Dl).IHOC Qu6c GIA TP. H6 CHI MINH TRU<JNGDl).IHOC KHOAHOC TV NmEN V() THANH TAN , " ? 'fINI-I TOAN DONG CI-IAY , ~ , , ~ VUNG UIEN VEN nO - NUDCNONG Chuyen nganh : H<liDLtdngHl)c Mii 86 : 1.07.07 TOM TAT LU~N AN TIEN si V~T LY TP. H6 ChiMinh -2004 Cong trinh hoan thanh t~i: Bc) m6n V~t Ly MOi Trd<tng, khoa Vl)t Ly, trdi1ng D~i HQc Khoa HQc TV Nhit}n, D~i HQc Qu6c Gia TP.HCM. NgtfC1ihtf(1ng d~n khoa hQc: PGS. TS. IJt}Quang To~i PMn bit;n 1: PGS. TS.Dinh VAnu'u PMn bit;n 2: TS. Nguyen HOO NhAn PMn bit;n 3: TSKH. Phon VAnHoijc I j Lu~n an dtf<JcbaG vt? tnidc HQi B6ng chii'm lu~n an cii'p Nha Ntfdc, hQp t~i: tnt<'fngB<;tiHQc Khoa HQc Tt! Nhien TP.HCM VaGhie: 14 gi<'f30 ngay 24 thang 9 Dam 2004 C6 the am hieu lu~nan ~i thtfvit;n: ~ Khoa HQcT5ng H<JpTP.HCM - Tnt<'fngB<;tiHQc Kltoa HQc Tt! Nltien TP.HCM 1 M(1 DAU Khu v1!cbie'n yen 1XJDam Vi~t Nam c6 mQt vai tro ra-t quaDtrQngtrong nhi~u lanh v1!ckhac nhau. Cae nghi~n cll'u,khllo sat va do d~c cac d~c tntng hili dudng hQc ngay ding nhi~u hdn tr~n wng bien yen 1XJ.Tuy nhi~n, cac bai loan mo blah cho vung bie'nnay vancon tltdngd6i it.Cae qua trlnhtltdngtae bie'n-1XJ 1£1 nhfi'ng trd ng~i Idn eho cac bai loan mo blah. Ngoai fa, ding c6 the' ke' th~m blah d~ng du<'1ng1XJva s1!sii'd1}ngcac di~u ki~n bi~n d6i vdi mi~n tinh c6 bi~n rQng hudng v~ phia bie'n cling 1£1nhfi'ng kh6 khan kIDthi€t l~p mo blah. Phudng phap pMn tii'hfi'uh~n vdi tinh ~m deo trong vi~c thi€t k€ m~ng ludi to ra thich h~p d6i vdi khu v1!cc6 du<'1ng1XJ bie'n phrtc ~p, c6 nhi~u dao nM. M(ic du v&ntdn ~i nhfi'ngh~n ch€dang ke ciia n6 d6i vdi cae bai loan mo blah thiiy dQng11!c. Ngay nay, phudng phap pMn tii' hfi'u h~n dang du~c ap d1}ngngay cRag nhi~u hdn vao cac bai loan thiiy dQng 11!chQc bie'n, tU'nhfi'ngmo blah kich thudc nho, yen b<'1(lscandarani, 1993 - Le Provost, 1994 - Kapolnai, 1996) cho d€n cae bai toaD hoao hm d~i dttdng ba chi~u Dch thudc Idn (Greenberg, 1997). L~n lu~t cac bai toaD mQt,hai va ba chi~u thllYdQng 11!c hQc bien sii'd1}ngphudng phap phitn tii'hfi'u h~n du~c trlnh bay trong nQidung ciia lu~n an. Cung vdi vi~c ap d1}ngphudng phap so'tri ph~n tii'hfi'uh~n de' tinh toaDM th6ng hoan lttu gi6 mila ~i dai yen 1XJva th~m 11}c dia Dam Vi~t Nam, lu4n an nay con sii' d1}ngphudng phap tach mi~n khong giait cho bai