Prosjekt masteroppgaver innen marin byggteknikk … Evaluation of ... gantry (RMG)) that allows the...

Marin byggteknikk – Prosjekt og masteroppgaver 2013/2014 – Studieretning K og BA

Marine Civil Engineering – Project and Master Theses suggestions - 2013/2014

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Liste over oppgaver følger nedenfor. List of suggested topics follow below

Prosjekt masteroppgaver innen marin byggteknikk 2013/2014 Hei Denne oversikten gjelder for studenter som vurderer fordypning inn mot feltene som tilbys av Faggruppe marin byggteknikk på BAT. De fleste oppgavene er beskrevet på engelsk siden vi har mange utenlandske studenter som er interessert i oppgaver hos Faggruppe marin byggteknikk tilbyr primært fordypning inn mot studieretning konstruksjon, men tilbyr også fordypning som passer studenter med bygg og anleggsteknisk bakgrunn. Denne listen over aktuelle Prosjekt/masteropgaver innen Marin byggteknikk finner dere på http://www.ntnu.no/bat/studier/oppgaver. Orientering om hvordan du skal velge prosjektoppgave og fordypning om du er på studieretninger ved BAT står på samme side. Om du tilhører studieretning Konstruksjon følger du opplegget der og angir koden ”9.x.y tittel” for oppgaven, men ta kontakt med ansvarlig faglærer i god tid før 15. mai. Opplegg for registrering for studieretning konstruksjon finner du her: http://www.ntnu.no/kt/studier/prosjektoppgaver Hos Marin byggteknikk gjelder prinsippet: ’Først til mølla for først male’ Velkommen når som helst til å diskutere prosjekt / masteroppgave med oss. Avtal møte via E-post med oppført kontaktperson. Litt om Marin byggteknikk finner du her: http://www.ntnu.no/documents/10380/43037932-3645-4586-a1c7-e181fbd8e7b8 Selv om oppgavetekstene stort sett er på engelsk så er det mulig å skrive besvarelser på norsk (i samråd med veileder). Sist oppdatert: 10. April 2013

http://www.ntnu.no/bat/studier/oppgaver

http://www.ntnu.no/kt/studier/prosjektoppgaver

http://www.ntnu.no/documents/10380/43037932-3645-4586-a1c7-e181fbd8e7b8

http://www.ntnu.no/documents/10380/43037932-3645-4586-a1c7-e181fbd8e7b8



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9. Marin Byggteknikk /Marine Civil Engineering

9.1 Port and Coastal

9.1.1. Evaluation of port terminal equipment

Topic: Evaluation of different terminal equipment in smaller container

terminals in terms of cost-effective container handling.

In Norway and in countries with smaller ports that have container volume less

than about 150,000 TEU, mainly use RS (Reach Stacker) as handling

equipment. This has been a cost effective solution and with limited investment

in equipment and great flexibility. However this occupy large areas and when

there is scarcity of land, the question is what is the container volume to achieve

a cost-effective management by using a more space efficient container handling

equipment. Today more automated container handling equipment are

developed such as the Rubber Tyre Gantry (RTG)) and the Rail-mounted

gantry (RMG)) that allows the container volume to bring such equipment in

use to be lowered.

It is therefore interesting in a project to compare, for example, RS with RTG

cranes in a small terminal to find out what are the advantages, disadvantages,

savings, etc. Today, there are limited empirical data collected and to be

together just the kind of operations. The project may well continue in a

master's thesis in which a detailed computational model for optimization of

smaller terminals will be developed.

Prerequisites: TBA4292 TBA4145 Port and Coastal Facilities

Task type: Literature survey and numerical simulations

Number of students: 1

Cooperation partner: Borg Port, Fredrikstad, Norway; Port Director Tore

Lundestad

Contact person at NTNU: Øivind A. Arntsen, [email protected]

Possibility for summerjob in Borg Port , Fredrikstad.

9.1.1 Kaikonstruksjon oppbygget i stål

Norskspråklig kandidat er ønsket.

Kaikonstruksjoner ivaretar grensesnittet mellom skip og land og ligger i kystsonen. Dette er et av de

hardest miljøbelastede stedene hvor konstruksjoner bygges med påfølgende skader og redusert levetid.

Tradisjonelt bygges kaikonstruksjoner i betong og materialutvikling med forståelse av

nedbrytningsmekanismer har i de senere årene forbedret seg kraftig med påfølgende øket levetid og

forbedret konstruksjonskvalitet.

Byggekostnader har også øket kraftig i de senere årene og i den forbindelse er det naturlig å undersøke

mulighet for bruk av alternative byggematerialer som stål og trevirke. En kombinasjon av trevirke og

limtre benyttes i dag til bygging av mindre kaikonstruksjoner og strandpromenader.

Kreosotimpregnering klasse marin viser seg å motstå pelemark og gi trevirket god beskyttelse, samt

sikre konstruksjonens levetid. Trevirke som materiale er godt egnet til bygging av lettere

kaikonstruksjoner for passasjertrafikk med mindre båter men begrensning i styrke reduserer

muligheten for bruk i industrikaier og kaier hvor større skip anløper. Stål derimot er et materiale som

kan være godt egnet for tyngre kaikonstruksjoner så fremt at bestandighet håndteres på en riktig måte

og at materialforbruk optimaliseres. I dag benyttes stål til kystnære konstruksjonsdeler, men ikke til

komplette kaikonstruksjoner.

mailto:[email protected]



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Prosjektoppgaven består i å designe en mindre kaikonstruksjon bygget i stål etter gjeldende regelverk i

Norge. Konstruksjonen designes med basis i Norsk Standard NS-EN 1990 til NS-EN1999 og det tas

utgangspunkt i forskjellige prosjekterte levetider. Forskjellige byggemetoder som stedlig montering og

modulbygging vurderes. Avvik i byggeperioden spesielt med posisjonering av peler er vanlig ved

kaibygging og håndtering av avvik opp mot 0,50m i horisontal peleplassering inngår i oppgaven.

