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A new approach for three-phase flows

Jean-Marc Hérard

To cite this version:

Jean-Marc Hérard. A new approach for three-phase flows. 4th AIAA Theoretical Fluid Me- chanics Meeting, American Institute Aeronautics and Astronautics, Jun 2005, Toronto, Canada.

�10.2514/6.2005-4939�. �hal-01582727�

(2)

Jean-Mar Herard

EDF-DRD,78401Chatou edex,Frane

Wepresenthereanewmodeltodesribe three-eldpatternsor three-phaseows. The

basi ideas rely on the ounterpart of the two-uid two-pressure model whih has been

introdued in the DDT framework, and more reently extended to water-vapour simula-

tions. We show the systemis hyperboli without any onstraining ondition on the ow

patterns. A detailed investigation of the struture of the Riemann problem is ahieved.

Regular solutions ofthe whole arein agreementwith physial requirements onvoid fra-

tions, densities and internal energies for a rather wide lass of equations of state. Even

more, this approah enables to perform omputations of standard single pressure three-

phase owmodels, using relaxation tehniques and oarse meshes. A few omputational

results onrmthe stability ofthe wholeapproah.

I. Introdution

Some simulations in the framework of pressurized powerreators in the nulear energy require using

two-uidmodels,andsomeothersevenaskforathreeelddesriptionofthewholeow(see 1,2

). Thismay

happenforinstane whenpreditingthemotionofliquiddispersed dropletsinsideaontinuousgasphase,

whilesomegas-liquidinterfaeismovingintheore. Otherappliationsinvolvingagaseousphaseandtwo

distintliquids(forinstane oilandwater)also urgeforthedevelopmentofthreeeld models.

Somemodelsandtoolshavealreadybeenproposed,whihbasiallyrelyonthetwo-uidsingle-pressure

formalism. These either assume that liquiddropletsveloities andveloitiesin thesurrounding gasphase

areequal,orretaindierentveloitiesbutassumeinanyasealoalpressureequilibriumbetweenthethree

omponents. A straightforward onsequene is that these models suer from the same deienies than

standardtwo-uidmodels. Morelearly,thelossofhyperboliityoftheonvetivesubsetimpliesthatom-

putationsonsuÆientlyne gridsrathereasilyenter "elliptiin time"regions;asaonsequene,eventhe

most"stable"upwindingshemesleadtoablowupoftheodewhenreningthemesh,thoughaounting

forstabilizingdrag eets(see 3

forinstane forsuhanumerialexperiene).

An alternativewayto dealwith these ows onsists in gettingrid of thepressureequilibrium between

phases. Thiswas rstintrodued intheframeworkoftheDDT (see, 4{15

among others),andmorereently

appliedtowater-vapourpreditions(see 16{18

). Oneofthemainadvantageswiththelatterapproahisthat

itinherits from the hyperbolistruture of Navier-Stokesequations-whihseems quitereasonable-onthe

onehand;moreover,theoverallentropyinequalityprovidessomebetterunderstandingofvariousinterfaial

transfer terms. For all these reasons, it seems appealing to examine whether one might derive a similar

framework to opewith three-phase orthree-eld ow strutures. Suh atrialis disussed in this paper.

An underlying idea is that the interfae between phases remains innitely thin when submitted to pure

onvetivepatterns.

ResearhEngineer,DepartementMFTT,6quaiWatier,andAssoiateResearhDiretor,CNRS,LATP,AIAAMember

(3)

eets. Themain properties of thewhole set will be examined, inludinga disussion onthe solutionsof

the one dimensional Riemann problem. These properties enable to ompute the whole set with help of

roughshemes(Rusanovsheme)ormoreaurateapproximateRiemannsolverssuhastheoneintrodued

in.

19,20

A few omputationalresultsillustrate thewhole,whih issuefrom theomputation of aRiemann

problem.

