstract:

    This report presents results obtained in the CageReporter project regarding the development of a low cost hydroacoustic subsea communication system adapted for use in Fish Cages. The report mainly addresses tasks regarding the optimization of sender and receiver technology, as well as algorithms for advanced signal processing to optimize bandwidth while ensuring stable real-time communication during operations in Fish Cages. The solutions have been tested and validated in full scale field trials in two Fish farms. In addition, this activity presents a solution developed to obtain a relative position reference system where the main challenge was to develop a realistic real-time map of the Fish cage. The report describes the analytical study that conducted to place the acoustic transmitters. The proposed configuration has been tested in full scale. Afterwards, the obtained experimental data have been used to develop and validate numerical methods that estimate a high-resolution real-time map of the Fish cage. The work furthermore includes the development of algorithms for state estimation to increase accuracy and reduce target noise. The accuracy of the position reference system has been validated through multiple filed trials

  • CAGEREPORTER - Development of technology for autonomous, bio-interactive and high-quality data acquisition from aquaculture net Cages
    SINTEF Ocean AS, 2020
    Co-Authors: Kelasidi Eleni, Schellewald Christian, Su Biao, Thorbjørnsen, Eirik Storås, Moen Endre, Yip, Mau Hing, Remmen, Bjørnar Moe
    Abstract:

    The CageReporter project adapts the use of autonomous and tetherless underwater vehicles as a carrier of sensor systems for data acquisition, where the data are transferred from sea-based Fish Cages to a centralized land base (Figure 1). The vehicle will use active motion con-trol and acquire data from the cage environment while exploring the Fish Cages. The main project objective is to develop technology for autonomous functionality for adaptive mission planning to achieve high quality data acquisition from the cage space. One of the most im-portant capabilities within this context is to operate in a dynamically changing environment in interaction with the biomass (bio-interactive) and the aquaculture structures. The project addresses many challenges within the aquaculture industry related to poor accuracy and representative sampling of important variables from the whole volume of the cage. A suc-cessful project outcome will lead to new technology for collection of high-resolution data that could be utilized for assessment of the Fish farm state, grouped within three main areas: A) Fish, B) aquaculture structures and C) production environment. Examples of areas of applica-tions are detection of abnormal Fish behaviour, net inspection and mapping of water quality. CageReporter will provide a solution for continuous 24/7 inspection of the current situation and will be the mobile eyes of the Fish farmer in the cage environment. The project idea is based on using low-cost technology for underwater communication, vehicle positioning, and camera systems for 3D vision

  • CAGEREPORTER - Development of technology for autonomous, bio-interactive and high-quality data acquisition from aquaculture net Cages
    SINTEF Ocean AS, 2020
    Co-Authors: Kelasidi Eleni, Schellewald Christian, Su Biao, Thorbjørnsen, Eirik Storås, Moen Endre, Yip, Mau Hing, Remmen, Bjørnar Moe, Mulelid Mats
    Abstract:

    The CageReporter project adapts the use of autonomous and tetherless underwater vehicles as a carrier of sensor systems for data acquisition, where the data are transferred from sea-based Fish Cages to a centralized land base (Figure 1). The vehicle will use active motion con-trol and acquire data from the cage environment while exploring the Fish Cages. The main project objective is to develop technology for autonomous functionality for adaptive mission planning to achieve high quality data acquisition from the cage space. One of the most im-portant capabilities within this context is to operate in a dynamically changing environment in interaction with the biomass (bio-interactive) and the aquaculture structures. The project addresses many challenges within the aquaculture industry related to poor accuracy and representative sampling of important variables from the whole volume of the cage. A suc-cessful project outcome will lead to new technology for collection of high-resolution data that could be utilized for assessment of the Fish farm state, grouped within three main areas: A) Fish, B) aquaculture structures and C) production environment. Examples of areas of applica-tions are detection of abnormal Fish behaviour, net inspection and mapping of water quality. CageReporter will provide a solution for continuous 24/7 inspection of the current situation and will be the mobile eyes of the Fish farmer in the cage environment. The project idea is based on using low-cost technology for underwater communication, vehicle positioning, and camera systems for 3D vision.publishedVersio

Thomas A Mcclimans - One of the best experts on this subject based on the ideXlab platform.

