Design of Artificial Seaweeds for Assessment of Hydrodynamic Properties of Seaweed Farms

106 Pages·2017·23.55 MB·English

by  Carina Norvik

Design of Artificial Seaweeds for
Assessment of Hydrodynamic Properties
of Seaweed Farms
Carina Norvik
Marine Technology
Submission date: July 2017
Supervisor: Dag Myrhaug, IMT
Co-supervisor: Pierre-Yves Henry, IBM
Andreas Myskja Lien, SINTEF Ocean
Norwegian University of Science and Technology
Department of Marine Technology

i
Preface
Thefieldofthebiomechanicsandhydrodynamicsofmacroalgaefirstcametomyattentionin
thesummerof2016,whenIworkedforSINTEFOceanundertheMacroSeaproject.Iwastasked
with the design of artificial seaweeds for assessment of hydrodynamic properties of seaweed
farms. The seaweed in question was Laminaria saccharina, the sugar kelp. Having previously
studiedbiotechnology,ataskallowingmetoutilizebothmybackgroundswasveryrewarding.
During the summer I realized that there was a lack of knowledge regarding the hydrodynamic
propertiesofseaweeds,andinparticularlyforseaweedswithcomplexshapes. Withthelimited
timeavailable,itwasthereforenotpossibletomakesimplificationofthecomplexmorphology
ofL.saccharinaandstillbeconfidentthatitwouldreproducethehydrodynamicpropertiesof
therealseaweed. Thematerialpropertiesandgeometryoftheartificialseaweedweretherefore
made to be as similar to the real seaweed properties as possible. The complex shape of the
artificial seaweed meant that individual models had to be cast, which is very time consuming
andcostly.Itisthereforeofinteresttoreducethecomplexityofthemodels,andtoworktowards
nothavingtocastindividualplants,butratherbeabletomassproducethembye.g. stamping
outmodelsfrompremadesheetsorcuttingstrips.
Theobjectiveofthismasterthesiswastoaddknowledgeregardingthehydrodynamicofsea-
weedforfutureassessmentofhydrodynamicpropertiesofseaweedfarmsbycomparingmodels
withsimplifiedmorphologyofL.saccharina. Themostsimplifiedmodelisjustaflatbladewith
the same outline as the complex models found during the summer 2016. The other model in-
cludestheundulateshapeseeninL.saccharina.
Trondheim,July9,2017
CarinaNorvik
ii
Acknowledgment
SpecialthanksgotothestaffworkingatthelaboratoriesatTyholtandValgrinda;TorgeirWahl,
TrondInnset,OleErikVinje,GustavJacobsen,KristianAgustinJensenandMarcusAlmehagen.
Withouttheirhelpandguidance,thedragexperimentscouldnothavebeenperformed.Iwould
alsoliketothankmasterstudentsBenedicteEliseFløgum,MarieFløAarsnesandAurélienLiné
for helping me during the experiments and looking out for my safety. Additionally, I would
like thank Aurélien Liné again for helping me mitigate distortion of the underwater footage. I
would also like to thank head of the Marine Technology department Sverre Steen for making
timeinhisbusyscheduletomeetmeandanswermyquestionsregardingsimilaritytheoryand
scaling.AthanksalsogoesPhD-studentValentinBrunoChabaudfordiscussionregardingpost-
processingandfilteringofdisturbanceofdragforcedata. Thesupportgiventomebymyroom-
mateAbbaElizabethCoronhasbeenveryimportanttome,andshouldnotgounmentioned. I
mustalsothankmymother,JuneBråthen,asshehasalwaysbeenmysupporter.Finally,Iwould
liketothankmysupervisors, scientistatSINTEFOceanAndreasMyskjaLien, post-docPierre-
YvesHenryandprofessorDagMyrhaug,forgivingmeguidanceandhelpingmethroughoutthe
lastyear.
List of Symbols
δρ Ratioofplantdensityinfullandmodelscale
δυ Ratiooffluidkinematicviscosityinfullandmodelscale
(cid:178) Strain
λ Scaleparameter
µ Dynamicviscosity
ω Cross-sectionalarea
Π Dimensionlessratioi
i
ψ Vogelexponent
ψ ’Bending’-plantVogelexponent
b
ψ ’Tensile’-plantVogelexponent
t
ρ Fluiddensity
ρ Plantdensity
p
ρ Plantdensityinfullscale
pF
ρ Plantdensityinmodelscale
pM
σ Surfacetension
Θ Temperature
iii
iv
υ Kinematicviscosity
υ Kinematicviscosityinfullscale
F
υ Kinematicviscosityinmodelscale
M
A Characteristicarea
AR Aspectratio
b Breadth
C Arbitrarydimensionlessconstant
(cid:48)
C Arbitraryconstant
C Dragcoefficient
D
C Liftcoefficient
L
Ca Cauchynumber
E Elasticmodulus
E Bendingmodulus
b
E Elasticmodulusinfullscale
F
E Elasticmodulusinmodelscale
M
E Bendingmodulusinfullscale
bF
E Bendingmodulusinmodelscale
bM
F Force
F Buoyancyforce
B
F Bendingreactionforce
b
F Dragforce
D
v
F Gravityforce
G
F Liftforce
L
f Naturalfrequency
n
F Tensilereactionforce
T
Fr Froudenumber
G Modulusofelasticityinshear
g Gravitationalacceleration
g Gravitationalaccelerationinfullscale
F
g Gravitationalaccelerationinmodelscale
M
I Secondmomentofarea
I Secondmomentofareainfullscale
F
I Secondmomentofareainmodelscale
M
J Flexuralrigidity
J Flexuralrigidityinfullscale
F
J Flexuralrigidityinmodelscale
M
KC Keulegan-Carpenternumber
L Length
L Length1
1
L Length2
2
L Lengthinfullscale
F
L Lengthinmodelscale
M
vi
M Mass
M Massinfullscale
F
M Massinmodelscale
M
p Pressure
q Numericalvalueofquantityi
i
R Radiusofcurvature
r Radius
Re Reynoldsnumber
St Strouhalnumber
T Time
t Thickness
T Periodofoscillation
A
T Appliedtorque
a
T Timeinfullscale
F
T Timeinmodelscale
M
U Relativevelocity
U Amplitudeofflowvelocityoscillation
A
U Relativevelocityinfullscale
F
U Relativevelocityinmodelscale
M
V Volume
V Plantvolume
p