Mecánica de Fluidos

95
 058:0160 Chapters 3 & 4 Professor Fred Stern Fall 2006 1 Chapters 3 & 4: Integral Relatio ns for a Control ol!"e and #ifferential Relations for Fl!id Flo$

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Mecánica de Fluidos

Transcript of Mecánica de Fluidos

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    058:0160 Chapters 3 & 4

    Professor Fred Stern Fall 2006 1

    Chapters 3 & 4: Integral Relations for a Control ol!"e

    and #ifferential Relations for Fl!id Flo$

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    Re%nolds ransport heore" 'R(

    )eed relationship *et$een ( )sysBdtd

    and +hanges in

    ==CVCV

    ddmcvB ,

    1 - ti"e rate of +hange of . in C - =CV

    ddt

    d

    dt

    cvdB

    2 - net o!tfl!/ of . fro" C a+ross CS -

    R

    CS

    V n dA

    dAnVddt

    d

    dt

    dBR

    CSCV

    SYS +=

    eneral for" R for "oing defor"ing +ontrol ol!"e

    Spe+ial Cases:

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    1( )ondefor"ing C "oing at +onstant elo+it%

    ( ) dAnVdtdt

    dBR

    CSCV

    SYS +=

    2( Fi/ed C

    ( ) dAnVdtdt

    dB

    CSCV

    SYS +=

    reens heore":CV CS

    b d b n dA =

    ( ) ( )

    +

    = dVtdt

    dB

    CV

    SYS

    Sin+e C fi/ed and ar*itrar% 0li"d gies differential e,

    3( Stead% Flo$: 0=

    t

    4( nifor" flo$ a+ross dis+rete CS 'stead% or !nstead%(

    =CSCS

    dAnVdAnV (- inlet, + outlet)

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    Contin!it% !ation:

    . - - "ass of s%ste"

    7 - 1

    0=dt

    dM*% definition s%ste" - fi/ed a"o!nt of "ass

    Integral For":

    dAnVddt

    d

    dt

    dM

    CS

    R

    CV +== 0

    dAnVddt

    d

    CS

    R

    CV

    =

    Rate of decrease of mass in CV net rate of mass outflo! across CS

    )ote si"plifi+ations for nondefor"ing C fi/ed Cstead% flo$ and !nifor" flo$ a+ross dis+rete CS

    In+o"pressi*le Fl!id: 9 - +onstant

    dAnVddt

    d

    CS

    R

    CV

    =

    +onseration of ol!"e;

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    Spe+ial +ase C for" +ontin!it% e!ation:

    Fi/ed C

    0CV CS

    d V n dAt

    + = and !nifor" flo$ oer dis+rete inlet

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    Professor Fred Stern Fall 2006 =

    0

    1=

    +

    +

    +

    unit$erc%an&eofrate

    '

    !

    y

    v

    (

    u

    V

    unit$er

    c%an&eofrate

    #t

    #

    Called the +ontin!it% e!ation sin+e the i"pli+ation is that

    9 and Vare +ontin!o!s f!n+tions of /,

    In+o"pressi*le Fl!id: 9 - +onstant

    0

    0

    =

    +

    +

    =

    '

    !

    y

    v

    (

    u

    V

    P3,15 >ater ass!"ed in+o"pressi*le flo$s steadil%thro!gh the ro!nd pipe in Fig, P3,15, he entran+e

    elo+it% is +onstant 0u )= and the e/it elo+it%

    appro/i"ates t!r*!lent flo$ ( )1 =

    "a/ 1u u r R= , #eter"ine

    the ratio "a/) u for this flo$,

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    Stead% flo$ nondefor"ing or "oing C one inlet

    !nifor" flo$ and one o!tlet non!nifor" flo$( )

    1 =2

    0 "a/0

    0 1 2R

    ) R u r R rdr = + 2 2

    0 "a/

    4?0

    60) R u R

    = +

    0

    "a/

    4?

    60

    )

    u=

    ( ) ( )15 =

    "a/ "a/0

    2 2

    1 12 2 1 1

    1 12 1

    = =

    R

    u rdr u r R r R

    R R

    =

    + +

    2

    "a/

    = =2 0

    15 8u R

    = 2

    "a/4?260

    u R=

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    P3,12 he pipe flo$ in Fig, P3,12 fills a +%lindri+al tan@

    as sho$n, At ti"e t-0 the $ater depth in the tan@ is

    30+", sti"ate the ti"e re!ired to fill the re"ainder of

    the tan@,

    nstead% flo$ defor"ing C one inlet one o!tlet

    !nifor" flo$

    1 20CV

    dd " "

    dt = +

    2 2

    1 20 4 4CV

    d d d

    d V Vdt

    = +( ) ( )

    2

    4

    #t % t

    =

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    ( )2 2

    2 104 4

    # d% dV V

    dt

    = +

    ( )

    2

    2 1 0,0153d% d V Vdt # = =

    0,=46

    0,0153 0,0153

    d%dt s= = =

    Stead% flo$ one inlet and t$o e/its $ith !nifor" flo$

    1 2 30 " " "= + +

    ( )2

    3 1 2 1 24

    d" " " V V

    = =

    ( )

    2

    2

    1 2

    4

    4

    #d%

    dtd"

    V V

    = =

    ( )

    2

    1 2

    #d%d

    V V

    =

    3

    A

    *" V n dA

    s=

    ol!"e of fl!id per !nit ti"e thro!gh A

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    P4,1= A reasona*le appro/i"ation for the t$o

    di"ensional in+o"pressi*le la"inar *o!ndar% la%er on

    the flat s!rfa+e in Fig,P4,1= is

    2

    2

    2y yu )

    = for

    y

    $here 1 2C(= C const='a( Ass!"ing a noslip +ondition at the $all find an

    e/pression for the elo+it% +o"ponent ( )v ( y for y ,'*( he find the "a/i"!" al!e of v at the station 1( m= for the parti+!lar +ase of flo$ $hen 3) m s= and

    1,1cm= ,

    0u v( y

    + =

    ( )2 2 32 2v u

    ) y yy ( (

    = = +

    ( )2 2 30

    2y

    (v ) y y dy =

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    'a(2 3

    2 32

    2 3(

    y yv )

    =

    1 2

    C(= 1 22 2

    (

    C(

    (

    = =

    '*( Sin+e 0yv = at y =( )"a/

    2 1 1

    2 2 3

    )v v y

    (

    = = =

    3 1,10,0055

    6 6

    )m s

    (

    = = =

    o"ent!" !ation:

    . - V- "o"ent!" 7 - V

    Integral For":