Stabilitet av kaikonstruksjonen med opptak av støtlaster fra skipsanløp og fortøyningslaster fra skipet

inngår i prosjektoppgaven. Det skal utføres en global stabilitetsanalyse av hele konstruksjonen hvor

horisontale laster følges helt inn i fundamenter.

Økonomi og byggetid er sentrale deler av oppgaven. Realistiske fremdriftsplaner med for de

forskjellige byggekonseptene skal leveres som en del av rapporten. Videre skal økonomien i

prosjektets undersøkes, både byggekostnader og levetidskostnader inkludert riving etter endt levetid.

Prosjektkostnader angis i nåverdiberegninger med basis i gjennomsnittlige renter og prisstigning de

seneste 5år gitt av SSB.

Korrosjonshastigheter i Eurocode og NA (NS-EN1993-5:2007+NA:2010) angir store forskjeller i

korrosjonshastigheter. Oppgaven skal også inneholde en sammenligning av levetidsforskjell og

prosjektkostnader for begge korrosjonshastighetene.

Arbeidet er en videreføring av en prosjektoppgave høsten 2012.

Aktuelle problemstillinger for en ny oppgave kan være.:

1. Konstruere et dekke som kan bære trafikklasten

Det lages ikke store nok rister per i dag hos de leverandørene som ble sjekket. Det er derfor behov for

å beregne og konstruere et dekke som er passende til dette formålet.

2. Design av knutepunkter

Bæresystemet må settes sammen på en funksjonsmessig bra måte. Det er et helt

symmetrisk bæresystem, derfor er det ikke nødvendig å designe alle knutepunktene for

seg selv, men enkelte utvalgte avhengig av lastkombinasjonene.

3. Festeanordning for fendere

Hvordan man skal feste fenderene til kaifronten er en utfordring det må sees på, også i

sammenheng med at man vurderer fendere som passer kaien godt.

4. Kaiens skjørt

Da dette er en stålkai må skjørtet konstrueres på en måte som ikke er gjort før, da vi ikke

kan støpe ned et skjørt i betong. Her vil det være mulig å være kreativ og prøve seg frem

med litt forskjellige løsninger.

Antall studenter: 1

Samarbeidspartner: Borg Havn, Fredrikstad, Norway; Port Director Tore Lundestad

Kontakt person ved NTNU: Øivind A. Arntsen, [email protected]

Veilder: Svein Ove Nyvoll, Nyvoll Concult. http://www.nyvcon.com/nor/about/

Mulighet for sommerjobb i Borg havn, Fredrikstad.

9.1.3. Intentionally blank


http://www.nyvcon.com/nor/about/



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9.1.4 Estimating the effect of kelp (Laminaria hyperbiorea) on the wave conditions at the

harbours Kvalsvik and Kvamme during the storm “Dagmar”, Christmas 2011.

The Norwegian Directorate of Fisheries held a seminar at the island of Runde on 16 and 17 May 2012

where different aspects on the harvesting of kelp, Laminaria hyperborea, were discussed. The

participants of the seminar were government managers, researchers, representatives of a kelp

harvesting company and local managers and land owners. Alf Tørum presented “The wave damping

effect of kelp – does the harvesting of kelp give reduced wave damping?. The answer is “Yes”.

During the discussions it was specially mentioned that the breakwater in Kvalsvika on Nærlandsøya

and at the mall boat harbor at Kvamme, Kvamsøya, Figure 1, were damaged during the storm

“Dagmar” during Christmas of 2011.

There were some interest to investigate what the wave heights at these breakwater were during

“Dagmar” and to which extent harvesting of kelp may have caused larger waves than without

harvesting.

The kelp harvesting company FMC Biopolymer expressed willingness to give information on their

harvesting of kelp outside the mentioned harbors prior to “Dagmar”. The Norwegian Coastal

Administration will give information on the breakwater at Kvalsvik and the damages during and repair

work after “Dagmar”. A visit to this breakwater is envisaged. The Norwegian meteorological Institute

will give hindcast data on the wave conditions during “Dagmar” at specific points in deep water

outside the area of interest..

During the project work the student shall familiarize himself with kelp , Laminaria hyperborea, how

much is normally harvested in a kelp field and the wav e damping effect of kelp.

During the Master thesis the student shall calculate by the use of a computer program how the wave

heights and direction will change toward the mentioned harbors if there had been no kelp. The

influence of kelp on the wave heights shall thereafter be estimated. Finally the observed damage

effects on the breakwaters should be compared with the estimated damage from the wave height

calculations.

Type: Numerical modelling using commercial software

Prerequisites: TBA4265 Marine Physical Environment ,

Contact person at the department: Øivind A. Arntsen, [email protected]

Supervisors: Raed Lubbad , Øivind A. Arntsen, Alf Tørum




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Figure 1. Extract from the sea map.

Kvamme small

boat harbour

Kvalsvik

harbour

Runde



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9.1.5 Determination of wave slamming forces from measured data

Experiments have been conducted in the Large Wave Flume at the ForschungsZentrum Küste

(Hannover, Germany). During these experiments a truss structure has been exposed to forces from

breaking waves, and the response has been measured. Such truss structures could be used as support

structures for offshore wind turbines in shallow waters, and it is important to understand the loads

properly, in order to design an efficient structure.

