A TWO-LAYER NON-HYDROSTATIC MODEL FOR WAVE PROPAGATION AT INTERMEDIATE DEPTH AND SHALLOW TILL RUN-UP
Waterwavesthatpropagatefromoceantothecoastexperienceaprocesscalled shoaling,namelyanincreaseinwaveamplitude,aswellasadecreaseinpropa- gation speedandwavelength.Inaddition,thenonlineareffectbecomesimportant when theamplitude-to-depthratiobecomeslargeenough,suchaswhenthewave has reachedacoastalare...
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| Format: | Dissertations |
| Language: | Indonesia |
| Online Access: | https://digilib.itb.ac.id/gdl/view/70708 |
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| Institution: | Institut Teknologi Bandung |
| Language: | Indonesia |
| Summary: | Waterwavesthatpropagatefromoceantothecoastexperienceaprocesscalled
shoaling,namelyanincreaseinwaveamplitude,aswellasadecreaseinpropa-
gation speedandwavelength.Inaddition,thenonlineareffectbecomesimportant
when theamplitude-to-depthratiobecomeslargeenough,suchaswhenthewave
has reachedacoastalarea.Themainchallengeofamathematicalmodelof
water wavesisitsabilitytoaccuratelycalculatewavevelocity,bothatmedium
and shallowdepths,andtotakethenonlineareffectsintoaccount.Bothplayan
important roleinpredictingthewaverun-upheightwhenitarrivesatthebeach.
Accordingtotheshallowwaterequations(abbreviatedasSWE),thewavepropa-
gation velocity(phase)isthesameforeachwavenumber.Meanwhile,accordingto
Airy’stheory,thephasevelocityofawavediffersdependingonthewavenumber;
this isknownasthewavedispersioneffect.Thedifferenceinwavepropagation
speed isquitesignificantinmediumdepthanddeepwaterareas.Therefore,to
be abletosimulatewavespropagationfrommediumdepthareatoshallowarea,
a modelthatcountdispersioneffectsisneeded.Inthisstudy,weadoptedatwo-
layer non-hydrostaticmodel,abbreviatedasNH-2L.Thismodelisquiteefficient,
because theverticalintervalisonlydividedintotwoparts,andinherewewill
discuss theaccuracyofthismodelinsimulatingwavepropagation,aswellas
shorelinedynamics.Anotherchallengeinimplementingthedispersivemodelis
the mechanismofwavegeneration,especiallytherelativelyshortwaves.Insome
cases thatusetheNH-2Ldispersivemodel,wavegenerationisimplementedusing
the embeddedinfluxingmethod.Inaddition,wealsodiscusstheapplicationofthe
embedded influxingmethodtoimplementtransparentboundaryconditions.
Variousmodelvalidationswerecarriedoutincludingsimulationofstandingwaves,
propagationofharmonicwavesonaninclinedplaneandaboveabreakwater,
propagationandrun-upofsolitarywaves,aswellassimulationofwavefocusing.
Validationiscarriedoutonexperimentaldataandoranalyticalresults.The
validation resultsshowagoodfit,whichindicatestheaccuracyoftheNH-2Lmodel
that weused.Finally,non-hydrostaticmodelsfortwo-dimensionalproblemsare
discussed; The1-layermodelreviewedwassuccessfullyvalidatedbysimulating
two testcases,namelythesolitarywavepropagationontheconicalisland,andon
the slopingbay. |
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