    {

    ' (

    31 2

    R

    CV CS

    d MV d V d V V n dA +

    dt dt

    = + = 1 4 2 4 3 1 44 2 4 43

    + - e+tor s!" of all for+es a+ting on C

    - F.B Fs

    F.- .od% for+es $hi+h a+t on entire C of fl!id d!e

    to e/ternal for+e field s!+h as grait% or

    ele+trostati+ or "agneti+ for+es, For+e per !nit

    ol!"e,

    Fs- S!rfa+e for+es $hi+h a+t on entire CS d!e to

    nor"al 'press!re and is+o!s stress( and

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    tangential 'is+o!s stresses( stresses, For+e per

    !nit area,

    >hen CS +!ts thro!gh solids Fs"a% also in+l!de FR-

    rea+tion for+es e,g, rea+tion for+e re!ired to hold nole

    or *end $hen CS +!ts thro!gh *olts holding nolehere ( ) V

    V Vt t t

    = +

    andDD D

    V V VV ui V v,V !- V = = + + is a tensor' ( ' ( ' ( ' ( ' (V V VV uV vV !V

    ( y '

    = = + +

    VVVV += ('

    - 0 +ontin!it%

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    ( )CV

    VV V V V d +

    t t

    + + + =

    Sin+eV #V

    V Vt #t

    + =

    = +d#t

    V#

    CV

    = f#t

    V# $er elemental fluid volume

    sbffa +=

    bf - *od% for+e per !nit ol!"e

    sf - s!rfa+e for+e per !nit ol!"e

    .od% for+es are d!e to e/ternal fields s!+h as grait% or

    "agneti+ fields, Eere $e onl% +onsider a graitational

    field that isd(dyd'&+d+

    &ravbody = =

    and D& &-= for

    i,e, Dbody

    f &-=

    S!rfa+e For+es are d!e to the stresses that a+t on the sides

    of the +ontrol s!rfa+es

    i,i,i, $ +=

    ++

    +=

    '''y'(

    y'yyy(

    ('(y((

    $

    $

    $

    is+o!s stre)or"al press!re

    g

    S%""etri+ i, ,i =

    2ndorder tensor

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    As sho$n *efore for p alone it is not the stresses

    the"seles that +a!se a net for+e *!t their gradients,

    S%""etr% +ondition fro" re!ire"ent that for ele"ental

    fl!id ol!"e stresses the"seles +a!se no rotation,

    fff

    $s+=

    Re+all $f$ = *ased on 1storder S, f is "ore +o"ple/

    sin+e i, is a 2ndorder tensor *!t si"ilarl% as for p the

    for+e is d!e to stress gradients and are deried *ased on

    1storder S,

    GGG

    GGG

    GGG

    -,i

    -,i

    -,i

    '''y'('

    y'yyy(y

    ('(y(((

    ++=

    ++=

    ++=

    ' ( ' ( ' (s ( y '+ d(dyd'( y '

    = + +

    Res!ltant stress

    on ea+h fa+e

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    ' ( ' ( ' (( y 'sf

    ( y '

    = + +

    and si"ilarl% for

    G' ( ' ( ' (

    G' ( ' ( ' (

    G' ( ' ( ' (

    (( y( '(s

    (y yy 'y

    (' y' ''

    f i( y '

    ,( y '

    -( y '

    = + +

    + + +

    + + +

    i, i,s,

    f(

    = =

    /

    %

    dyd'd((

    ((

    ((

    +

    y(

    y( dy d(d'y

    +

    y(d(d'

    ((dyd'

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    ' ( ' ( ' (

    ' ( ' ( ' (

    ' ( ' ( ' (

    s( (( (y ('

    sy y( yy y'

    s' '( 'y ''

    f( y '

    f ( y '

    f( y '

    = + +

    = + +

    = + +

    P!tting together the a*oe res!lts

    Di,

    #Va &-

    #t

    = = +

    )e/t $e need to relate the stresses Hito the fl!id "otion

    i,e, the elo+it% field, o this end $e e/a"ine the

    relatie "otion *et$een t$o neigh*oring fl!id parti+les,

    J .: VdrVdVV +=+ 1storder a%lor Series

    ,i,

    'y(

    'y(

    'y(

    d(e

    d'

    dy

    d(

    !!!

    vvv

    uuu

    VdrdV =

    ==

    *od% for+e d!e

    to grait%"otion

    s!rfa+e for+e - p B is+o!s ter"s

    'd!e to stress gradients(

    .

    A '!$( - V

    relatie "otion defor"ation rate

    tensor - i,e

    dr

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    1 1

    2 2

    , ,i i ii, i, i,

    , , i , i

    u uu u ue

    ( ( ( ( (

    symmetric $art anit symmetric $arti, ,i i, ,i

    = = + + = +

    = =

    1 442 4 43 1 442 4 43

    1 10 ' ( ' (

    2 2

    1 1' ( 0 ' (

    2 2

    1 1' ( ' ( 0

    2 2

    y ( ' (

    i, ( y ' y

    ( ' y '

    u v u !

    v u v ! ri&id body rotation

    of fluid element

    ! u ! v

    = =

    6 47 48

    142 43

    1 42 43

    !%ere rotation about ais rotation about y ais. rotation about ' ais

    )ote that the +o"ponents of iare related to the orti+it%e+tor define *%:

    DD D' ( ' ( ' (

    2 22

    y ' ' ( ( yV ! v i u ! , v u -

    = = + + 14 2 4314 2 43 14 2 43

    - 2 ang!lar elo+it% of fl!id ele"ent

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    1 1' ( ' (

    2 2

    1 1' ( ' (

    2 2

    1 1' ( ' (

    2 2

    i,

    ( y ( ' (

    ( y y ' y

    ( ' y ' '

    rate of strain tensor

    u u v u !

    v u v v !

    ! u ! v !

    =

    + +

    = + + + +

    ( y 'u v ! V + + = - elon&ation (or volumetric dilatation)

    of fluid element

    1 #

    #t

    =

    ('2

    1(y

    vu + - distortion $rt '/%( plane

    ('2

    1('

    !u + - distortion $rt '/( plane

    ('2

    1y'

    !v + - distortion $rt '%( plane

    h!s general "otion +onsists of:

    1( p!re translation des+ri*ed *% V

    2( rigid*od% rotation des+ri*ed *% K /

    3( ol!"etri+ dilatation des+ri*ed *% V

    4( distortion in shape des+ri*ed *% i i

    It is no$ ne+essar% to "a@e +ertain post!lates +on+erning

    the relationship *et$een the fl!id stress tensor 'Hi( andrateofdefor"ation tensor 'ei(, hese post!lates are

    *ased on ph%si+al reasoning and e/peri"ental

    o*serations and hae *een erified e/peri"entall% een

    for e/tre"e +onditions, For a )e$tonian fl!id:

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    1( >hen the fl!id is at rest the stress is h%drostati+ and

    the press!re is the ther"od%na"i+ press!re

    2( Hiis linearl% related to eiand onl% depends on ei,

    3( Sin+e there is no shearing a+tion in rigid *od%

    rotation it +a!ses no shear stress,

    4( here is no preferred dire+tion in the fl!id so thatthe fl!id properties are point f!n+tions '+ondition of

    isotrop%(,

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    sing state"ents 13

    i,i,mni,i, -$ +=

    imn- 4thorder tensor $ith 81 +o"ponents s!+h that ea+h

    stress is linearl% related to all nine +o"ponents of Li,

    Eo$eer state"ent '4( re!ires that the fl!id has no

    dire+tional preferen+e i,e, Hiis independent of rotation of

    +oordinate s%ste" $hi+h "eans imnis an isotropi+ tensor- een order tensor "ade !p of prod!+ts of 0i,

    i,mn i, mn im ,n in ,m- = + +

    scalars=('

    Mastl% the s%""etr% +ondition Hi - Hire!ires:

    @i"n- @i"n N - O - is+osit%

    {2i, i, i, mm i,$

    V

    = + +

    and O +an *e f!rther related if one +onsiders "ean

    nor"al stress s, ther"od%na"i+ p,

    3 '2 3 (ii

    $ V = + +

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    1 2

    3 3ii$ V

    $ mean

    normal stress

    = + +

    =123

    2

    3$ $ V

    = +

    In+o"pressi*le flo$: $$= and a*sol!te press!re is

    indeter"inant sin+e there is no e!ation of state for p,

    !ations of "otion deter"ine $ ,

    Co"pressi*le flo$: $$ and - *!l@ is+osit% "!st *e

    deter"ined ho$eer it is a er% diffi+!lt "eas!re"ent

    re!iring large1 1# #

    V#t #t

    = =

    e,g, $ithin sho+@

    $aes,

    Sto@es E%pothesis also s!pported @ineti+ theor%

    "onotoni+ gas,

    $$=

    = 3

    2

    2 23

    i, i, i,$ V = + + eneraliation dy

    du= for 3# flo$,

    +

    =i

    ,

    ,

    i

    i,

    (

    u

    (

    u ,i relates s%ear stress to strain rate

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    2 12 2

    3 3

    i iii

    i i

    u u$ V $ V

    ( (

    normal viscous stress

    = + = + + 1 4 442 4 4 43

    >here the nor"al is+o!s stress is the differen+e *et$een

    the e/tension rate in the /i dire+tion and aerage

    e/pansion at a point, Qnl% differen+es fro" the aerage -

    +

    +

    '

    !

    y

    v

    (

    u

    3

    1 generate nor"al is+o!s stresses, For

    in+o"pressi*le fl!ids aerage - 0 i,e, 0V = ,

    )on)e$tonian fl!ids:

    i,i, for s"all strain rates

    $hi+h $or@s $ell for

    air $ater et+, )e$tonian fl!ids

    { {

    ni, i, i,

    tnon linear %istory effect

    +

    )on)e$tonian

    is+oeslasti+ "aterials

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    )on)e$tonian fl!ids in+l!de:

    '1( Pol%"ers "ole+!les $ith large "ole+!lar

    $eights and for" long +hains +oiled together

    in spong% *all shapes that defor" !nder shear,

    '2( "!lsions and sl!rries +ontaining s!spended

    parti+les s!+h as *lood and $ater

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    22 22

    ,i i

    i, i

    , , , i , ,

    uu uu V

    ( ( ( ( ( (

    = + = = =

    For in+o"pressi*le flo$ 0V =

    2D

    D D

    #V&- $ V

    #t$ !%ere $ $ '

    $ie'ometric $ressure

    = +

    = +1 42 43

    For O - 0

    D#V & - $#t

    = !ler !ation

    )S e!ations for 9 O +onstant

    2D#V $ V#t

    = +

    2D#V

    V V $ V #t

    + = +

    1on-linear 2ndorder 3#4, as is t%e case for 5, 6 not constant

    Co"*ine $ith V for 4 e!ations for 4 !n@no$ns V pand +an *e al*eit diffi+!lt soled s!*e+t to initial and

    *o!ndar% +onditions for V p at t - t0and on all

    *o!ndaries i,e, $ell posed; I.P,

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    Appli+ation of C o"ent!" !ation:

    RCV CS

    d

    + V d V V n dAdt = +

    SB +++ += 'in+l!des rea+tion for+es(

    )ote:

    1, e+tor e!ation

    2, n - o!t$ard !nit nor"al: RV n 0 inlet 0 o!tlet

    3, 1# o"ent!" fl!/

    ( ) ( )i ii iout inCS

    V V n dA m V m V =

    & &

    >here iV i are ass!"ed !nifor" oer dis+rete inlets

    and o!tlets

    i i ni im V A=&

    { ( ) ( )i ii i inout

    CV

    d+ V d m V m V

    dtnet force inlet momentumoutlet momentum

    time rate of c%an&eonCV flu(flu(of momentum in CV

    = + & &1 42 431 4 2 4 31 4 2 4 3

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    4, o"ent!" fl!/ +orrelation fa+tors

    2 2

    avu V n dA u dA AV

    a(ial flo! !it%non uniformvelocity $rofile

    = =

    14 2 43

    >here

    2

    1

    avCS

    udA

    A V

    =

    1av

    CS

    "V u dA

    AA= =

    Ma"inar pipe flo$:

    12

    2

    0 021 1r r

    u ) )R R =

    0,53avV )= 34=

    !r*!lent pipe flo$:

    m

    R

    r)u = 10 1 1? 5

    m

    ( )0

    2

    1 '2 (avV )

    m m=

    + + =1=m Vav 7829

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    ( ) ( )

    (22('21'2

    21 22

    mm

    mm

    ++++= m:;< = :792

    5, Constant p +a!ses no for+e herefore

    se pgage- pat"pa*sol!te

    0$CS CV

    + $n dA $ d= = = for p - +onstant

    6, At et e/it to at"osphere pgage- 0,

    =, Choose C +aref!ll% $ith CS nor"al to flo$ and

    indi+ating +oordinate s%ste" and +on C si"ilar

    as free *od% diagra" !sed in d%na"i+s,

    8, an% appli+ations !s!all% $ith +ontin!it% and

    energ% e!ations, Caref!l pra+ti+e is needed for"aster%,

    a, Stead% and !nstead% deeloping and f!ll%

    deeloped pipe flo$

    *, "pt%ing or filling tan@s

    +, For+es on transitions

    d, For+es on fi/ed and "oing anes

    e, E%dra!li+ !"p

    f, .o!ndar% Ma%er and *l!ff *od% drag

    g, Ro+@et or et prop!lsion

    h, )ole

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    058:0160 Chapters 3 & 4

    Professor Fred Stern Fall 2006 2?

    i, Propeller

    , >aterha""er

    First relate !"a/to 0!sing +ontin!it% e!ation

    ( ) += R m

    drrRruR)