The goal of this project is to find the forces acting on the structure from the responses. This is not

trivial, since the slamming forces are of very short duration, but still show a

characteristic time history. Here the exact form of this force time-history is

of interest. In order to obtain it, in this project the Duhamel integral

approach will be used, and the force (input) will be numerically optimized,

such that the response (output) is as close as possible to the measured

response.

Alternatively, the frequency-response-function approach or modal methods

can be used. The measurements include hammer pluck tests at different

locations, and excitation from regular non-breaking waves, which can be

used for these analyses.

This project will enable the students to gain experience in state-of-the-art

analysis of structural response measurements in offshore engineering.

The project work is assumed to be continued in a thesis, in which

the force reconstruction method will be further improved.

Prerequisites: Basic knowledge of structural analysis,

Wave forces

Task type: Literature study, Data analysis

Number of students: 1-3

Contact person at NTNU: Øivind Arntsen,

[email protected]

Co-advisor: Alf Tørum, [email protected];





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9.1.6 Composite breakwater

A composite breakwater may be an attractive breakwater concept for deep water, say 30 – 50 m.

Figure 1. The caisson may be a plain front wall or may have a circular form, as indicated in Figure 1.

The circular form may be an advantageous form because the wave pressures and internal pressures are

taken by axial forces. Wave heights in the range Hs = 6 – 11 m and peak periods in he range Tp = 14 –

17 s should be considered.

Figure 1. Conceptual sketch of a composite caisson breakwater.

Annette Jahr (2010), Tørum et al. (2011), carried out a study of the wave forces on a composite

breakwater using only regular waves.

Research:

During the project work the student shall familiarize him/herself with the problem area and with

previous investigations, including some calculations to be decided later. During the master thesis

work in the spring semester 2013 the student shall carry out experiments to investigate further the

wave forces from irregular waves on the circular caissons. For comparison the student shall also carry

out tests on a plain wall caisson. Although the study is general the following prototype conditions

should be kept in mind:

Water levels: ± 0; Sea bottom at: – 55 m; Caisson crest height: + 12.5 m; Caisson bottom: - 25 m

Two rows of circular cylinders, each with a diameter D = 20 m, filled with stone/gravel/sand. Concrete

wall thickness 50 cm. Core material: 0 – 1000 kg; Wave heights: Ultimate limit state (ULS): Hs = 8.4

m, Tp = 15.8 s ; Load combinations: 1.0G+1.3E (G = dead weight load, E = environmental loads);

Accident limit state (ALS): Hs = 10.4 m, Tp = 17.3 s; Load combinations: 1.0G+1.0E.

References:

Jahr, A. (2010): Composite breakwater with circular caissons. MSc thesis, NTNU, June 2010.

Tørum, A., Jahr, A. and Arntsen, Ø. (2011): Wave forces on a composite breakwater with circular

cylinder caissons. Sent for possible publication.

Task type: Literature survey, calculation and laboratory experiments

Prerequisites: TBA4265 Marine Physical Environment, TBA4145 Port and Coastal facilities or

similar.


Contact person: Alf Tørum, [email protected] / Øivind A. Arntsen [email protected]

30 – 50 m 20 – 30 m

Plan view





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9.1.7 Floating breakwaters

Floating breakwaters has an advantage over fixed wave absorbers in areas with great depth and limited

wave exposure. The cost of building a conventional breakwater increases significantly with water

depth and for a number of marinas along the Norwegian coast, these solutions can be completely

obsolete. The purpose of a wave absorber is to reduce the wave height on the leeward side relative to

the incoming waves. Reduction in wave height inside the breakwater occurs either because the wave

loose energy by breaking and the energy passes into turbulence or by that the breakwater reflects the

wave.

The project work fall 2013 the candidate shall perform a literature survey and provide data on how a

caisson type submerged breakwater behaves and calculate reflection and transmission coefficients, and

suggest possible modifications that can lead to improved wave protection. Anchoring systems,

mooring forces, links and fender systems between elements may also be considered. Use of REEF3D

for CFD and/or WAMIT for potential flow approach.

In the master thesis work, there could be several ideas to follow, depending on the results of the

project and the interest of the master student. Here we suggest the following: The combination of a set

of submerged breakwaters and a floating breakwater shall be tested in the laboratory. Floating

breakwaters become inefficient when the breakwater width is less than half the wavelength. This

means that if the incoming wave has a wavelength of 20 m the breakwater has to be 10 meters wide to

be most effective. When waves pass over submerged breakwaters a nonlinear process very often

transforms the waves by making the wavelength shorter (approx by a factor 0.5) , but not necessarily

reduce the wave height enough. Since the wave length is reduced the 10 m wide floating breakwater

may no be efficient up to 40 m long incoming waves. So far these are speculations. Therefore we will

set up a test facility in a wave flume to investigate this. And also see if the data fits results of the

numerical models.

Preliminary experiments (S. Yu. Kuznetsov, 2012)

Physical mechanisms of secondary waves formation in coastal zone and possibility of its application to

coastal protection, Copedec 2012, 20-24 Feb 2012, Chennai, India.

Task type: Literature survey, numerical modelling, calculation and laboratory experiments.

Prerequisites: TBA4265 Marine Physical Environment, TBA4145 Port and Coastal facilities or similar.


Contact person: Øivind A. Arntsen [email protected]




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9.1.8 CFD modeling of OWC wave energy converters

An OWC (Oscillating Water Column) device consists of an air filled chamber, which is partially

submerged in the ocean. Due to the wave motion of the sea, the water column inside the chamber

moves up and down, initiating oscillatory airflow in the upper part of the chamber. The air exits and

enters the chamber through a Wells turbine, which is optimized for low-pressure air flow and always

rotates in the same direction.