  • OMAE2009-79355 Flow Around the Free Bottom Of Fish Cages In a Uniform Flow With And Without Fouling
    2020
    Co-Authors: Lars C Gansel, Thomas A Mcclimans, Dag Myrhaug
    Abstract:

    ABSTRACT This paper explores the flow around Fish Cages in a uniform flow with the focus on the flow patterns close to the bottom of the models. Towing tests were conducted with six straight cylinders with the porosities 0%, 30%, 60%, 75%, 82% and 90%, two cylinders with an inclination of 12.5 degrees and the porosities 0% and 75% and two cylinders with an inclination of 25 degrees and the porosities 0% and 75%. The models all had a height-to-diameter ratio of 3 and were made from metal mesh. The Reynolds number was 5000 based on the diameter of the models and from 15 to 300 based on the diameter of individual strings of the mesh for all tests. Particle Image Velocimetry (PIV), a non-intrusive optical technique, was used to analyze the flow around the models in the plane of symmetry through the center of the cylinders. The porosities of 82%, 75% and 60% correspond to those of a clean Fish cage netting in Norwegian Salmon farming with no fouling, light fouling and heavy fouling, respectively. The inclinations of 12.5 degrees and 25 degrees reflect the inclination of the net of a commercial Fish cage in a slow and a fast current, respectively. The Reynolds number of the strings was within the range of Reynolds numbers occurring on Fish Cages along the Norwegian coast. The results from this study are discussed with respect to the flow around and through the same models at identical Reynolds numbers. It is shown that the inclination of the net cage and fouling of the netting have major effects on the flow pattern around Fish Cages. The flow around and through net Cages defines the water exchange within Fish Cages and the distribution patterns of particles and nutrients released from a net-pen. The information provided in this study can be valuable for the Fish farming industry, as the decrease of the porosity due to fouling, as well as the deformation of the netting of Fish Cages, can be controlled by Fish farmers

  • average flow inside and around Fish Cages with and without fouling in a uniform flow
    Journal of Offshore Mechanics and Arctic Engineering-transactions of The Asme, 2012
    Co-Authors: Lars C Gansel, Thomas A Mcclimans, Dag Myrhaug
    Abstract:

    The average flow field inside and around the bottom of porous cylinders in a uniform flow is explored using particle image velocimetry (PIV). Tests were conducted on six cylinders with porosities of 0%, 30%, 60%, 75%, 82%, and 90% in a flume tank where the flow field inside and around the models is time averaged over 180 s. The models had a height-to-diameter ratio of 3 and were made from metal mesh. The Reynolds numbers ranged from 5000 to 20,000 based on the diameter of the models and from 75 to 300 based on the diameter of individual strands of the mesh, which corresponds to the Reynolds numbers occurring at salmon Fish cage netting used along the Norwegian coast. The porosities of 82%, 75%, and 60% correspond to those of a Fish cage netting in Norwegian salmon farming with no, light, and heavy biofouling, respectively. The results from this study are discussed with respect to the instantaneous flow field in and around the same cylinders at identical Reynolds numbers. The focus is on the effect of porosity on the ventilation inside the Cages and the vertical transports within the near wake. It is shown that heavy fouling of aquacultural netting can lead to internal circulation inside Fish Cages and, therefore, has the potential to dramatically reduce the ventilation of the net pens. The description of the time-averaged flow field inside and around porous cylinders can be used as benchmarks to validate and adjust numerical models of the flow past porous cylinders. The results from this study can also be valuable for the Fish farming industry, since bio-fouling and the reduced porosity ofFish Cages can be monitored and controlled directly by Fish farmers.

  • flow around the free bottom of Fish Cages in a uniform flow with and without fouling
    Journal of Offshore Mechanics and Arctic Engineering-transactions of The Asme, 2012
    Co-Authors: Lars C Gansel, Thomas A Mcclimans, Dag Myrhaug
    Abstract:

    This paper explores the flow around Fish Cages in a uniform flow with the focus on the flow patterns close to the bottom of the models. Towing tests were conducted with six straight cylinders with the porosities 0%, 30%, 60%, 75%, 82%, and 90%, two cylinders with an inclination of 12.5 deg, and the porosities 0% and 75% and two cylinders with an inclination of 25 deg and the porosities 0% and 75%. The models all had a height-to-diameter ratio of 3 and were made from metal mesh. The Reynolds number was 5000 based on the diameter of the models and 15 based on the diameter of individual strings of the mesh for all tests. Particle image velocimetry, a nonintrusive optical technique, was used to analyze the flow around the models in the plane of symmetry through the center of the cylinders. The porosities of 82%, 75%, and 60% correspond to those of a clean Fish cage netting in Norwegian Salmon farming with no fouling, light fouling, and heavy fouling, respectively. The inclinations of 12.5 deg and 25 deg reflect the inclination of the net of a commercial Fish cage in a slow and a fast current, respectively. The Reynolds number of the strings was within the range of Reynolds numbers occurring on Fish Cages along the Norwegian coast. The results from this study are discussed with respect to the flow around and through the same models at identical Reynolds numbers. It is shown that the inclination of the net cage and fouling of the netting have major effects on the flow pattern around Fish Cages. The flow around and through net Cages defines the water exchange within Fish Cages and the distribution patterns of particles and nutrients released from a net-pen. The information provided in this study can be valuable for the Fish farming industry, as the decrease of the porosity due to fouling, as well as the deformation of the netting of Fish Cages, can be controlled by Fish farmers.

  • the effects of Fish Cages on ambient currents
    Journal of Offshore Mechanics and Arctic Engineering-transactions of The Asme, 2012
    Co-Authors: Lars C Gansel, Thomas A Mcclimans, Dag Myrhaug
    Abstract:

    Experiments were carried out to measure forces on and wake characteristics downstream from Fish Cages. Cylinders made from metal mesh with porosities of 0%, 30%, 60%, 75%, 82%, and 90% were tested in a towing tank. The drag force was measured with strain gauges, and the flow field downstream from the models was analyzed using particle image velocimetry. The Reynolds numbers ranged from 1000–20,000 based on the model diameter and 15–300 based on the diameter of the strings of the mesh as an independent obstacle. High porosities (here, 82% and 90%) lead to low water blockage and allow a substantial amount of water to flow through the model. The data indicate that the wake characteristics change toward the wake characteristics of a solid cylinder at a porosity just below 75%. The drag force is highly dependent on the porosity for high porosities of a cylinder.

  • flow fields inside stocked Fish Cages and the near environment
    ASME 2011 30th International Conference on Ocean Offshore and Arctic Engineering, 2011
    Co-Authors: Lars C Gansel, Siri Rackebrandt, Frode Oppedal, Thomas A Mcclimans
    Abstract:

    This study explores the average flow field inside and around stocked Atlantic salmon (Salmo salar L.) Fish Cages. Laboratory tests and field measurements were conducted to study the effects of biofouling and especially Fish behaviour on the flow patterns around and through Fish Cages. Currents were measured around an empty and a stocked Fish cage in a fjord to verify the results obtained from laboratory tests without Fish and to study the effects of Fish swimming in the cage. Fluorescein, a non-toxic, fluorescent dye, was released inside a stocked Fish cage for visualization of 3-dimensional flow patterns inside the cage. Atlantic salmon tend to form a torus shaped school and swim in a circular path, following the net during the daytime. Current measurements around an empty and a stocked Fish cage show a strong influence of Fish swimming in this circular pattern: while most of the oncoming water mass passes through the empty cage, significantly more water is pushed around the stocked Fish cage. Dye experiments show that surface water inside stocked Fish Cages converges towards the center, where it sinks and spreads out of the cage at the depth of maximum biomass. Furthermore, the converging surface water swirled in the direction of the swimming Fish. In order to achieve a circular motion, Fish must accelerate towards the center of the cage. This inward-directed force must be balanced by an outward force that pushes the water out of the cage, resulting in a low pressure area in the center of the rotational motion of the Fish. Thus, water is pulled from above and below the Fish swimming depth. The laboratory tests with empty Cages agree well with field measurements around empty Fish Cages, and give a good starting point for further laboratory tests including the effect of Fish-induced currents inside the cage to document the details of the flow patterns inside and adjacent to stocked Fish Cages. The results of such experiments can be used as benchmarks for numerical models to simulate the water flow in and around net pens, and model the oxygen supply and the spreading of wastes in the near wake of stocked Fish farms.Copyright © 2011 by ASME

Remmen, Bjørnar Moe - One of the best experts on this subject based on the ideXlab platform.