    0"a/

    2

    0 210

    ( )0 "a/20

    11 2

    Rm

    avr) u r dr V

    RR

    = =

    T

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    058:0160 Chapters 3 & 4

    Professor Fred Stern Fall 2006 30

    "a/

    2

    '1 ('2 (av

    V um m

    =+ + " - 1

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    Professor Fred Stern Fall 2006 31

    22

    0

    2

    21 02,(' R)R$$+

    turb =

    Re+onsider the pro*le" for f!ll% deeloped flo$:

    Contin!it%:

    0in out

    in out

    m m

    m m m

    + == =

    & &

    & & & or U - +onstant

    o"ent!":

    2

    1 2

    1 1 2 2

    2 1

    ' (

    ' ( ' (

    ' (

    0

    (+ $ $ R + uV A

    u u A u u A

    " u u

    = =

    = +=

    =

    ( ) 21 2 2 0!$

    $ $ R R (

    =14 2 43

    =

    d(

    d$R!

    2 or for s"aller C r R

    =

    d(

    d$r

    2

    (valid for laminar or turbulent flo!, but assume laminar)

    ===

    d(

    d$r

    dr

    du

    dy

    du

    2 % - Rr '!all coord7)

    =

    d(

    d$r

    dr

    du

    2

    Co"plete anal%sis

    !sing CF#V

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    058:0160 Chapters 3 & 4

    Professor Fred Stern Fall 2006 32

    cd(

    d$ru +

    =

    4

    2

    0(' ==Rru

    = d(d$R

    c 4

    2

    =

    d

    d$rRru

    4('

    22

    =

    d(

    d$Ru

    4

    2

    "a/

    =

    2

    2

    "a/ 1('

    R

    ruru

    ==

    d(

    d$Rdrrru"

    R

    82('

    4

    0

    2

    "a/

    28ave

    " R d$ uV

    A d(

    = = =

    2

    8 4

    2 2

    ave ave!

    V VR d$ R

    d( R R

    = = =

    2

    8 32 64 64

    Re

    !

    ave ave ave

    fV RV V #

    = = = =

    Re aveV #

    =

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    /a+t sol!tion of )S for la"inar f!ll% deeloped pipe

    flo$

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    058:0160 Chapters 3 & 4

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    a@ing "oing C at speed s- WR X en+losing et and

    *!+@et:

    Contin!it%: 0in out m m + =& &

    Rin out

    CS

    m m m V n dA= = = & & &

    Inlet DR ,V V R n i= =

    Q!tlet G' (R ,V V R n i= =

    o"ent!":

    > buc-et out in+ + mu mu= = & &

    2

    ' ( ' (

    2 ' (

    2 ' (

    buc-et , ,

    ,

    , ,

    + m V R V R

    m V R

    A V R

    =

    =

    =

    &

    ' (, ,m A V R

    =

    22 ' (buc-et , ,

    3 R+ A R V R= =

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    Professor Fred Stern Fall 2006 35

    0=d

    d3 for

    3

    ,VR = 3"a/

    8

    2= , ,

    3 A V=

    If infinite n!"*er of *!+@ets: , ,m A V=&

    3

    "a/

    2 ' (

    2 ' (

    10

    2 2

    buc-et , , ,

    , , ,

    ,

    , ,

    + A V V R

    3 A V R V R

    Vd3for R 3 A V

    d

    =

    =

    = = =

    C +ontin!it% e!ation for stead% in+o"pressi*le flo$

    one inlet and o!tlet A - +onstant

    in out

    V ndA V ndA m " = = = &

    in out " "=

    ( ) ( )ave avein out V A V A=

    For A - +onstant ( ) ( )ave avein out V V=

    ( ) ( )in out

    + V V n dA V V n dA = + Pipe:

    ( ) ( )(in out

    + u V n dA u V n dA = + ( ) ( )2 2ave ave

    in out AV AV = +

    ( )ave out in"V = +hange in shape !

    all et "ass flo$

    res!lt in $or@,

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    ane:

    ( )out in out in+ m V V V V= = &

    ( ) ( )2( out in in+ m u u m u= = & &

    +hange in dire+tion !

    Appli+ation of differential "o"ent!" e!ation:

    1, )S alid *oth la"inar and t!r*!lent flo$ ho$eer

    "an% order of "agnit!de differen+e in te"poral and

    spatial resol!tion i,e, t!r*!lent flo$ re!ires er%s"all ti"e and spatial s+ales

    2, Ma"inar flo$ Re+rit-)

    1000

    Re Re+rit insta*ilit%

    3, !r*!lent flo$ Retransition 10 or 20 Re+rit

    Rando" "otion s!peri"posed on "ean +oherent

    str!+t!res,

    Cas+ade: energ% fro" large s+ale dissipates at

    s"allest s+ales d!e to is+osit%,Yol"ogoro h%pothesis for s"allest s+ales

    4, )o e/a+t sol!tions for t!r*!lent flo$: RA)S #S

    MS #)S 'all CF#(

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    Professor Fred Stern Fall 2006 3=

    5, 80 e/a+t sol!tions for si"ple la"inar flo$s are

    "ostl% linear 0V V =

    a, Co!ette flo$ - shear drien

    *, Stead% d!+t flo$ - Poise!ille flo$

    +, nstead% d!+t flo$

    d, nstead% "oing $alls

    e, As%"ptoti+ s!+tion

    f, >inddrien flo$sg, Si"ilarit% sol!tions, et+,

    6, Also "an% e/a+t sol!tions for lo$ Re Sto@es and

    high Re .M appro/i"ations

    =, Can also !se CF# for non si"ple la"inar flo$s

    8, AF# or CF# re!ires $ell posed I.P therefore

    e/a+t sol!tions are !sef!l for set!p of I.P ph%si+s

    and erifi+ation CF# sin+e "odeling errors %ield

    S- 0 and onl% errors are n!"eri+al errors S)

    i,e, ass!"e anal%ti+al sol!tion - tr!th +alled

    anal%ti+al *en+h"ar@

    M'(-M'(-MA'A(-0 si"ilarl% for IC&.C

    ZS- S [ - ZS)B ZS

    S2- S)

    2B S2

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    Professor Fred Stern Fall 2006 38

    nerg% !ation:

    . - - energ%

    7 - e - d

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    058:0160 Chapters 3 & 4

    Professor Fred Stern Fall 2006 3?

    vd? dA V = & - viscous force velocity

    v

    CS? V dA=

    &

    ( )' (

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    058:0160 Chapters 3 & 4

    Professor Fred Stern Fall 2006 40

    #efine @ineti+ energ% +orre+tion fa+tor

    32

    21' (2 2

    ave

    aveA A

    VVdA V V n dA mA V

    = =

    Ma"inar flo$:

    =

    2

    0 1

    R

    r)u

    Vave97A = ; D2

    !r*!lent flo$:m

    R

    r)u

    = 1

    0

    ( ) ( )3 3

    1 2

    4'1 3 ('2 3 (

    m m

    m m

    + +=

    + +

    m:;< D:79A8 as !it% =, DE: for

    turbulent flo!