The hydrodynamics and wave kinematics around and inside the OWC device heavily influence its

performance. In this project, a simplified 2D setup will be used for numerical investigations of the

OWC device. The numerical wave tank REEF3D (www.reef3d.com) will be used for this task. The

level set method is employed for the calculation of the complex free surface. The flow problem is

solved as a two-phase flow of water and air, with the free surface represented by the interface between

the two phases. With this method, it is possible to calculate the motion of the free water surface and

the air flow inside the OWC chamber in great detail.

During the project the 2D model will be implemented and first simulations will be performed.

The project work is assumed to be continued in a thesis, during which parameters of the design will be

varied, and the power production of the turbine will be studied in more detail.

Prerequisites: TBA4265 Marine Physical Environment, CFD

Task type: Literature study, CFD Modeling


Contact person at NTNU: Øivind A. Arntsen, [email protected]

Hans Bihs, [email protected]

http://www.reef3d.com/




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9.1.9 Wave propagation over rough topography

Numerical wave transformation models (e.g. Spectral and

Boussinesq models) are implemented in software packages such

as MIKE21, Delft3D/SWAN, etc. These software packages are

developed mainly for gentle variable bottom topography. The

question becomes how well they can predict wave

transformation on a rugged coast like the Norwegian coast.

In the project work the student shall familiarize himself/herself

with the use of MIKE21. In addition, the student shall develop

routines to analyse wind and wave data provided by the

Norwegian meteorological institute in order to establish the deep

water sea state.

The project work is assumed to be continued in a thesis where the task is to use MIKE21 to transfer

the deep water waves to a specific location on the Norwegian coast. The student will compare the

results from the spectral wave models with those from the Boussinesq models and if possible with

field data.



Contact person at the department: Raed Lubbad, [email protected]

Supervisor: Raed Lubbad , , Øivind A. Arntsen




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9.1.10 Numerical modelling of sediment transport and coastline evolution

The coastal zone is an extensively used area for many activities and industries. Around half of the

world’s population live or work within one or two hundred kilometres of the coastline. Because of the

high population density and the extensive development in these areas, it is very important to know the

dynamics of the forcing and response of the coastal system involved and how to model them for an

appropriate choice and design of measures.

There is a number of numerical models present that are available for predicting coastline evolution

using different formulations. Some software packages such as Delft3D, TELEMAC etc. are available

through open source whereas some packages such as MIKE21 are available commercially. The

available models are also classified based on their temporal and spatial scale of application. Delft3D

and MIKE21are applicable over a period of months to decades and can be applied to coastlines of

kilometres whereas models such as XBeach are applied over a period of days to months and a cross a

distance of several hundred meters only.

In the project work the student shall familiarize himself/herself with the use of MIKE21 or Delft3D.

In addition, the student shall develop routines to analyse wind and wave data provided by the

Norwegian meteorological institute in order to establish the deep water sea state

The project work is assumed to be continued in a thesis where the task is to use MIKE21or Delft3D to

study the sediment transport and the coastline evolution at a specific location on the Norwegian coast.

If possible, the student will compare the simulation results with field data.



Contact person at the department: Raed Lubbad , [email protected]

Supervisor: Raed Lubbad, Øivind A. Arntsen.




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9.1.11 Study of Wave-Current-Structure Interaction using Computational Fluid

Dynamics

A good description of the incoming wave field is important for a safe and economic design of

offshore structures. The wave-structure interaction causes changes in the wave properties. Wave

runup on a structure is one such phenomenon of interest. Wave runup involves an amplification of

the wave amplitude in the proximity of the structure. This has consequences on the safety and

strength of the structure due to wave overtopping and wave slamming effects that can occur. The

presence of a current in addition to the wave field makes the problem more complex with an

additional force component playing a role. The study of wave runup on offshore structures is thus an

important aspect of offshore design. Application of Computational Fluid Dynamics (CFD) to such a

scenario is an interesting approach as it provides a detailed description of the fluid flow around the

structure. This provides good insight into the wave-current-structure interaction and helps in better

understanding the hydrodynamics involved in the process.

The objective of this project work is to use a CFD code being developed at the Department of Civil

and Transport Engineering to evaluate the wave runup on a cylinder in a numerical wave tank. The

wave runup in presence of only waves and combination of waves and current is to be studied. The

change in runup with change in wave properties and cylinder size is also to be explored. The results

obtained from the CFD code are to be compared to the experimental results.


Task type: Numerical analysis

Contact Persons: Hans Bihs ([email protected]) , Øivind A. Arntsen ( [email protected]) ,

Arun Kamath ([email protected]),






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9.1.12 CFD simulations to analyse wave impact and uplift forces on a

horizontal platform

The phenomenon of wave impact on structures is important from the point of view of design,

stability and safety of a marine structure. Understanding the action of extreme waves under a

horizontal structure located close the free surface can help in better design for these conditions.

Decks of coastal and marine structures are built of many independent units placed together. The

failure of these decks could be either due to the global failure of the whole platform or due to the

local failures of the individual members. Wave impact can cause high local forces, which can cause

failure of the individual members. Wave slamming involves a rapidly varying peak uplift pressure and

a slowly varying uplift pressure. The forces resulting from the rapidly varying peak pressure have can

cause local failure of the members of a platform.

This project aims at simulating wave-structure interaction with a focus on uplift forces on a thin

plate under the action of a solitary wave. The study will be carried out using a CFD model adapted to

be a numerical wave tank, developed at the Department of Civil and Transport Engineering. The

relation between the freeboard and the maximum uplift force is to be explored. The results obtained

from the numerical simulations are to be compared with the experimental data.