  • CAGEREPORTER - Development of technology for autonomous, bio-interactive and high-quality data acquisition from aquaculture net Cages
    SINTEF Ocean AS, 2020
    Co-Authors: Kelasidi Eleni, Schellewald Christian, Su Biao, Thorbjørnsen, Eirik Storås, Moen Endre, Yip, Mau Hing, Remmen, Bjørnar Moe
    Abstract:

    The CageReporter project adapts the use of autonomous and tetherless underwater vehicles as a carrier of sensor systems for data acquisition, where the data are transferred from sea-based Fish Cages to a centralized land base (Figure 1). The vehicle will use active motion con-trol and acquire data from the cage environment while exploring the Fish Cages. The main project objective is to develop technology for autonomous functionality for adaptive mission planning to achieve high quality data acquisition from the cage space. One of the most im-portant capabilities within this context is to operate in a dynamically changing environment in interaction with the biomass (bio-interactive) and the aquaculture structures. The project addresses many challenges within the aquaculture industry related to poor accuracy and representative sampling of important variables from the whole volume of the cage. A suc-cessful project outcome will lead to new technology for collection of high-resolution data that could be utilized for assessment of the Fish farm state, grouped within three main areas: A) Fish, B) aquaculture structures and C) production environment. Examples of areas of applica-tions are detection of abnormal Fish behaviour, net inspection and mapping of water quality. CageReporter will provide a solution for continuous 24/7 inspection of the current situation and will be the mobile eyes of the Fish farmer in the cage environment. The project idea is based on using low-cost technology for underwater communication, vehicle positioning, and camera systems for 3D vision

  • CAGEREPORTER - Development of technology for autonomous, bio-interactive and high-quality data acquisition from aquaculture net Cages
    SINTEF Ocean AS, 2020
    Co-Authors: Kelasidi Eleni, Schellewald Christian, Su Biao, Thorbjørnsen, Eirik Storås, Moen Endre, Yip, Mau Hing, Remmen, Bjørnar Moe, Mulelid Mats
    Abstract:

    The CageReporter project adapts the use of autonomous and tetherless underwater vehicles as a carrier of sensor systems for data acquisition, where the data are transferred from sea-based Fish Cages to a centralized land base (Figure 1). The vehicle will use active motion con-trol and acquire data from the cage environment while exploring the Fish Cages. The main project objective is to develop technology for autonomous functionality for adaptive mission planning to achieve high quality data acquisition from the cage space. One of the most im-portant capabilities within this context is to operate in a dynamically changing environment in interaction with the biomass (bio-interactive) and the aquaculture structures. The project addresses many challenges within the aquaculture industry related to poor accuracy and representative sampling of important variables from the whole volume of the cage. A suc-cessful project outcome will lead to new technology for collection of high-resolution data that could be utilized for assessment of the Fish farm state, grouped within three main areas: A) Fish, B) aquaculture structures and C) production environment. Examples of areas of applica-tions are detection of abnormal Fish behaviour, net inspection and mapping of water quality. CageReporter will provide a solution for continuous 24/7 inspection of the current situation and will be the mobile eyes of the Fish farmer in the cage environment. The project idea is based on using low-cost technology for underwater communication, vehicle positioning, and camera systems for 3D vision.publishedVersio

  • Data capture and real-time data quality analysis
    SINTEF Ocean AS, 2020
    Co-Authors: Kelasidi Eleni, Schellewald Christian, Yip Mauhing, Remmen, Bjørnar Moe
    Abstract:

    This report presents results obtained in the CageReporter project regarding the development of a 3D vision system to be used for data capture in Fish Cages. The developed system enables to obtain high-quality data with the overall goal to identify Fish conditions and perform cage inspections during daily operations, as well as the robotic vision for an underwater vehicle during the adaptive operation planning in the cage. A compact and robust sensor with optical components and lighting system was developed. In addition, this activity presents development of methods to evaluate the quality of the captured data. Based on defined quality criteria associated with Fish conditions and cage inspection operations, algorithms have been developed to evaluate whether the quality criteria are met. The algorithms have been validated using image data obtained from 24/7 video streams from a full-scale Fish cage. The work furthermore includes the development of image processing algorithms to estimate the distance and orientation relative to the inspected object of interest, such as the Fish or the net. The developed algorithms have been validated based on vision data obtained during tests both in lab- and full scale

  • Data capture and real-time data quality analysis
    SINTEF Ocean AS, 2020
    Co-Authors: Kelasidi Eleni, Schellewald Christian, Yip Mauhing, Remmen, Bjørnar Moe
    Abstract:

    This report presents results obtained in the CageReporter project regarding the development of a 3D vision system to be used for data capture in Fish Cages. The developed system enables to obtain high-quality data with the overall goal to identify Fish conditions and perform cage inspections during daily operations, as well as the robotic vision for an underwater vehicle during the adaptive operation planning in the cage. A compact and robust sensor with optical components and lighting system was developed. In addition, this activity presents development of methods to evaluate the quality of the captured data. Based on defined quality criteria associated with Fish conditions and cage inspection operations, algorithms have been developed to evaluate whether the quality criteria are met. The algorithms have been validated using image data obtained from 24/7 video streams from a full-scale Fish cage. The work furthermore includes the development of image processing algorithms to estimate the distance and orientation relative to the inspected object of interest, such as the Fish or the net. The developed algorithms have been validated based on vision data obtained during tests both in lab- and full scale.publishedVersio

Dag Myrhaug - One of the best experts on this subject based on the ideXlab platform.