    2 2

    D D' < ( ' < (2 2

    s ave aveout in

    ? V V"u $ &' u $ &'

    m m = + + + + + +

    & &

    & &

    Met in - 1 o!t - 2 V- Vae and diide *% g

    2 21 1 2 21 1 2 2

    2 2$ t *

    $ $V ' % V ' % %

    & & & &

    + + + = + + + +

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    058:0160 Chapters 3 & 4

    Professor Fred Stern Fall 2006 41

    $s tt $

    ?? ?% %

    &m &m &m= =

    && &

    & & &

    2 1

    1' (

    *

    "% u u

    & m&=

    &

    &

    %* t%ermal ener&y (ot%er terms re$resent mec%anical ener&y

    1 1 2 2m AV A V = =&

    Ass!"ing no heat transfer "e+hani+al energ% +onerted

    to ther"al energ% thro!gh is+osit% and +an not *e

    re+oered therefore it is referred to as head loss 0

    $hi+h +an *e sho$n fro" 2ndla$ of ther"od%na"i+s,

    1# energ% e!ation +an *e +onsidered as "odified.erno!lli e!ation for hpht and hM,

    Appli+ation of 1# nerg% e!ation f!ll% deeloped pipe

    flo$ $itho!t hpor ht,

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    058:0160 Chapters 3 & 4

    Professor Fred Stern Fall 2006 42

    1 21 2

    2

    2

    ' ( ' (

    2

    1

    8

    2

    *

    ! !

    ave

    ave*

    $ $ * d% ' ' $ ' * d(

    & & d(

    *f& R

    V

    V*% f

    # &

    = + = + =

    = =

    =

    For la"inar flo$

    2

    8 32!

    ave ave

    fV RV

    = =

    2

    32 ave*

    *V%

    #

    = Vae e/a+t sol!tionV

    For t!r*!lent flo$ Re+rit ] 2000 Retrans] 3000

    f-f 'Re @

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    058:0160 Chapters 3 & 4

    Professor Fred Stern Fall 2006 43

    %* %f+ F%m $here

    2

    2m

    V% @

    &

    @ loss coefficient

    =

    =

    h"- so +alled; "inor losses e,g, entran+e

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    058:0160 Chapters 3 & 4

    Professor Fred Stern Fall 2006 44

    .erno!lli negle+t g p2-pa2 2

    1 1 2 2

    1 1

    2 2$ V $ V + = + %*9, 'constant

    ( )2 21 2 2 11

    2$ $ V V= + 2 21

    ,=? ??8101 000 '5,22 2,0? (2

    $ = +

    1 110020$ 3a=

    )ote: 2 2 2

    2 2 3 3 4 42 2 2

    $ V $ V $ V

    + = + = +

    2 3 4 2 3 4a$ $ $ $ V V V= = = = =

    2 2 3 3 4 40CS

    V A A V A V A V = = +432

    AAA +=

    3 3 3 4 4 40 ' (yCS

    + VV A V V A V V A = = = + 2 2

    3 3 4 4V A V A = 43 AA =

    '*( For the ro!nd et gien in the pro*le" state"ent

    2 2

    2 2

    2

    ,=? ?8? ,02 4254

    (+ + mV V 1

    A

    = = = & 142 43

    12 3

    2 41,4 < 10,3

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    058:0160 Chapters 3 & 4

    Professor Fred Stern Fall 2006 45

    Contin!it% e!ation *et$een points 1 and 22

    21 1 2 2 1 2

    1

    #V A V A V V

    #

    = =

    2

    1

    241,4

    5V

    =

    1 6,63

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    058:0160 Chapters 3 & 4

    Professor Fred Stern Fall 2006 46

    'a(2

    21 2

    2

    V' '

    &= + 01101 212 ==== ''%*

    2 1 22 ' (V & ' ' = 11_81,?_2= sm

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    Professor Fred Stern Fall 2006 4=

    '+(

    2 2

    2 21 2 2

    2 2

    V V*' ' f

    & # &= + + D2:

    ( )2

    21 2 1 here ( )i,#V

    V V & V #t

    =

    D' ( ii,

    ,

    ii,

    ,

    u#u- J

    #t (

    u$ V

    (

    = +

    1 2 3

    D' < ( ' ( 0ii,,

    u# #$u $ - J dissi$ation function

    #t #t (

    + = + + =

    123

    ++=#t#$J-

    #t#% ('

    S!""ar% # for +o"pressi*le non+onstant propert%

    fl!id flo$

    Cont, ' ( 0Vt

    + =

    o", i,#V

    & $#t

    = +

    D

    i, i, i,V

    & &-

    = +

    =

    ' < ($ # #

    $#t #t

    = +

    "o"ent!" e!ation

    +ontin!it% e!ation

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    058:0160 Chapters 3 & 4

    Professor Fred Stern Fall 2006 50

    nerg% ++= (' J-#t#$

    #t

    #%

    Pri"ar% aria*les: p V

    A!/iliar% relations: 9 - 9 'p( O - O 'p(

    h - h 'p( @ - @ 'p(

    Restri+tie Ass!"ptions:

    1( Contin!!"2( )e$tonian fl!ids

    3( her"od%na"i+ e!ili*ri!"

    4( f - 9g D-

    5( heat +ond!+tion follo$s Fo!rier`s la$

    6( no internal heat so!r+es

    For in+o"pressi*le +onstant propert% fl!id flo$

    Dvdu c dJ = cv, 6, , 5 E constant

    += J-#t

    #Jc

    v

    2

    For stati+ fl!id or Vs"all

    J-t

    Jc

    $

    2=

    %eat conduction eIuation (also valid for solids)

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    Professor Fred Stern Fall 2006 51

    S!""ar% # for in+o"pressi*le +onstant propert% fl!id

    flo$ '+] +p(

    0V =

    2D#V &- $ V#t

    = + ellipti+;

    += J-#t

    #Jc

    $

    2 $here,

    i

    i,

    (

    u

    =

    Contin!it% and "o"ent!" !n+o!pled fro" energ%

    therefore sole separatel% and !se sol!tion post fa+to to

    get ,

    For +o"pressi*le flo$ 9 soled fro" +ontin!it% e!ation

    fro" energ% e!ation and p - '9( fro" e!ation of

    state 'eg ideal gas la$(, For in+o"pressi*le flo$ 9 -

    +onstant and !n+o!pled fro" +ontin!it% and "o"ent!"