Task type: Numerical analysis

Contact Persons: Contact Persons: Hans Bihs ([email protected]) , Øivind A. Arntsen (

[email protected]) , Arun Kamath ([email protected]),






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9.2 Offshore Marine Civil Engineering

9.2.1 Free spanning pipelines

Pipelines on uneven seafloor will exhibit free spans in

case they cannot follow the geometry of the sea bottom.

In this project the student shall investigate the conditions

for and behaviour of free spans and investigate solutions

to limit the free spans. Of particular concern is the analysis of pipelines under free spanning

conditions. The project work might be continued in a master thesis project.

Prerequisites: TKT4201 Structural dynamics or TBA4275 Dynamic response or similar

Recommended supplementary course: TBA4116 GEOTECH ENG AC, TKT4108 DYNAMICS AC

Task type: Calculation task, numerical modelling, literature survey


Cooperation with: University of Stavanger

Contact person: Ove T Gudmestad, [email protected]

Contact person at NTNU: Knut V. Høyland, [email protected]

9.2.2 Marine Operations in Cold Climate

Marine operations taking place in cold climate regions have to take into

consideration the specifics of the climatic conditions:

During installation the work season may be limited due to ice and

drifting ice. During the fall season polar low appears and

unpredictable weather makes planning for installation difficult.

Icing might occur relatively early during the fall.

During operations of the production from an offshore oil and gas

field, the weather conditions might pose severe limitations to

operations as icing and ice conditions may pose specific

requirements.

The student shall assess the challenges and limitations of carrying marine

operations in cold climate. The installation and operation phases shall be

assessed and the ice free as well as the ice covered seas shall be discussed.

The project work may be continued in a master thesis project.

Prerequisities: AT 327 Arctic Offshore Engineering,

Recommended supplementary course:, TKT4108 DYNAMICS AC , TMR4130 RISK SAFETY MAR

TRAN

Task type: Calculation task, Literature survey

Number of students: 1,




9.2.3 Field development in cold climate

Sub Title: Aspects that influence on offshore hydrocarbon field development scenarios in cold climate

regions with emphasis on the Barents Sea







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Oil and gas development in cold climate areas represent challenges additional to those experienced

further south. The project will emphasis on aspects related to the physical environment, on flow in

pipelines and on technology for field development. Risk analysis and selection of safety level shall be

important part of the discussions. Economical assessments shall be conducted to understand the

sensitivity to different development schemes

Prerequisities: TBA4265 Marine Physical Environment

Key words: Barents Sea

Type of project: Literature + analytical assessment of hydrocarbon development schemes

Number of students: 1 to 2




Continuation of project: Can be extended into Master Thesis.

9.2.5. Installation of offshore wind turbines

Sub Title: Methods for efficient installation of wind turbines in harsh offshore climate

Installation of offshore wind turbines represents a very costly element. In open seas waiting on

weather can increase the costs substantially and cause wind farms to become non-economical

It is therefore necessary to compare different methods for installation and investigate new methods

It should be noted that new methods that can reduce waiting on weather could make a substantial

contribution to the economic feasibility of offshore wind farms.

Prerequisities:: TBA4265 Marine Physical Environment

Key words: Offshore wind turbines, marine operations, lifting

Type of project: Literature + analytical assessment of installation methods for offshore wind turbines

Number of students: 1to 2


Contact person: Ove T Gudmestad,, [email protected]


Continuation of project: Can be extended into Master Thesis







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9.3 Arctic Technology (ice mechanics and ice actions on marine structures/vessels)

When designing coastal and marine structures (including vessels) the actions from floating ice covers

often gives the most important environmental actions. There are mostly three scenarios that can be

critical: icebergs, ice ridges and level ice. The suggestions below are offered within the SAMCoT

project (http://www.ntnu.edu/samcot ).

9.3.1 Level ice action, ice-induced vibrations and uncertainties.

It is possible to choose a topic with joint supervision from Veritas (DNV) or Reinertsen. Contact

person at NTNU: Knut V. Høyland, [email protected] or Sveinung Løset,

[email protected] .

Ice induced vibrations – a tool for prediction of cyclic loading due to ice crushing (with

Morten Bjerkås from Reinertsen)

Variability and uncertainty related to measured ice properties (DNV/ NTNU)

Analyse data about dynamic ice –structure interaction from laboratory tests (DNV/NTNU)

Numerical model for ice-induced vibrations (DNV/NTNU)

Velocity effects of high pressure zones in ice-structure interaction. (with Ole Øiseth K-Tek)

Ice induced vibrations of offshore structures (with Ole Øiseth K-Tek)

Ice mechanical experiments in NTNU ice-lab, e.g. cyclic testing.

9.3.2 Ice ridges and ice ridge actions

It is possible to choose a topic with joint supervision from Veritas (DNV). Contact person at NTNU:

Knut V. Høyland, [email protected].

Ice ridge action on offshore structures - ice ridges as extreme ice features

Ice ridge action on offshore structures – material modeling FEM (SAMCoT)

Ice ridge action on offshore structures – experiments in NTNU ice-lab (SAMCoT)

Ice ridge action on offshore structures – analysis of ice ridge geometry (how deep and how

wide is the consolidated layer)

Ice ridge action on offshore structures - How to produce sale-model ice ridges

Ice ridge action on offshore structures - Ice rubble formation on sloping structures

9.3.3 Icebergs


Sveinung Løset, [email protected] .

Drift of icebergs in the Barents Sea

http://www.ntnu.edu/samcot







17

9.3.4 Icing


Sveinung Løset, [email protected].

Marine icing

9.3.5 Development of laboratory or full-scale procedures and instrumentation.

Contact person at NTNU: Knut V. Høyland, [email protected] or Sveinung Løset,

[email protected].