  • OMAE2009-79355 Flow Around the Free Bottom Of Fish Cages In a Uniform Flow With And Without Fouling
    2020
    Co-Authors: Lars C Gansel, Thomas A Mcclimans, Dag Myrhaug
    Abstract:

    ABSTRACT This paper explores the flow around Fish Cages in a uniform flow with the focus on the flow patterns close to the bottom of the models. Towing tests were conducted with six straight cylinders with the porosities 0%, 30%, 60%, 75%, 82% and 90%, two cylinders with an inclination of 12.5 degrees and the porosities 0% and 75% and two cylinders with an inclination of 25 degrees and the porosities 0% and 75%. The models all had a height-to-diameter ratio of 3 and were made from metal mesh. The Reynolds number was 5000 based on the diameter of the models and from 15 to 300 based on the diameter of individual strings of the mesh for all tests. Particle Image Velocimetry (PIV), a non-intrusive optical technique, was used to analyze the flow around the models in the plane of symmetry through the center of the cylinders. The porosities of 82%, 75% and 60% correspond to those of a clean Fish cage netting in Norwegian Salmon farming with no fouling, light fouling and heavy fouling, respectively. The inclinations of 12.5 degrees and 25 degrees reflect the inclination of the net of a commercial Fish cage in a slow and a fast current, respectively. The Reynolds number of the strings was within the range of Reynolds numbers occurring on Fish Cages along the Norwegian coast. The results from this study are discussed with respect to the flow around and through the same models at identical Reynolds numbers. It is shown that the inclination of the net cage and fouling of the netting have major effects on the flow pattern around Fish Cages. The flow around and through net Cages defines the water exchange within Fish Cages and the distribution patterns of particles and nutrients released from a net-pen. The information provided in this study can be valuable for the Fish farming industry, as the decrease of the porosity due to fouling, as well as the deformation of the netting of Fish Cages, can be controlled by Fish farmers

  • average flow inside and around Fish Cages with and without fouling in a uniform flow
    Journal of Offshore Mechanics and Arctic Engineering-transactions of The Asme, 2012
    Co-Authors: Lars C Gansel, Thomas A Mcclimans, Dag Myrhaug
    Abstract:

    The average flow field inside and around the bottom of porous cylinders in a uniform flow is explored using particle image velocimetry (PIV). Tests were conducted on six cylinders with porosities of 0%, 30%, 60%, 75%, 82%, and 90% in a flume tank where the flow field inside and around the models is time averaged over 180 s. The models had a height-to-diameter ratio of 3 and were made from metal mesh. The Reynolds numbers ranged from 5000 to 20,000 based on the diameter of the models and from 75 to 300 based on the diameter of individual strands of the mesh, which corresponds to the Reynolds numbers occurring at salmon Fish cage netting used along the Norwegian coast. The porosities of 82%, 75%, and 60% correspond to those of a Fish cage netting in Norwegian salmon farming with no, light, and heavy biofouling, respectively. The results from this study are discussed with respect to the instantaneous flow field in and around the same cylinders at identical Reynolds numbers. The focus is on the effect of porosity on the ventilation inside the Cages and the vertical transports within the near wake. It is shown that heavy fouling of aquacultural netting can lead to internal circulation inside Fish Cages and, therefore, has the potential to dramatically reduce the ventilation of the net pens. The description of the time-averaged flow field inside and around porous cylinders can be used as benchmarks to validate and adjust numerical models of the flow past porous cylinders. The results from this study can also be valuable for the Fish farming industry, since bio-fouling and the reduced porosity ofFish Cages can be monitored and controlled directly by Fish farmers.