    e!ations the latter of $hi+h +ontains $ s!+h that

    referen+e p is ar*itrar% and spe+ified post fa+to 'i,e, for

    in+o"pressi*le flo$ there is no +onne+tion *et$een p and

    9(, he +onne+tion is *et$een$

    and0V

    = i,e, asol!tion for p re!ires 0V = ,

    )S 21 D

    #V$ V

    #t

    = + D$ $ '= +

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    Professor Fred Stern Fall 2006 52

    ('1S 'See deriation details on p,81(

    2 21 ,i

    , i

    uu#V $#t ( (

    = +

    For 0V = :

    i

    ,

    ,

    i

    (

    u

    (

    u$

    = 2

    Poisson e!ation deter"ines press!re !p to additie

    +onstant,

    Appro/i"ate odels:

    1( Sto@es Flo$

    For lo$ Re 1 ] 0)*

    V V

    =

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    0V =21V

    $ Vt

    = +

    0(' 2 = $1S

    2( .o!ndar% Ma%er !ations

    For high Re 1 and atta+hed *o!ndar% la%ers or

    f!ll% deeloped free shear flo$s '$a@es ets "i/ing

    la%ers( v )

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    Professor Fred Stern Fall 2006 54

    3( Inis+id Flo$

    ( ) 0

    b

    ' ( '

    Vt#V

    & $ 4uler 4Iuation nonlinear %y$erboli#t

    #% #$- J $ V J un-no!ns and % - f $

    #t #t

    + =

    =

    = + =

    4( Inis+id In+o"pressi*le Irrotational

    2

    0

    0 0 b b

    V V

    V linear elli$tic

    = =

    = =

    !ler !ation .erno!lli !ation:

    2

    2$ V &' const

    + + =

    an% elegant sol!tions: Mapla+e e!ation !sing

    s!perposition ele"entar% sol!tions separation of

    aria*les +o"ple/ aria*les for 2# and .o!ndar%

    le"ent "ethods,

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    Co!ette Shear Flo$s: 1# shear flo$ *et$een s!rfa+es of

    li@e geo"etr% 'parallel plates or rotating +%linders(,

    Stead% Flo$ .et$een Parallel Plates: Combined Couette

    and 3oiseuille lo!7

    0

    0

    0

    ( y '

    (

    V

    u v !

    u

    =+ + =

    =2D

    #V$ V

    #t = + 0=+++

    'y( !uvuuu

    t

    u

    D0 ( yy$ u= ++= J-

    #t

    #Jc

    $

    2 0( y '

    JuJ vJ !J

    t

    + + + =

    2

    0yyy

    u-J +=

    (note inertia terms vanis% in%erently and 5 is absent

    from eIuations)

    2 2 2

    2 2

    2

    2 2 2

    ' ( ' ( ' (

    ' (

    ( y '

    ( y y ' ' (

    ( y '

    y

    u v !

    v u ! v u !

    u v !

    u

    = + +

    + + + + + +

    + + +

    =

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    1on-dimensionali'e eIuations, but dro$ N

    )uu

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    Professor Fred Stern Fall 2006 5=

    Sol!tion depends on2

    D(

    %B $

    )= :

    . 0 D($ is opposite to

    . 0,5 *a+@flo$ o++!rs near lo$er $all

    c.c 1 flo$ approa+hes para*oli+ profilePress!re gradient effe+t

    22 3 4Pr Pr Pr 1 '1 ( '1 ( ' ( '1 (

    2 8 6 12

    c c c4 4 B 4 BJ y y y y y= + + +

    G55555555555555555555555H

    1ote usually 3r4cis Iuite small

    Substance 3r4 c dissi$ation

    Air 0,001 er% s"all

    >ater 0,02d

    Pr

    Brin-man

    4Brc

    =

    =

    Cr!de oil 20 large

    P!re

    +ond!+tion

    rises d!e to

    is+o!s dissipation

    #o"inant ter"

    for .

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    Shear Stress

    1( D 0($ = i,e, p!re Co!ette Flo$

    2 21 1

    2 2

    y

    f

    uC

    = =_

    _ 1< 2y

    u =

    %)% Re

    1==

    2

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    058:0160 Chapters 3 & 4

    Professor Fred Stern Fall 2006 5?

    _ _21 '1 (2

    u B y= __ _y

    u By= y%

    B)u

    y 2= u)=

    >here"a/2D

    (

    u%B $

    ) )= =

    #i"ensional for" ( )2 2

    "a/

    1D 1

    2

    % yu $

    %

    u

    =

    14 2 43 "a/34

    %udyu"%

    %

    ==

    "a/

    3

    2

    2u

    %

    "u ==

    %u

    %

    u

    %

    B)

    lo!er%

    B)

    u$$er%

    B)u

    !

    %yy!

    32

    "a/

    ===

    +=

    ===

    6Re6

    2

    1 02 ==== %f!

    f C3or%u

    )

    C

    /+ept for n!"eri+al +onstants sa"e as for +ir+!lar pipe,

    2

    ,

    ,

    u lam

    u turb

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    Rate of heat transfer at the $alls:

    %

    )JJ

    %

    -J-I

    %yy!

    4

    ('

    2

    2

    01 ==

    B - !pper - lo$er

    Eeat transfer +oeffi+ient:

    ( )1 0!I

    J J=

    212

    Br-

    %1u ==

    For .r 2 *oth !pper & lo$er $alls "!st *e +ooled to

    "aintain 1and 0

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    058:0160 Chapters 3 & 4

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    Conseration of Ang!lar o"ent!": "o"ent for" of

    "o"ent!" e!ation 'not ne$ +onseration la$V(

    0

    sys

    B O r V dm= = = an&ular momentum of system aboutinertial coordinate system 97

    r V=

    ( ) ( )

    0

    CV CS

    d O d

    r V d r V V n dAdt dt = + == 0M vector sum all eternal moments a$$lied CV

    due to bot% B and S7

    For !nifor" flo$ a+ross dis+rete inlet

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    a@e inertial fra"e 0 as fi/ed to earth s!+h that CS

    "oing at Vs- R i

    2 0D DV V i R i= 2 Dr R,=

    1 0

    DV V -= 1 D0r ,=

    0$i$e

    "V

    A=

    2 12 10 inD ' ( ' (P outM J - r V m r V m= = & &

    out inm m "= =& &

    0D D' (' (oJ - R V R - " =

    0 0

    2

    V J

    R "R

    = interestin&ly, even for J99, /maV9;R

    Retarding tor!e d!e to*earing fri+tion

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    #ifferential !ation of Conseration of Ang!lar

    o"ent!":

    Appl% C for" for fi/ed C:

    '&- ang!lar a++elerationQ - "o"ent of inertia

    2 2 2 2'

    d( d( dy dyQ a dy b dy c d( d d( = + &

    ( )' y yQ ddy = &

    Sin+e3 3 2 2

    12 12Q d(dy dyd( d(dy d( dy

    = + = +

    2 2

    12 ' (y y(d( dy

    + =

    &

    0 0li"

    d( dy y((y = si"ilarl% '((' = 'yy' =

    i,e ,ii, = stress tensor is symmetric (stressest%emselves cause no rotation)

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    .o!ndar% Conditions for is+o!sFlo$ Pro*le"

    he # to *e dis+!ssed ne/t +onstit!te an I.P for

    a s%ste" of 2ndorder nonlinear P# $hi+h re!ire

    .C for their sol!tion depending on ph%si+al pro*le"

    and appropriate appro/i"ations,

    %pes of .o!ndaries:

    1, Solid S!rfa+e2, Interfa+e

    3, Inlet

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    1, Solid S!rfa+e

    a, Mi!id

    - "ean free path fl!id "otion therefore

    "aros+opi+ ie$ is no slip; +ondition i,e, no

    relatie "otion or te"perat!re differen+e *et$een

    li!id and solid,

    liIuid solid V V= solidliIuid JJ

    =

    /+eption is for +onta+t line for $hi+h anal%sis is

    si"ilar to that for gas,

    *, as

    S"ooth $all

    Ro!gh $all

    !

    !

    dy

    dulu =

    Spe+!lar refle+tionConseration of

    tangential "o"ent!"

    !$-0-fl!id elo+it% at$all

    #iff!se refle+tion,

    Ma+@ of refle+tedtangential "o"ent!"

    *alan+ed *% !$

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    !

    !

    dy

    du =

    al

    32

    = lo! density limit

    !

    !

    au

    2

    3=

    a)Ma = 21

    2

    !f

    C

    )

    =

    f! CMa)u =5,< =

    Eigh Re: Cf E 9799A

    Say Ma E 29

    Mo$ Re: Cf E 7HRe-:;2 Re;

    2

    1

    Re

    4,

    (

    ! Ma

    )

    u=

    Signifi+ant slip possi*le at lo$ Re high a:

    E%personi+ M Pro*le";

    Si"ilar for :

    Eigh Re: J&as J!

    Mo$ Re( )

    ,8=&as !

    f

    r !

    J JMaC

    J J

    =

    air- driing

    01,0hi+h leads to:

    Eel"holt heore" 3: )o fl!id parti+le +an hae

    rotation if it did not originall% rotate, Qr e!ialentl% in

    the a*sen+e of rotational for+es a fl!id that is initiall%

    irrotational re"ains irrotational, In general $e +an

    +on+l!de that orti+es are presered as ti"e passes, Qnl%

    thro!gh the a+tion of is+osit% +an the% de+a% ordisappear,

    Yelins Cir+!lation heore" and Eel"holt

    heore" 3 are er% i"portant in the st!d% of inis+id

    flo$, he i"portant +on+l!sion is rea+hed that a fl!id that

    he +ir+!lation of a

    "aterial loop neer

    +hanges

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    is initiall% irrotational re"ains irrotational $hi+h is the

    !stifi+ation for idealflo$ theor%,

    In a real is+o!s fl!id orti+it% is generated *%

    is+o!s for+es, is+o!s for+es are large near solid

    s!rfa+es as a res!lt of the noslip +ondition, Qn the

    s!rfa+e there is a dire+t relationship *et$een the is+o!s

    shear stress and the orti+it%,

    Consider a 1# flo$ near a $all:

    12 12

    22 22

    32 32

    2 0

    0

    u v u

    y ( y

    v

    y

    ! v

    y '

    = = + =

    = = =

    = = + =

    >hi+h sho$s that

    dy

    u(

    = 0== 'y

    Eo$eer fro" the definition orti+it% $e also see that

    he is+o!s stresses are gien *

    i, ,n $here i, i, =

    11 1 12 2 13 3

    21 1 22 2 23 3

    31 1 32 2 33 3

    (

    y

    '

    n n n

    n n n

    n n n

    + + =

    + + =

    + + =)Q: the onl% +o"ponent of

    is , A+t!all% this is a

    general res!lt in that it +an *e

    sho$n that s!rfa+eis

    perpendi+!lar to the li"iting

    strea"line,

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    Professor Fred Stern Fall 2006 =?

    ( '

    u

    y

    = =

    i,e, the $all orti+it% is dire+tl% proportional to the $all

    shear stress, his anal%sis +an *e easil% e/tended for

    general 3d flo$,

    i, , i, ,n n = at a fi/ed solid $all

    r!e sin+e at a $all $ith +oordinate /21 3

    0( (

    = =

    and

    fro" +ontin!it%2

    0v

    (

    =

    Qn+e orti+it% is generated its s!*se!ent *ehaior is

    goerned *% the orti+it% e!ation,

    )S ( ) 2here0

    V

    V

    =

    = V =

    If 0V V V = + =

    hen 2 0 = J%e 7d7e7 foris t%e *a$lace 4I7

    And V A = Since ( ) 0= A

    2 ' (

    V A

    A A

    = =

    = +

    he irrotational part of

    the elo+it% field +an *e

    e/pressed as the gradient

    of a s+alar

    Again *% e+tor identit%

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    i,e = A2

    he sol!tion of this e!ation is

    = dR

    A

    4

    1

    h!s 31

    4

    RV d

    R

    =

    >hi+h is @no$n as the .iotSaart la$,

    he .iotSaart la$ +an *e !sed to +o"p!te the elo+it%

    field ind!+ed *% a @no$n orti+it% field, It has "an%

    !sef!l appli+ations in+l!ding in ideal flo$ theor% 'e,g,

    $hen applied to line orti+es and orte/ sheets it for"s

    the *asis of +o"p!ting the elo+it% field in orte/latti+eand orte/sheet liftings!rfa+e "ethods(,

    he i"portant +on+l!sion fro" the Eel"holt

    de+o"position is that an% in+o"pressi*le flo$ +an *e

    tho!ght of as the e+tor s!" of rotational and irrotational

    +o"ponents, h!s a sol!tion for irrotational part V

    represents at least part of an e/a+t sol!tion, nder +ertain+onditions high Re flo$ a*o!t slender *odies $ith

    atta+hed thin *o!ndar% la%er and $a@e Vis s"all oer

    "!+h of the flo$ field s!+h that V is a good

    appro/i"ation to v , his is pro*a*l% the strongest

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    !stifi+ation for idealflo$ theor%, 'incom$ressible,

    inviscid, and irrotational flo!),

    )oninertial Referen+e Fra"e

    h!s far $e hae ass!"ed !se of an inertial referen+e

    fra"e 'i,e, fi/ed $ith respe+t to the distant stars in

    deriing the C and differential for" of the "o"ent!"