II. Governing equations

Thedensity,veloity, pressure,internalenergy andtotalenergywithin phasek willbedenoted

k ,U

k ,

P

k ,e

k

=e

k (P

k

;

k

)andE

k

=0:5

k U

k U

k +

k e

k

respetively. Thevolumetrifrationofphaselabelledkis

denedas

k

,andthethreemustomplywiththeonstraint:

1

=1

2

3

Thegoverningset ofequationsis:

(I+D(W)) W

t +

F(W)

x

+C(W) G(W)

x

=S(W)+

x (E(W)

W

x

) (1)

It requires aninitial onditionW(x;0)=W

0

(x) andsuitable boundary onditions. Thestatevariable W,

theuxesF(W),G(W)andthesouretermsS(W)lieinR 11

. Weset:

W t

=(

2

;

3

;

1

1

;

2

2

;

3

3

;

1

1 U

1

;

2

2 U

2

;

3

3 U

3

;

1 E

1

;

2 E

2

;

3 E

3 )

and,notingm

k

=

k

k :

F(W) t

=(0;0;m

1 U

1

;m

2 U

2

;m

3 U

3

;

1 (

1 U

2

1 +P

1 );

2 (

2 U

2

2 +P

2 );

3 (

3 U

2

3 +P

3 );

1 U

1 (E

1 +P

1 );

2 U

2 (E

2 +P

2 );

3 U

3 (E

3 +P

3 ))

SeondranktensorsC(W);D(W);E(W)lieinR 1 111

. Thenon-onservativeonvetivetermsare:

8

>

<

>

: D(W)

W

t

=(0;0;0;0;0;0;0;0; P

2

2

t P

3

3

t

;P

2

2

t

;P

3

3

t )

C(W) G(W)

x

=(U

1

2

x

;U

1

3

x

;0;0;0;P

2

2

x +P

3

3

x

; P

2

2

x

; P

3

3

x

;0;0;0)

(2)

Visoustermsshould atleastaountforthefollowingontributions(thermaluxesmightbeinluded):

E(W) W

x

=(0;0;0;0;0;

1

1 U

1

x

;

2

2 U

2

x

;

3

3 U

3

x

;

1

1 U

1 U

1

x

;

2

2 U

2 U

2

x

;

3

3 U

3 U

3

x

) (3)

Soure termsS(W)aountformasstransferterms,drag eets, energyloss,andother ontributions. To

simplify ourpresentation,weonlyretain heretheeetofpressurerelaxationanddrageets. Thus:

S(W)=(

2

;

3

;0;0;0;S

U1

;S

U2

;S

U3

;U

1 S

U1

;U

1 S

U2

;U

1 S

U3

) (4)

Wealsoset

1

=

2

3

andwereallthatthemomentuminterfaialtransfertermsmustomplywith:

S

U1

(W)+S

U2

(W)+S

U3

(W)=0

(4)

Wefousrstonthehomogeneousproblemassoiatedwiththelefthandsideof (1). Wedeneasusual

speientropiess

k

andspeeds

k

intermsofthedensity

k

andtheinternalenergye

k :

(

k )

2

= kPk

k

=( P

k

(

k )

2 e

k (P

k

;

k )

k )(

e

k (P

k

;

k )

P

k )

1

k P

k s

k (P

k

;

k )

P

k

+

k s

k (P

k

;

k )

k

=0

Property1 :

1:1Thehomogeneoussystemassoiatedwiththelefthandsideof (1)haseigenvalues:

1;2;3

=U

1 ,

4

=U

2 ,

5

=U

3 ,

6

=U

1

1 ,

7

=U

1 +

1 ,

8

=U

2

2 ,

9

=U

2 +

2 ,

10

=U

3

3 ,

11

=

U

3 +

3

. Assoiatedrighteigenvetorsspan thewhole spaeR 11

unlessU

1

=U

k +

k orU

1

=U

k

k , for

k=2;3.

1:2Fieldsassoiatedwitheigenvalues

k

withkin(1;2;3;4;5)areLinearlyDegenerate;othereldsare

Genuinely NonLinear.

Thelist ofRiemann invariantsthroughLDelds assoiatedwith k=4;5andGNL eldsmaybeom-

putedquiteeasilyusingvariable: Z t

=(

2

;

3

;s

1

;s

2

;s

3

;U

1

;U

2

;U

3

;P

1

;P

2

;P

3

)(seeappendiesA,B,Cin 21

).