  • flow around the free bottom of Fish Cages in a uniform flow with and without fouling
    Journal of Offshore Mechanics and Arctic Engineering-transactions of The Asme, 2012
    Co-Authors: Lars C Gansel, Thomas A Mcclimans, Dag Myrhaug
    Abstract:

    This paper explores the flow around Fish Cages in a uniform flow with the focus on the flow patterns close to the bottom of the models. Towing tests were conducted with six straight cylinders with the porosities 0%, 30%, 60%, 75%, 82%, and 90%, two cylinders with an inclination of 12.5 deg, and the porosities 0% and 75% and two cylinders with an inclination of 25 deg and the porosities 0% and 75%. The models all had a height-to-diameter ratio of 3 and were made from metal mesh. The Reynolds number was 5000 based on the diameter of the models and 15 based on the diameter of individual strings of the mesh for all tests. Particle image velocimetry, a nonintrusive optical technique, was used to analyze the flow around the models in the plane of symmetry through the center of the cylinders. The porosities of 82%, 75%, and 60% correspond to those of a clean Fish cage netting in Norwegian Salmon farming with no fouling, light fouling, and heavy fouling, respectively. The inclinations of 12.5 deg and 25 deg reflect the inclination of the net of a commercial Fish cage in a slow and a fast current, respectively. The Reynolds number of the strings was within the range of Reynolds numbers occurring on Fish Cages along the Norwegian coast. The results from this study are discussed with respect to the flow around and through the same models at identical Reynolds numbers. It is shown that the inclination of the net cage and fouling of the netting have major effects on the flow pattern around Fish Cages. The flow around and through net Cages defines the water exchange within Fish Cages and the distribution patterns of particles and nutrients released from a net-pen. The information provided in this study can be valuable for the Fish farming industry, as the decrease of the porosity due to fouling, as well as the deformation of the netting of Fish Cages, can be controlled by Fish farmers.

  • the effects of Fish Cages on ambient currents
    Journal of Offshore Mechanics and Arctic Engineering-transactions of The Asme, 2012
    Co-Authors: Lars C Gansel, Thomas A Mcclimans, Dag Myrhaug
    Abstract:

    Experiments were carried out to measure forces on and wake characteristics downstream from Fish Cages. Cylinders made from metal mesh with porosities of 0%, 30%, 60%, 75%, 82%, and 90% were tested in a towing tank. The drag force was measured with strain gauges, and the flow field downstream from the models was analyzed using particle image velocimetry. The Reynolds numbers ranged from 1000–20,000 based on the model diameter and 15–300 based on the diameter of the strings of the mesh as an independent obstacle. High porosities (here, 82% and 90%) lead to low water blockage and allow a substantial amount of water to flow through the model. The data indicate that the wake characteristics change toward the wake characteristics of a solid cylinder at a porosity just below 75%. The drag force is highly dependent on the porosity for high porosities of a cylinder.

  • average flow inside and around Fish Cages with and without fouling in a uniform flow
    ASME 2010 29th International Conference on Ocean Offshore and Arctic Engineering, 2010
    Co-Authors: Lars C Gansel, Thomas A Mcclimans, Dag Myrhaug
    Abstract:

    The average flow field inside and around the bottom of porous cylinders in a uniform flow is explored using Particle Image Velocimetry (PIV). Tests were conducted on six cylinders with porosities of 0%, 30%, 60%, 75%, 82% and 90% in a flume tank where the flow field inside and around the models is time averaged over 180 seconds. The models had a height-to-diameter ratio of 3 and were made from metal mesh. The Reynolds numbers ranged from 5,000 to 20,000 based on the diameter of the models and from 75 to 300 based on the diameter of individual strands of the mesh, which corresponds to the Reynolds numbers occurring at salmon Fish cage netting used along the Norwegian coast. The porosities of 82%, 75% and 60% correspond to those of a Fish cage netting in Norwegian Salmon farming with no, light and heavy biofouling, respectively. The results from this study are discussed with respect to the instantaneous flow field in and around the same cylinders at identical Reynolds numbers. The focus is on the effect of porosity on the ventilation inside the Cages and the vertical transports within the near wake. It is shown that heavy fouling of aquacultural nettings can lead to internal circulation inside Fish Cages and therefore has the potential to reduce the ventilation of the net pens dramatically. The description of the time-averaged flow field inside and around porous cylinders can be used as benchmarks to validate and adjust numerical models of the flow past porous cylinders. The results from this study can be valuable also for the Fish farming industry, as bio-fouling and the reduced porosity of Fish Cages can be monitored and controlled directly by Fish farmers.© 2010 ASME