toaDhoRnhm ba ehi~u. 2 A CHUdNG 1: TONG QUAN 1.1 GiO'ithi~u chung v~ khu vqc ven 1XIDamVi~t Nam Vung biin ven 1X7Dam Vi~t Nam du'<;1egidi h~n tit Nha Trang d6n dao Phd Qu6e du'QechQnlam khu vf{.enghi~n eU'u M th6ng dong ehiy trong cae thang gi6 mua (tMng 1 va thang 7) va cae thang gi6 chuyin mUa(thang 4 va thang 10). Khu vf{.enghi~n eU'uohm trong vUngkinh tuy6n tit 1O3~ d6n 111°Eva vi tuy6n tit 7,5~ d6n 13~. Df{.avao cae d~e diim v~ khi tu'Qngva hii van, ngu'Cfita ehia khu vf{.enay thanh ba vUng. Vung 1 tit Nha Trang d6n Viing Tau; vung 2 tit Viing Tau d6n Ca Mau va vung 3 lit vUngyen 1X7biin uty DambQ. 1.2 Cac nghi~n CUDh~ th6ng dong chsy ven I.XI Mc}t86 dQtkhao sat va do d~e dong ehiy yen 1X7tit cae tr~m do li~n t1;1edii du'Qeti6n hilnh. Trong d6 e6 thi ki d6n cae dQt "Dilu Ira khao sat tdng hf/p cae dilu ki~n tT!nhien t{li vung biin Kien Giang - CaMau" vitomua kho va mua mu'aDam1998 va ehuy6n khao sat vung biin Phan Thi6t vao thang 10/1999. 1.3 MOtviti m6 hJnh tinh toaD ng~n CUDBi~n D6ng Cae bili toaD mo hlnh eho vUngbiin yen bCfkhong nhi~u. Do d6, cae k6t qua tinh loan eua roOhlnh Biin Bong va vjnh Thai Lan eung ea'p nhii'ngthong tin eiin thi6t eho bili loan yen 1X7. Mc}ts6 k6t qua tu'dng tf{.nhau tit cae lac gia khae nhau. Ching h~n. mc}th~ th6ng dong eMy ~nh yen 1X7DamVi~t Nam tit Phan Thi6t d6n Ca Mau (vUng 1 va vUng2) hu'dngv~ Damtrong tru'Cfnggi6 mUa dong - Me va hu'dngl~n bifc trong tntCfnggi6 mua uty - nam; dong ehiy yen bCfvjnh Thai Lan (vUng3) pMt triin 3 ye'u trong tru'(Jnggi6 mila dong - Me nhu'ngpMt trieD ~nh trong tru'(Jng gi6 mila tay - Dam; 1.4 NQidung lu{in an va phddng phap nghi@ncoo 1.4.1 Cae n6i dung thu'cbien M11etieu chinh: tlnh toaD h<%th6ng dong chciy gi6 trung blnh hai chi~u va ba ehi~u khu v1f.eyen b(JDamVi<%tNam tll'Nha Trang de'n vnng bien tay Damva dao Phti Qu6c trong cae tru'(Jng gi6 mila d~c tru'ngbhng phu'dng pMp phin tit htru hc,tnvdi mc,tng lu'didu'~cxay d1f.ngg6m cae pMn to'tam ghic bit ky. Ngoai fa, phu'dngpMp phin tit htru hc,tncon du'~e ap d11ng vao bai toaDdong chay troi mQtchi~u vdi roOhlnh Ekman. Cae ke't qua tlnh toaDtru'£1ngdong chciytu'dng !tng vdi cae thang gi6 miIa d~c tru'ng va cae thang gi6 ehuyen mila du'~e th~ hi<%ntren cae ban d6. 