    e!ation(, Eo$eer in "an% +ases noninertial referen+efra"es are !sef!l 'e,g, rotational "a+hiner% ehi+le

    d%na"i+s geoph%si+al appli+ations et+(,

    i rel

    dVa a

    dt= +

    i rel

    dV+ ma m adt

    = = +

    rel

    dV+ ma m

    dt = 1 2 3

    rRSi +=

    i,e )e$ton`s la$

    applies to non

    inertial fra"e $ith

    addition of @no$n

    inertial for+e ter"s

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    058:0160 Chapters 3 & 4

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    i

    d RV V r

    dt= + +

    2

    22 ' (i

    rel

    dV d R d a r V r

    dt dt dt

    dVa

    dt

    = + + + +

    = +

    2

    2

    dt

    Rd acceleration (,y,')

    rdt

    d - an&ular acceleration (,y,')

    2 V - Coriolis acceleration

    (' r - centri$etal acceleration (-W2*, !%ere * normal

    distance from r to ais of rotation W)7

    Sin+e R and W ass!"ed @no$n altho!gh "ore

    +o"pli+ated $e are si"pl% adding @no$n

    inho"ogeneities to the "o"ent!" e!ation,

    C for" of o"ent!" e!ation for noninertial

    +oordinates:

    rel R

    CV CV CS

    d+ a d V d v V n dAdt

    = +

    #ifferential for" of o"ent!" e!ation for noninertial

    +oordinates:

    rdterm from fact t%at

    (,y,') rotatin& at W(t)7

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    Professor Fred Stern Fall 2006 8=

    2D 23

    rel ,i i,

    ,

    #Va & $ V

    #t

    + = +

    ( ) vrrRa rel +++=

    2

    All ter"s in rela seldo" a+t in !nison 'e,g, geoph%si+al

    flo$s(:

    R ] 0 earth not a++elerating relatie to distant stars

    ] 0 for earth

    ( )r ] 0 g nearl% +onstant $ith latit!de

    v2 "ost i"portantV

    1

    0 '2 (idVa R Vdt

    = + 00

    tVVV tV *

    = =

    2

    0 00

    0

    V * V

    R RossbyV *

    = = =

    if M is large i,e, +o"para*le to the

    order of "agnit!de of the earth

    radi!s R01 then Coriolis ter" is

    larger than the inertia ter"s and is

    i"portant,

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    /a"ple of )oninertial Coordinates:

    eoph%si+al fl!ids d%na"i+s

    At"osphere and o+eans are nat!rall% st!died !sing non

    inertial +oordinate s%ste" rotating $ith the earth, $o

    pri"ar% for+es are Coriolis for+e and *!o%an+% for+e d!e

    to densit% stratifi+ation 9 - 9'(, .oth are st!died !sing

    .o!ssines appro/i"ations '9 - +onstant e/+ept

    ( ) DJ &- ter" and O @ Cp- +onstant( and thin la%er on

    rotating s!rfa+e ass!"ption *O)? ] ,

    #ifferen+es *et$een at"ospheri+al o+eans: lateral

    *o!ndaries '+ontinents( in o+eans +!rrents in o+ean 'g!lf

    and Y!roshio strea"( along $estern *o!ndaries +lo!ds

    and latent heat release in at"osphere d!e to "oist!re

    +ondensation o+ean- 0,1]1 or 2 "

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    Coriolis for+e - 2 V

    -!vu

    -,i

    'y(

    GGG

    - ( )

    + +ossinsin+os2

    GGG

    u-u,v!i

    -GGG

    +os2 -u,fuifv + sin2=f

    f 0 northern he"isphere

    f 0 so!thern he"isphere

    f - at poles

    0 sin+e $

    - planetar%orti+it%

    - 2 _ erti+al

    +o"ponent WPerson

    spins at

    W

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    f - 0 at e!ator

    !ations of otion

    0V =

    !

    &

    '

    $

    #t

    #!

    vy

    $fu

    #t

    #v

    u(

    $fv

    #t

    #u

    2

    00

    2

    0

    2

    0

    1

    1

    1

    +

    =

    +=+

    +

    =

    ('100

    JJ= p 9 - pert!r*ation fro" h%drostati+

    +ondition

    eostrophi+ Flo$: !asistead% larges+ale "otions in

    at"osphere or o+ean far fro" *o!ndaries

    (

    $fv

    =

    0

    1

    y

    $fu

    =0

    1

    2

    ] 0#V )

    #t *

    ] 0 ' (f V f) M - horiontal s+ales

    Ross*% n!"*er - f*)

    At"osphere: ] 10 "

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    herefore negle+t#V

    #tand sin+e there are no *o!ndaries

    negle+t2V ,

    "o"ent!" $

    &'

    =

    *aro+lini+ 'i,e, p - p'((

    and +an *e !sed to eli"inate p in a*oe e!ations

    $here*% '!( - f''(( $hi+h is +alled ther"al $ind *!t

    not +onsidered here,

    If $e negle+t 9-9'( effe+ts '!( - f'p( and +an *e

    deter"ined fro" "eas!red p'/%(, )ot alid near thee!ator 'B 3o( $here f is s"all,

    ( )0

    1D D D D D D$ $ $ $u i v , $ i , i ,f y ( ( y

    + = + +

    - 0

    i,e Vis perpendi+!lar to $ horiontal elo+it% is

    along 'and not a+ross( lines of +onstant horiontal

    press!re $hi+h is reason iso*ars and strea" lines

    +oin+ide on a $eather "apV

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    @"an Ma%er on Free S!rfa+e: effe+ts of fri+tion near

    *o!ndaries

    is+o!s la%ers:

    S!dden a++eleration flat plate: t yyu u=

    3,64 t =

    Qs+illating flat plate: yyt uu =

    6,5

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    ='

    u at - 0

    0='

    v at - 0

    0(' =vu at -

    !ltipl% e!ation *% 1=i and add to !e!ation:

    2

    2

    d V i f V

    dt

    = V u i v

    com$le( velocity

    = +

    ='1 ( < '1 (

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    F, )ansen '1?02( o*sered drifting ar+ti+ i+e drifted 20

    400to the right of the $ind $hi+h he attri*!ted to

    Coriolis a++eleration, Eis st!dent @"an '1?05( deried

    the sol!tion,

    Re+all f 0 in so!thern he"isphere so the drift is to the

    left of \,

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    Si"ilar sol!tion for i"p!lsie $ind:

    0(0'00 ====== 'u'u'uuu'''t

    tu

    20=

    la"inar sol!tion0

    0' 6 < 20 (

    !indu V m s J C = = = 97H m;s after one min7, 27 m;s

    after one %our

    t!r*!lent sol!tion(more realistic)u9972 m;s after : %r ( Y v!ind)

    For @"an la%er si"ilar +onditions m - 400)

    Ma"inar sol!tion !0- 2,= "