Browsing NTNU Open by Author "Sævik, Svein"
Now showing items 1-20 of 145
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A numerical study on vortex-induced vibrations and the effect of slurry density variations on fatigue of ocean mining risers
Thorsen, Mats Jørgen; Challabotla, Niranjan Reddy; Sævik, Svein; Nydal, Ole Jørgen (Journal article; Peer reviewed, 2019)Ocean mining emerges as a way of meeting future demands for valuable minerals. Risers conveying ore from the seabed to the surface must withstand large wave and current loads. In addition, vortex-induced vibrations (VIV) ... -
Adaptive identification of lowpass filter cutoff frequency for online vessel model tuning
Han, Xu; Ren, Zhengru; Leira, Bernt Johan; Sævik, Svein (Peer reviewed; Journal article, 2021)Tuning of vessel models in real-time based on vessel measurements and weather information is of great interest in order to increase the safety and efficiency of marine operations. Vessel motion signals usually contain ... -
Advances in semi-empirical time domain modelling of vortex-induced vibrations
Ulveseter, Jan Vidar (Doctoral theses at NTNU;2018:135, Doctoral thesis, 2018)Most of today’s prediction tools for vortex-induced vibrations (VIV) operate in the frequency domain, where analysis is restricted to linear systems and steady flows. These modelling limitations provide an unsatisfactory ... -
Algorithmic formulation of clay and sand pipe–soil interaction models for on-bottom stability analysis
Longva, Vegard; Ji, Guomin; Sævik, Svein; Ye, Naiquan; Gjøsteen, Janne Kristin Økland; Giertsen, Egil; Wang, Yanbin (Peer reviewed; Journal article, 2021)This paper presents a new algorithmic formulation of the clay and sand pipe–soil interaction models recommended by the DNV-RP-F109 code for dynamic on-bottom stability analysis of submarine pipelines. The pipe–soil force ... -
An Analytical Model of the Effect of Internal Density Waves in Risers Subjected to Vortex Shedding
Thorsen, Mats Jørgen; Sævik, Svein (Chapter, 2018)Risers used for deep sea mining will be subjected to vortex-induced vibrations (VIV) caused by ocean currents. The internal flow, consisting of e.g. mineral ore and water, will have a non-uniform density. This traveling ... -
An Analytical Treatment of Buckling and Instability of Tensile Armors in Flexible Pipes
Sævik, Svein; Thorsen, Mats Jørgen (Journal article; Peer reviewed, 2017)The present paper addresses aspects related to local buckling and instability of tensile armors in flexible pipes. Analytical models for evaluating the tensile armor buckling capacity in both transverse (radial and lateral) ... -
An Analytical Treatment of Buckling and Instability of Tensile Armors in Flexible Pipes
Sævik, Svein; Thorsen, Mats Jørgen (Journal article; Peer reviewed, 2017)The present paper addresses aspects related to local buckling and instability of tensile armors in flexible pipes. Analytical models for evaluating the tensile armor buckling capacity in both transverse (radial and lateral) ... -
An anisotropic friction model in non-bonded flexible risers
Dai, Tianjiao; Sævik, Svein; Ye, Naiquan (Journal article; Peer reviewed, 2018)The present paper addresses small scale friction tests and an anisotropic friction model to predict friction for the interface between the anti-wear tape and tensile armors in non-bonded flexible risers. Small scale friction ... -
Analysis and control of drilling riser dynamics in dual gradient drilling
Fossum, Trygve Olav (Master thesis, 2013)The aim of this thesis is to investigate a dual gradient riser system, adapted for operations in the Gulf of Mexico and subjected to first- and second-order wave forces, current and rig/vessel motion.Deep water drilling ... -
Analysis of full-scale riser responses in field conditions based on Gaussian mixture model
Wu, Jie; Eidnes, Sølve; Jin, Jingzhe; Lie, Halvor; Yin, Decao; Passano, Elizabeth Anne; Sævik, Svein; Riemer-Sørensen, Signe (Peer reviewed; Journal article, 2022)Offshore slender marine structures experience complex and combined load conditions from waves, current and vessel motions that may result in both wave frequency and vortex shedding response patterns. Field measurements ... -
Analysis of ROV Lift Operation
Bjerkholt, Runa Folvik (Master thesis, 2014)As a service company performing subsea operations, DeepOcean wishes to operate in the widest range of sea conditions. The majority of all offshore operations are performed using remotely operated vehicles (ROVs), where ... -
Analysis of the FlipCage aquaculture concept
Solheim, Inga Lindemark (Master thesis, 2019)Fiskeoppdrett har vært en industri i enorm utvikling de siste årene, men med denne utviklingen har det også dukket opp en rekke utfordringer knyttet til fiskelus, forurensning og mangel på lokasjoner. Fiskeridirektoratet ... -
Analyzing the Sensitivity of Wave Frequency Responses of Floating Vessels to Uncertain System Variables Utilizing Polynomial Chaos Expansion
Radhakrishnan, Gowtham; Leira, Bernt Johan; Gao, Zhen; Sævik, Svein; Han, Xu (Peer reviewed; Journal article, 2023)From a mathematical viewpoint, the frequency domain analysis of vessel motion responses due to wave actions is based on integration of system dynamics idealized in terms of response amplitude operators for six degrees-of-freedom ... -
Anchor Hooking of Pipelines
Dai, Tianjiao (Master thesis, 2013)1.Pipeline material effectThe displacement and force of mid-element pipeline in local horizontal and verticalplane in the elastoplastic pipeline model are larger than that in the elastic model.In the opposite way the bending ... -
Anchor Loads on Pipelines
Wei, Ying (Master thesis, 2015)Anchor hooking on a subsea pipeline has been investigated in this thesis. Anchor loads on pipelines is in general a rarely occurring event, however, the severity when it occurs could easily jeopardize the integrity of any ... -
Assessment of Marine Riser Joints During Offshore Drilling Operation
Bay, Martine Gripp (Master thesis, 2016)Riser technology is pushed to its limits as the demand for deeper drilling operations increases. There exist no standards for the mechanical assessment of marine riser joints today, however new standards are under development ... -
Assessment of VIV fatigue of subsea template jumper by using a time domain model
Sieber, L.; Sævik, Svein; Ringsberg, J. W.; Liu, Zhenhui (Chapter, 2021)This paper addresses the application of a time domain model for Vortex-Induced Vibration (VIV) to assess the fatigue damage of subsea jumpers. The time domain model, capable of accounting for structural non-linearity and ... -
Assessment on the potential use of vessel motion limit criteria for subsea cable installation
Lammers, Anneli (Master thesis, 2020) -
Clump-weight trawl gear interaction with submarine pipelines
Johnsen, Ingrid Berg (Master thesis, 2012)Clump weights come in several shapes, with a mass generally between 2 to 9 tons [5]. With extensive oshore development in the last decades, vast networks of pipelines are installed on the sea bottom. With both pipeline ... -
Clump-weight Trawl Gear Interaction with Submarine Pipelines
Maalø, Kristian (Master thesis, 2011)A recent development in bottom trawling is the use of twin trawl equipment, where two trawl nets are towed side by side from a single vessel. This increases the catch rate and efficiently of the trawler. Governed by cost ...