1.4.2 Phu'dngpMp nghien eltu Mi~n tlnh yen b(Je6 bien long rit rQng. Phu'dngpMp tinh hai llin du'~e ap d11ng.LiD diu, vdi mi~n tlnh rQng hdn, khu vJ!.e nam Bi~n Bong. Ke't qua cua bai toan Dam Bi~n Bong du'~e sit d11nglam di~u ki<%nbien eho bai toaDyen b(J. Phu'dng pMp phin tit htru hc,tnd1f~eap d11ngd~ thJ!.Chi<%n dnh toaD eho cae bai toaD mQtchi~u, hai chi~u va ba chi~u. Cae mc,tnglu'di hai chi~u du'~exiiy d1f.ngteen cd sd phep dJ!.ngtam giae Delaunay, vdi thu~t toaDDelaunay Refinement. Phu'dng phap tach mi~n khong gian va phep bie'n ddi tQa dQ khong th!t nguyen sigma du'~c ap d11ngde tinh dong ehciyba chi~u. Bai toaD ba chi~u du'~e philn ra thanh cae bai toaD mQt ehi~u theo phu'dng thing d!tng va cae bai toaD hai ehi~u theo phu'dngngang. 4 CHUONG2:Cd Sa LY THuvET 2.1 H~ th6ng cae pbddng trlnb xua't pMt Hc$th6ng cae phu'dng trinh xu(t pMt mo ta cae hoan h.tu trong d~i du'dng bao gdm cae phu'dng trinh bio loan dQnghtc;Jng, bao loan kh6i htc;Jng,khue'ch tan mu6i va ehuy€n v~n entropi. B6i vdi nhung chuy~n dQng kich thu'deldn trong d~i du'dng,hc$th6ng phu'dng trinh xu(t pMt du'c;Jevie't trong hc$tQa dQe~u (A,(j),R) e6 d~ng r(t phtte ~p. 2.2 Cae phep xa'p xi Sa d~ng phep ehie'u leD ~t phing [3,cae phep g~n dung thuy tinh va phep g~n dung Boussinesq d€ du'a M cae phu'dng trinh xu't pMt v~ d~ng ddn gian hdn. 2.3 Cae m6 hlnb Hob toaD dong coy trong d{tidddng 2.3.1 Mo hlnh ba ehi~u Phu'dng trinh bio loan dQng 1u'c;Jngd6i vdi thanh phh thing drtng rut l~i thanh phu'dngtrinh thuy tinh va thanh pMn v~n t6e thing drtng du'c;Jetinh tit phu'dng trinh lien t~e. Cae phu'dng trinh chuy€n dQnge6 d~ng: 00 00 00 00 1 Op. ac. g a ~ / a ( 00 ) -+u-+v-+w fv= g jpdz+- A - +A Au Ot Ox. Oy Oz Po Ox. Ox. Po Ox.z Oz ZOz t Ov Ov Ov Ov 1 Op. ac. g a f ~ / a ( Ov ) -+u-+v-+w-+fu= g pdz+- A - +AtAv Ot Ox. Oy Oz Po Oy Oy Po Oy Z oz ZOz (2.1) Phu'dng trinh lien t~e d~ tinh thanh ph~n v~n t6e thing drtng: aw' au av - = az ax ay (2.2) 5 Thanh ph~n thing dli'ng eua veetd v~n t6e dong eMy t~i day bien Wbva dao dQng ro1,1'enUdel,;dli<;fCtinh tit cac di~u ki~n dQnghQc~i day bien va tren ~t bien: aH aH . Wb = -Ub Vb- khl z=-H ax ay al,; al,; al,; . -+u -+v - = W khl Z= r at sax Say S "" 2.3.2 Sli trung blnh h6a theo phlidng thing dli'ng va rod hlnh hai chi~u V~n t6c dong cMy trung blnh theo dQsdu dli<;fcdjnh nghia: 