Full-scale ice forces from MRU, compare full-scale and model scale data (DNV/NTNU)

Instrumentation of ice growth tank and characterization of ice

Develop a practical and accurate method to determine the density of sea ice

Study the reliability and accuracy of ice pressure sensors (tactile pressure sensors)

9.3.5 Ice thickness and level ice properties Contact person at NTNU: Knut V. Høyland, [email protected]

Level ice thickness in the Van Mijen fjord in Svalbard, analysis of existing data and / or

perform new measurements on Svalbard / UNIS

Ice texture and the brine and gas volume in first-year sea ice – seasonal development,

measurements on Svalbard / UNIS

In most of these task it is possible to have a part-time stay at UNIS on Svalbard. Please get in

touch with Sveinung Løset / Knut V. Høyland if you are interested in this.

9.3.6 Ship-ice interaction: Analysis of full-scale data

A better understanding of the interaction processes between ship and ice allow us to improve our

models for ships operating in ice infested-waters, e.g. transporting, station keeping, performing ice

management, etc.

Full-scale data from several surveys with the

icebreaker KV-Svalbard will be available for this

study. In additions to the ship measurements

(movements, propulsion, etc.), video data from

several cameras mounted on the ship are

available. The video records capture the ice

conditions in front of the ship and also the

interaction processes between the incoming ice

and the ship bow.

The student should analyse the video data and try

to evaluate the icebreaking patterns, movement of

the ice floes interacting with the ship, correlation

between the ice conditions and ice resistance to

the ship motion, etc.

During this project the student will acquire






18

knowledge on the underlying processes of ship-ice interaction. The student shall familiarize

himelf/herself with data analysis techniques and especially the image analysis.

Recommended subject: TBA4265 Marine Physical Environment; AT327 Arctic Offshore Engineering

Key words: Arctic offshore

Type of project: Data analysis (Image analysis)


Cooperation with: SAMCoT

Contact person at NTNU: Raed Lubbad, [email protected]

Continuation of project: Can be extended into a Master Thesis

93.7 Transport of ice along a structure

Numerical simulations of a floater (ship or buoy) in ice involve modelling a wide range of physical

processes related to the dynamical coupled floater-ice-fluid interaction, such as impacts, friction,

buoyancy, hydrodynamics, fracture and fragmentation of ice. The task should focus on how fluid flow

models, e.g. FLUENT, can be used to model the transport of broken ice pieces along the hull of a

floater. The numerical results should be compared with model-ice test results from the Hamburg Ice

Basin, Germany. This gives the student an excellent opportunity to validate his simulations. The

student will be offered a summer job in 2012 to work on the data as well as a visit to the Hamburg Ice

Basin.



Type of project: Numerical calculations


Cooperation with: SAMCoT

Contact person: Sveinung Løset/Raed Lubbad


9.3.8 Analysis of Model Ice Basin Tests of a ship in broken ice

A number of laboratory tests are performed with two vessels in broken ice in the Hamburg Ice Basin,

Germany. The data from the tests will be made available for the student and he shall perform analysis

of how the ice concentration, drift speed and floe size affect the load on the vessel. As an option the

student may also study the effect of the characteristics (hull shape) of the two vessels on the loads. The

student will be offered a summer job in 2012 to work on the data as well as a visit to the Hamburg Ice

Basin.



Type of project: Numerical calculations


Cooperation with: Dynamic Positioning in Ice

Contact person: Sveinung Løset





19

9.4 Offshore Wind Turbines

9.4.1 Certification analysis of a full-height lattice tower support structure

The Norwegian Research Centre for Offshore Wind Technology

(NOWITECH) is developing a 10 MW bottom-fixed reference wind

turbine. Our group is responsible for the design of the support structure,

which will be a novel lattice tower (see image).

This lattice tower has been analysed with special wind turbine simulation

software in the time-domain (DNV Sesam, FEDEM Windpower, GL

Garrad Hassan Bladed) and our own tools for pre- and postprocessing

(MATLAB). We have optimized the weight of the structure while

respecting the design limits. Unfortunately, a 10 min loadcase simulation

takes around 1 hr of simulation time, so the tower has been designed by

considering only a few loadcases. This means that the fatigue damage is

only estimated roughly.

During this project the student shall run the full certification suite of

loadcases from the IEC 61400-3 standard and check if the structure fulfills

the design limits (ULS and FLS), and by what margin.

This project will enable the students to gain experience in state-of-the-art

engineering practice for offshore wind turbine projects.

The project work is assumed to be continued in a thesis, in which

simplified methods for fatigue analysis of offshore wind turbines shall be

developed and tested.

Prerequisites: Basic knowledge of structural analysis

Task type: Literature study, Simulation, Postprocessing


Contact person at NTNU: Michael Muskulus, [email protected]




20

9.4.2 Component design for a future 10 MW offshore wind turbine

NOWITECH is designing a 10 MW wind turbine for

use in both local and international research projects on

large offshore wind turbines. The existing design

includes a 141 m diameter rotor, the nacelle frame, and

a 160 m high lattice tower (jacket). However, key parts

of the load path between the rotor and seabed have not

yet been designed; specifically, the rotor hub, the main

shaft, the transition piece between the nacelle frame and

tower legs, and the pile sleeves at the base of the tower.

The task is to design and analyze one or more of these

components.

The methods used for the dynamic analysis of wind

turbine structures are similar to those used in the

dynamics of bridges, offshore structures, or buildings –

though on wind turbines, the large, spinning rotor makes

the dynamic loads of even greater importance.

Students with a background or interest in these fields will

find the present project to be a natural fit. This is also an

opportunity to gain exposure within the research

community at NTNU, and the industry partners of

NOWITECH.

