A CFD Model for Wave Transformations and Breaking in the Surf Zone

93 Pages·2012·2.32 MB·English

by  Sreenivasa C Chopakatla

ACFD MODEL FOR WAVE TRANSFORMATIONS AND BREAKING IN THE

SURF ZONE

AThesis
Presented in Partial Fulillment of the Requirements for
the Dagres Master of Science in the

Graces

School of The Ohio Siate University

By
Sreenlvase C Chopakatle, BTeck

The Ohlo State University
003

Master's Examination Commies:
Dr. Thomas Lippmann, Adviser Approved by
Dr, Diane Foster, Co-adviser

Dr, Keith Bedford

Auviser

CWvI Engineering Gradvate Program
ABSTRACT

‘The commercial CED inedal FLOW-SD* (tle Ssierce, 1ee., Santa Re, VIM) is

ued to simclms two-dineasioca’ wave wavaforncation und viavs brotking across 2

yes ual volaetioe ave cocepuced

‘ascurally tarred beach profs. Fine scale p
35.5 axinue petiod over « wu-dineasional Peach profile mssaued during tho 1990
puttin Gelé expctionest, The made. is iver hy cbserved wave sgecrma obteined iu 8 m7

svater depths, and results comparod with 2 cross shore emay of aresmure sensors and

unneut actors speming she wict; ofthe null z0ae and “he spatial dstihation of save

lucaking pottemsobtalaod Sonn ven dats, Wave uivsipatio: is detenrined by a coped

furby'z1ws closute schome tel enlves the iusoumee Kine

J every und the diasipatior.
rate comspor, equations wi che Recormilized Group (RNC) extewsion mode). Yn te
calculations, wave ‘oséing ig a nameal comiyuence of the Flic dyzemies and Aves not

formulations, or bering ait‘ Cloodeomparisrn hetween

rcqnite the use of empiri
modeled and obocrved weve “righ! uesforacation, ween croseabore Now, ond weve

Tweaking variability suggests Una the model oun be ased as a. mmerical ‘abecesry sn

ctudy the wave breaking and Wissipevion process ix deca and perhaps leaé te ypoved

parumeterizations for rore computaticnally ellielen: acunvieal mods
Dedicated tu my parents

Mr. Shanttar Rae Chopakatla

‘Mrs, Savitei Chapakatia
ACKNOWLEDGMENTS:

AL Lie eul of my praduato studics at che Ohio Suara University, ender spervisio:
of Dr, Fom Zippawun, I beve a Ssrer understanding of dhe Samikci verse "yune dove

‘Bhova” (awning teaches gnd). Th wes a gral ecg ex2e

cube worng wit3 D
Tipomura, “Thank you very auch bose”

Sincere Cini to my 00 supecviso: Dr. Diane Foster v

o eonaeen, suggestions

‘ind encourageatent helped mu i s Jocg wry in Tay texearch ane 2 oriting hig
1 sant » then cur industrial eoTlaboeatnr Dr. John Richatdscn fiom Alden Lab,
Tne, for teaching me FEOR:3D" at tor as support aad encouragement ttroyhowt che
course of this aeojee:, Thatles to Dr. Kaith Bedford 4 helying, me endenaunud re
smumezieal solction eriployed in FLOW-30",
‘Thasiss 10 Jewes Bretiour, David Soncem and Mike Bedadwoy ore Flos

Salama, Ine,

nig us in wring oar own code far botexdary concitions and éaea
extction moculon sich FLOW-SD" and for eleborating upon some theocetiow” aspects

but

sofware.
Gracias to Heather Smith fo: shoring ber ideas abu! FLOWSD®, wo my tab
antes Teaniste Shoce for belsirg wich FORTRAN, Mulab wal eurmaviesl mettods abd

David Wels’ for bs usaf tips om Mah,
“The Seu Geunt ‘Technolgy pragrum yenorauby Sunda this prajeut with «uppont

fom Dr. Vijay Patong aud

jeTRewter,

Special euke so my fully

subers and fivende fb: thei: support and

ecsouragenent,

Aut nybody Cruise who deserves mention!
VITA,

August 25, 1977 soar - Rariagatdun, Lode
2000. onc PTesl, Ciel Engineering,
Tnéian Tastnne of Toehnilgy, Powsl
‘Mamba, Ina
2000 Murch 2093 nndReseatch, Agsociate,

Byed Pole: Research Center,
‘be Obie Stute Universiy”

_-Reaeaich Associats
OSI Adan Lab, ne. Pry
‘The Obie Stee Univesity

iecemrine: 2002.