1 /; 1 /; 11= J udz v= J vdz (2.5) (H + l;LH (H + l;LH Tich pMn cac phu'dog trlnh (2.1) va (2.2) theo phu'dng thing dli'ng,ta c6 rod bloh hai chi~u: au au au 1 Cpa 8l; g /; /;api -a+U ax+v oy -fv=-p;:- ax -g ax- Po(H+l;) ifax dzdz+ 'tS 'tb + x x +Al~u Po(H+l;) Po(H+~) av av av 1 ape 8l; g J /; J /;api -at+uax +v ay +fu=- Po ay -gay PO(H+l;)-HZ ay dzdz+ 'ts 'tb + y y + A ~V l Po(H+l;) Po(H+l;) au(H + l;) + av(H + l;) + al; = 0 ax ay at 2.3.3 Phlidng phap pMn fa cua rod hloh ba chi~u C6 nhi~u phu'dng phap pMn fa rod hlob ba chi~u ohhro dlia bai toaDv~ d~og ddn giiin hdo. MQt troog 86 d6 la 81,1'tach cac thanhpMn nhroogangu va v cuadongcMy thanhcac thanhph~n (2.3) (2.4) (2.6) (2.7) (2.8) 6 dong chay trung blnh U,v va cac dQI~ch cua n6 Uf,v' quanh gia tri trung blnh: u=u+ui V=V+Vf (2.9) U,v duQcgQila cac thAnhpMn chInh ap cua dong chay va uf, v' duQCgQila cac thiinh ph~n ta ap. Thanh ph~n chInh ap cua dong chay U,v va dao dQngmlfc nudc ,duQctioo tU'mo hlnh hai chi~u. Cac thAnbpMn ta ap uf, v' duQc Hnhvdi budc th<'Jigian Idn bdn, c6 the ga'p mu<'JiI~n, so vdi budc th<'Jigian tinh cac thanh pMn chinh ap. 2.4 Trao d6i rffi thing dUng Thong thu<'Jng,ngu<'Jita danb gia M 86 trao d6i r6i th~ng dd'ngAztU'phudng trlnh dQngDangr6i: oE+uoE+voE+woE;:::A [( OU ) 2 + ( fJv ) 2 ] +~ ( A OE ) -!D oP-e at Ox Oy Oz Z Oz Oz oz ZOz P zoz (2.10) Trong sd dd Mellor - Yamadab~c2, cac M s6 traod6i r6i va khutch tan r6i duQc tlnh to' pbudng trlOOditng cua dQngmlng r6i: A{(:r+(:)'] -:D, :-e =0 (2.11) Trong 8d dd Mellor - Yamada b4c 2V2,1cichthudc r6i duQc tinh tU'phudng trlnb chuyen dQng: D(q2p)=~ ( K oq2P ) +EIPf Az [( 8u ) 2 + ( fJv ) 2 ] + ! Dz api } -e (2.12) Dt Oz q Oz 1 Oz oz Po oz - Cac h~ s6 trao d6i r6i Az.trao d5i khutch tan Dz: Az =lqSM Dz =lqSH' (2.13) 7 CHt1<1NG3: AP DVNG PHt1<1NG PHAP PRAN Tit HOO ~N VAo CAC MO HINH TiNH TOANDONGCHAY 3.1BMtoan m()tchi~u 3.1.1 Thi€t lap bAiloan Hc$th6ng cae ph\tdng trlnh xutt pMt eua bai toan m(>t ehi~u Ozmidov e6 dl;\ng: au fv at av -+fu at = ~(A au) az Z az = ~(A av) az Z az (3.1) (3.2) cae di~u kic$nbi~n: - Tl;\im~t biin eho tr\tde tr\t{Jng\fng Stitt tie'p tuye'n gi6 tr~n ~t biin: A au(z, t) - A av(z, t) - Po z az - 'tx Po Z az - 'ty - Tl;\iday biin vdi di~u kic$ndinh: u(-H) =v(-H) =0 va di~u kic$nban ddu: (3.3) (3.4) u(z,t=O)=0 va trongd6: u va v la cae thanhphdnohmngangeua v~nt&-edongehay. Sir d~ng ph\tdngpMp phdn ttl hii'uhl;\n,gia tri gdn dung eua cae thanhpMn v4n t6e dong ehay u va Y d\t<;1extp xi quanh cae nut eua phdntii': U -(1) - U <1>(1)+ U <1>(1) - 1 1 2 2 U-(n) - U <I>(n)+ U <I>(n) - N.l N+1 2 v(z,t=O) = 0 y(l) - v <1>(1)+ v <1>(1) - 1 1 2 2 - V (n) - V n,.(n) + v <I>(n) - N""'1 N+1 2 8 V.di c1>lk)va c1>r)la cae ham d~ng dng vdi ph~n ur (k): c1>lk) = zk+l-z va c1>~k)= Z - Zk (3.5) L L Ap d\lDg phtidng phap Galerkin. m3i pUn td' dti<;Jebi~u di~n dtfdi ma tr~n: [ L/ 3 L/ ]{ ~ J i -A ~~I+A (Uhl-Uk) + Lf ( Vk + Vk+l )) /3 16 Uk - zfulk zk L 3 6 L/ LI ~ - A ~ u -A (Uk+l-U\::)+ Lf ( VI:: + VI::+l ) /6 13 Uk+l Zoz zk L 6 3 .1::+1 [ L/ 3 L/ jl ~ \ i -A ov-I +A (Vk+l-VI<) Lf ( UI:: + Uhl )! 7316 Vk - zOZlk zk L 3 6 (3.6) L/ L/ ~ - A Ov l -A (Vk+l-Vk)-Lf ( Uk+Uk+l ) /6 13 Vk-l z OZ zk L 6 3 1<+1 San khi lien ke't ta't ea cae pUn tU'd~ ~o thanh m<}tma tr~n loan eve cho ml,tng ltidi. ta dti<;Jchai M phtidng trlnh dnh cae thAnh ph~n v~ r t6e u va v rieng bi~t e6 dl,t ~ ~hti san: [A] U}={Bu} va [A] VJ={BJ (3.7) Dtfa c c ai€u ki~n bien vao M (3. ) va chung dti<;Jcgiiii bhng sai philn tie'n theo thCligian dng vdi mMbtide l~p. 3.1.2 Cae ke't qua cua bai loan mot chi€u 1. TrtiClngdng sua't tie'p tuye'n gi6 kMng d5i: ke't qua tinh toaD nMn dti<;JedtiClngxoAn 6e Ekman dng v"i cae vi de] khae nhau 2. TrtiClngh<;JptrtiClngdng sua't tie'p tuye'n gi6 thong d5i phtidng va de]!dn bie'n thien di€u bOa:cae kh6i nti"e l~i loon xoay htidng eung chu ky eua trtiClnggi6. eung chi€u kim d6ng h6 d BAc Ban C~u va ngti<;Jcl~i ~i Nam Ban C~u. [...]... a1uol 1 al a1u/ 1 a1ul -att= (H+ . Op. ac. g a ~ / a ( 00 ) -+ u-+v-+w fv= g jpdz +- A - +A Au Ot Ox. Oy Oz Po Ox. Ox. Po Ox.z Oz ZOz t Ov Ov Ov Ov 1 Op. ac. g a f ~ / a ( Ov ) -+ u-+v-+w-+fu= g pdz +- A - +AtAv Ot Ox. Oy Oz Po Oy. d~ng: ou ou OU at;, 1:~ 1:~ ( 3 8 ) -+ u-+v fv = -g-+ - +A,dU' ot ox oy ox pQ(H+t;,) Po(H+ t;,) s b ov ov ov tJ(, 'y 'y (3 9) -+ u-+v-+fu=-g-+ - +AfJ)v, ot ox oy oy Po(H+(,) Po(H+(,) 10 ou(H+l;;). xua't pMt co d!,og: Ou+uOu+vOu+wOu-fv=-got;-JL~lpldz+~ ( A au ) +A Llu at Ox Oy oz ox PoOxz f}z z& £ av av av av at; g 0 7- I 0 ( av ) -+ u-+v-+w-+fu=-g jpdz +- A - +A Llv at Ox Oy f}z oy PoOy