NOWITECH is a research centre for offshore wind technology. It is based in Trondheim, and includes

NTNU, Sintef, IFE, and industry partners (see http://www.sintef.no/projectweb/nowitech/).

Prerequisites: Knowledge of structural analysis and structural design

Task type: Literature study, Modeling with wind turbine analysis software,

Simulations


Contact person at NTNU: Karl Merz, [email protected]

Michael Muskulus, [email protected]

http://www.sintef.no/projectweb/nowitech/





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9.4.3 Sensitivity analysis of offshore structures

Offshore structures contain many members and there

are a lot of parameters that can be changed. In order to

have an economic design, the structures should ideally

be designed for each different site individually.

However, this is time-consuming and expensive, and

designers would very much prefer if they could use a

good design for a lot of different site conditions (e.g.,

different water depths and wave climates) with only

small changes. For example, for a typical jacket for an

offshore wind turbine, one possibility is to increase

the length of the piles at the bottom (stick-up).

It is important for designers of such structures to know

how much the performance (e.g., load distributions or

fatigue lifetime of joints) changes when changing the

design. Sensitivity analysis is a collection of methods

and tools for obtaining such information, and is

widely used in engineering practice.

In this project the student shall analyze the dynamics

of an offshore wind turbine support structure using

computer simulations.

A few parameters of the design (e.g., pile stick-up length, bottom leg distance) shall be varied, and

both local and global sensitivity analysis shall be performed. Local sensitivity analysis is based on

calculating gradients, i.e., assuming a linear relationship between parameter changes and performance

changes. The goal is to assess how accurate this method is. Global sensitivity analysis will be

performed by fitting a simple nonlinear (e.g., quadratic) curve to the simulation results.

The project work is assumed to be continued in a thesis.

Prerequisites: Basic knowledge of structural analysis and structural design

Task type: Literature study, Simulations, Statistical analysis






22

9.4.4 Mooring systems for floating wind turbines

Floating wind turbines are an interesting option for

deep waters (> 60m). Being floating structures, these

need a stationkeeping system. The most common

option is a catenary mooring system, in which a chain

provides a restoring force through its self-mass. If the

floater moves, more chain is lifted up from the ground,

increasing the restoring force, i.e., the mooring system

has a nonlinear stiffness characteristic. Especially for

water depths <100 m this nonlinearity can be quite

strong and the question is how a good mooring system

has to be designed under these conditions.

In this project the student shall implement a simulation

model in offshore analysis software (DNV Sesam) and

perform time-domain simulations and a parametric

study.

The wind turbine will be modelled as a rigid body with

six degrees of freedom. Changing the parameters of the

mooring system, the goal is to minimize the movements

of the structure, while keeping the mooring line

tensions well below the breaking strength.

This project will provide the student with state-of-the-

art experience in the design of offshore structures and

the use of DNV software.


Prerequisites: Basic knowledge of wave forces and hydrodynamics

Task type: Literature study, Simulations






23

9.4.5 Second-order wave forces on floating wind turbines

Linear wave theory is characterized by closed orbits, and a

floating structure will experience a zero mean force. However,

real waves are nonlinear, and second-order nonlinear waves

introduce both a mean drift force and an additional low-

frequency excitation. Because there is typically little damping in

the system, this can result in relatively large motions of the

structure.

In this project these effects and their importance shall be studied

for a typical floating wind turbine. The turbine will be

implemented in DNV Sesam software as a simple rigid-body

with six degrees of freedom. The software calculates the second-

order wave forces in time-domain simulations.

The student shall implement a numerical model, study a number of different loadcases and analyze the

importance of second-order wave forces for floating wind turbines.


Prerequisites: Basic knowledge of wave forces and hydrodynamics

Task type: Literature study, Simulations






24

9.4.6 Simplified dynamics of offshore structures

Offshore wind turbines consist of two major parts:

the wind turbine itself, and a support structure. The

dynamics of the wind turbine is quite complex,

being governed by nonlinear, time-dependent

aeroelastic effects, rotational machinery, and a

control system. The dynamics of the support

structure, however, is relatively simple. In fact, in

the oil & gas industry support structures are

typically designed with simplified methods (e.g., in

the frequency domain), at least for basic design

purposes.

In this project the student shall investigate simplified approaches for characterizing the dynamics of

support structures for offshore wind turbines (e.g., jacket structures). These can be transfer functions,

frequency-domain methods, or black-box statistical approaches. These methods shall be implemented

(e.g., using MATLAB) and their predictions shall be compared with time-domain simulations in finite

element software.


Prerequisites: Structural dynamics

Task type: Literature study, Simulations, Statistical analysis






25

9.4.7 Topology-based optimization of an offshore jacket for a wind turbine

Offshore wind turbines for medium water depths (30-60m) are typically designed with jacket-type

support structures. These jackets consist of welded tubular steel members in four legs and a number of

X-braces, and are relatively complex structures. Each member is characterized by its diameter and

thickness. The main design driver is fatigue, both from wave loading and from vibrations due to the

rotating turbine on top. Because there are so many parameters with these structures, current designs

use a lot of steel and are relatively expensive. It is one of the key challenges for offshore wind to

reduce the weight of these support structures.

Our group has worked on optimization of support structures for some time, and has developed models,

algorithms and pre- and postprocessing tools for this task. Up to now, however, the optimization has

only considered diameters and thicknesses, but the location of the nodes (defining the heights and

aspect ratios of the X-braces) has always been fixed.