PNELDS OF STUDY

Major Fie: Civil Freineerng
YABLE OF CONTENTS

Abate.
Detication.
Atknowledgreaas
Vite

List of Figures.

Chapters
1. mtoduetiom,
2. Theory.
‘Governing Fasten
hail aching schecne
Nomecical Solution.

‘Bowndary Conciians,

4 Numerical Methods...
Dowain Setup,
Sink LEI sressseronnvseone
Initial and Bonndery Conditions
Field Meta,

Rests
arse! Simtations,
‘Medei-Field Data Comparizons
5. Disenssion,
suaing.

7 Conelusious.

Intl Expoticruts on a Linc Slope.

“et Plats,

Apperais B Alli We
JAST OF FIGUBES

Fiaxe

1 “The ‘ep patel shows tis enserble-averaged wave height tens tixmation
exeuleied fo. Lippmann, ee, 1998, with circles inicaring wave height
ati. abtxinedl Fo the 1990 Lo.‘ expetimcat et “1, 1950 et 10.00 ain
¢pcctan and Kita, 1995), The aie pane. shows Le percentage
Teasing (Oh) av imei of ernseshore distros, with the fil
dobscrvstions 23 cicles and the model data as 2olid line. Bathymeuy is shown
in Ue lower panel

Scgmatic of te down end gil ayout form ur penosned with FOI:
20*, Ths domain is 850 a in tks exose-shorsdioction and 12 ar vectcalhy wih
dull ates vel at 8.19 fiomlebatlew. Rardou waves are generate ut he
Jef hunt boundary im abserasion} an er ia sina deepest e-tixé
oft domain (how by dowcsrtc arov). The comoutational nek aslowt :
‘vit 1700 ell inthe ezss-shoes direction ané. 128 cells in the verea” ration

(Cote ts he mach eats show inthe Figure are 3erely for schomatie

PupoRes) 2

4 Gsid Iooatious odie tne seine of horiantal und verti veloc
retained fru bs A.OW-3D" movlelrns. Asters indicate locations of velocigy

senscrs ip tie Dent exse-iment (ela sboven in Figure 2). Sensors wee densely
[packeu eiase Sn he andar end i, sulle dps us Feiler ea ate velocty
hauges due to wave breaking
1

The top panel shows a skapchos of the aiadel ul imlanee (680 te Ceram,
sacar by IKE, Scale onthe rg’ indiootos FRE ineasity in we, Weve
ening iy detenained (eau Lie The top Men of te water
ohio, “he lower pac] shove instanr, shaded by dissipation rate,

Scale onthe sight indicates dissipation rate a ass *, on lel seal EE

‘Tae series of , w and w fiom spatial location s-250 m in the down, Thetis
no visible uend in any 07 the time sovies and the corstant variance over the
indicated» stcionsry mo ¢el ron. Tetil cab period repsesenrs “ima lag for wae
jstarbanes to rch, 250 m from faLiay buungary, Gradual sant ofthe time series

ren 6

elevation fir First $09)

‘Timestask ae sf
10.2 sacond intervals, Right-lond-side seale incicates se= surfuce elevation ia

at

son. al run samp

ateterselatve to eid] ar level. The effet of Ue linear demping Mer lent
‘of che re is clearly evidest. 0

Vimeslack a7 MS wove heights compute over 25 second Suteals forthe ectre
rie, Riphehan‘-side scale indiestes wave Ee‘ghts in meceis. G-ovpy madulat‘ons
fesident nthe deere perl othe Curaain are leatroyed by weave bresking,qver Tie
SADR, erates 38

‘Timentack oi’ meer, seu nunfce elavation anevpate over 25 second jtarvas for
tho carne model =m. Kipst-aandeside sone indicates eievatoa in cetecs selative
othe sl water level. Low Grequeny sscilasions are vide and -esul frm
rcupy modilatious i je and reflected ow ficqueacy oscillatous..39

Lropagation of wave

ress in spsco-tme is shown in thie flgne (fpr the post spite
‘off peiod, 200-500). Wave speads can be approximated fia Ore slupe of de
propagation profile, rearing waves deterred om & SER cbrosbaldl of 0.5
18867 ane mated by p's signs, Initial breakers are shoo by cross mas.

Taxemple of tie ethuds use determine wave atalisice, Tan pansl show
rests and ‘ronghs identified 2119529 5. Bxzaking cress auc shown by plus signs
sand uan-brea:ing oes hy src, Tnokyhw are iuivated with aserisks, Vibe

ores saowssemenponding manual cutie slo (9) berween crest ca
rtovgh. Bottom pauls shaw asim TRE {1 tercon ces and novgh

used ox enla Po emtify hreaking eres a