During this project the student shall extend the existing optimization tools such that also the topology,

i.e., the locations of the nodes can be changed. The work will be done in cooperation with one of the

leading designers of offshore wind turbine jackets, OWEC Tower AS (Bergen). Students will gain

insight into actual structural design practice in the growing offshore wind industry.


Prerequisites: Structural analysis

Task type: Literature study, Programming (MATLAB), Simulation






26

9.4.8 Implementation of a flexible beam in the multi-body inertial formulation

Wind turbines are typically modeled with beam elements, and these are used both for the blades and

for the tower. The resulting structural model is used for design, optimization and certification of the

turbine. This is a standard FE problem, but since the blades are rotating, a multi-body formulation is

needed, and there do not exist many analysis codes with this capability and features for realistic wave

and wind loading. The existing codes are relatively simple and use the co-rotational formulation which

assumes small elastic deformations.

A more accurate approach is the inertial formulation, in particular the one developed by Park and

colleagues at NASA in the early 90s, where it was successfully used for the analysis of satellites and

space stations. This approach uses global inertial coordinates, implements the rotational constraints by

a penalty method, and uses a nonlinear strain formulation. It is well documented in a number of

articles and PhD theses, and lends itself excellently to a parallel implementation.

During this project the student shall implement the beam element developed by Park and colleagues,

either in MATLAB, Fortran or another common programming language, and validate it by simulating

a rotating beam that is spinning up.



Task type: Literature study, Programming (MATLAB or other language)






27

9.4.9 Alternative materials for offshore support structures

Offshore structures are normally constructed from ductile carbon steel.

However, different materials such as aluminium, concrete, or high-

strength steels could be an alternative. For wind turbine support

structures the use of such alternative materials has not been evaluated in

sufficient detail.

In this project, the student shall analyze a simple design for an offshore

wind turbine support structure using such alternative materials, and

compare it with a traditional design using steel, assessing performance

and costs.

The project will be performed in cooperation with relevant Norwegian

companies (e.g., Norsk Hydro or Dr. techn. Olav Olsen).



Task type: Literature study, Modeling and Analysis


Contact person at NTNU: Michael Muskulus,

[email protected]




28

9.4.10 Cost of offshore wind energy

When designing and optimizing a support structure for an offshore wind turbine, it is very important to

have a good estimate of the manufacturing, installation and maintenance costs of the structure.

Although quite a lot of data exists, a good cost model does not exist at the moment, and the structural

design is often only optimized by minimizing the weight of the structure.

In this project the student shall compile the known data and literature, and come up with a suggestion

for the typical costs of jacket type support structures for offshore wind turbines. Since such a model

will include some uncertainty in the parameters, an important goal is to identify which parameters are

of major relevance (cost drivers) and which are not.



Task type: Literature search and study, Statistical analysis


Contact person at NTNU: Michael Muskulus,

[email protected]




29

9.4.11 Improved O&M strategies for a large offshore wind park

Operation and maintenance (O&M) contributes a significant part (15 percent and more) to the total

cost of an offshore wind turbine. After failure of a subsystem, a maintenance crew needs to be

transported to the turbine, which is not always possible due to wave height limitations. Repairs need a

certain time and maximum wind speed, and possible weather windows can be rather short, such that

repairs need to be scheduled cleverly. Even then, unforeseen changes in weather conditions can make

it necessary to interrupt a repair or maintenance action and resume it at a later time.

A stochastic simulation has been implemented in MATLAB and allows to simulate the operating

phase of an offshore wind park. The aim of this project is to improve this tool. In particular, currently

the weather forecast is assumed to be 100 percent reliable for a certain numbers of hours, and

completely unreliable beyond that. Also the current scheduling strategy is relatively simple (see image

above). Failure rates are assumed to be constant during the whole lifetime of the wind park, which is

also unrealistic. One or more of these features shall be improved.

After improving the tool, the main goal is to analyze how much cost can be saved for better

maintenance strategies. This project will be done in close cooperation with SINTEF Energy.


Prerequisites: Basic knowledge of simulation and statistics

Task type: Literature study, Programming (MATLAB or other language), Simulation






30

9.4.12 A simulation model for marine growth

Marine growth is the common name for a

number of different organisms that grow on

offshore structures. The growth and its mass

can be significant and this changes the

dynamics of the structure – so that offshore

designs need to be checked against respecting

the design limits with marine growth included.

The relevant offshore standards prescribe a

certain constant thickness of marine growth

(e.g., 100 mm for the North Sea in the DNV

rules). However, a special feature of marine

growth is that it actually changes over time.

In this project the student shall implement a simple stochastic computer model (e.g., in MATLAB) for

the growth of marine growth on a submerged steel structure and compare it with existing data from

offshore wind and wave energy projects. The project will be done in close cooperation with the

Department of Biology (NTNU).

The project work is assumed to be continued in a thesis, in which the impact of the marine growth on

the dynamics of a wind turbine support structure shall be investigated.

Prerequisites: Basic knowledge of simulation and statistics

Task type: Literature study, Data Analysis,

Programming (MATLAB or other language)






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9.4.13 Influence of top weight on support structure cost for an offshore wind turbine

New superconducting generator technology makes it possible to reduce the weight of the rotor-nacelle-

assembly of an offshore wind turbine significantly. However, this comes with a price – and a higher

reduction in weight will increase the cost more. Since the weight of the generator can be reduced more

or less freely by this technology (up to a certain minimum weight), it is important to know how much

cost can be saved for the support structure, and where the optimum lies.

During this project, the student shall analyze by simulation how smaller top weight influences the

dynamics and the resulting fatigue damage of a typical offshore wind turbine.

The project will be done in cooperation with DTU Wind Energy, who is a world-expert on

superconducting technology for offshore wind turbines.



Task type: Literature study, Parameter study, Simulation




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