Property2 :

2:1ThelattersystemadmitsthefollowingRiemanninvariantsthroughthe1 2 3LDwave:

I 1 2 3

1

(W)=m

2 (U

2 U

1

) I

1 2 3

2

(W)=m

3 (U

3 U

1 )

I 1 2 3

3

(W)=s

2 I

1 2 3

4

(W)=s

3 I

1 2 3

5

(W)=U

1

I 1 2 3

6

(W)=

1 P

1 +

2 P

2 +

3 P

3 +m

2 (U

1 U

2 )

2

+m

3 (U

1 U

3 )

2

I 1 2 3

7

(W)=2e

2 +2

P2

2 +(U

1 U

2 )

2

I 1 2 3

8

(W)=2e

3 +2

P3

3 +(U

1 U

3 )

2

2:2Wenote ( )=

r l

. Apartfrom the1 2 3LDwave,thefollowingexatjump onditionshold

fork=1;2;3,throughanydisontinuityseparatingstatesl;rmovingwithspeed:

(

k )=0

(m

k (U

k

))=0

(m

k U

k (U

k

)+

k P

k )=0

(

k E

k (U

k

)+

k P

k U

k )=0

Weneedtodene:

a

k

=(s

k )

1

( s

k (P

k

;

k )

P

k )(

e

k (P

k

;

k )

P

k )

1

(5)

and:

k

=Log(s

k

),butalsothepair(;F

)suhthat : = m

1

1 m

2

2 m

3

3

,and: F

= m

1

1 U

1

m

2

2 U

2 m

3

3 U

3

. DragtermsS

U

k

(W)andsoureterms

k

(W)in(1)omplywith:

0a

2 (U

1 U

2 )S

U

2

(W)+a

3 (U

1 U

3 )S

U

3

(W) (6)

0a

1 (

1 P

1 +

2 P

2 +

3 P

3

) (7)

Condition(7)reads:

2 (P

1 P

2 )+

3 (P

1 P

3 )0

(5)

1 2 3 1

Property3 :

Closures in agreement with the above mentionned onstraints (6),(7) ensure that the following entropy

inequalityholdsforregularsolutionsof (1):

t +

F

x

0 (8)

Wefromnowwillassumethattheonditions(6),(7)arefullled. Foronvenienywewillhoosehere:

2

=f

1 2 (W)

1

2 (P

2 P

1 )=(P

1 +P

2 +P

3

) (9)

3

=f

1 3 (W)

1

3 (P

3 P

1 )=(P

1 +P

2 +P

3

) (10)

wherepositivesalarfuntionsf

k l

(W)denoteboundedfrequenies. Itiseasytohekthat:

1 P

1 +

2 P

2 +

3 P

3

>0

Evenmore,thegoverningequation of =

1

2

3

guaranteesthat regularsolutions

k

(x;t)remainin the

admissiblerange[0;1℄. Wewill relyonstandardlosuresoftheform(see 2

forinstane):

S

U2 (W)=

2 (W)(U

1 U

2

) (11)

S

U

3 (W)=

3 (W)(U

1 U

3

) (12)

wherethesalarfuntions

2 (W),

3

(W)should remainpositive. Hene(6)and(7)hold.

Property4 :

We assume perfet gas state law within eah phase (k = 1;2;3). We onsider a single wave assoiated

with

m

,separatingstatesl;r. Ifthe initialonditionssatisfy: (

k )

L;R

(1

k )

L;R

6=0,fork =1;2;3the

onnetionofstatesthroughthiswaveensuresthatallstatesareinagreementwith: 0

k ,0m

k ,0P

k .

Atually,theproofisalmostobviouswhenfousingonasingleeldonnetedwitheigenvalue

k where

k=4to11. Turningthentothe1;2;3-eld,themainguidelines(seeappendixEin 21

)arethesameasin.

17

Detailsonsomesuitableforms ofmassandenergytransfertermsanbefoundinappendixFin.

21

IV. Numerial approah

Thewholeenablestointrodueafrationalstepapproahinagreementwiththeoverallentropyinequality,

whih isagain the ounterpart ofthe onedesribed in.

17

Wethus simply omputeapproximationsof the

onvetivesubset:

(I+D(W)) W

t +

F(W)

x

+C(W) G(W)

x

=0 (13)

andthenaountforsouretermsandvisoustermsupdatingvaluesthroughthestep:

(I+D(W)) W

t

=S(W)+

x (E(W)

W

x

) (14)

This frational step method is in agreement with the whole entropy inequality. When negleting visous

ontributions,theseondoneturnstoanordinarydierentialsystem.

Our basiapproahto ompute onvetivetermsrelies on theGodunov approah.

22,23

More preisely

here,weusethe shemesintrodued in 17

to omputeapproximationsof thesystem(13). This is ahieved

(6)

withhelpofeithertheRusanovshemeortheapproximateGodunovshemeVFRoe-nv. Inordertoope

with thestandardstep (13)whih requiresdisretizing onvetiveeets, arather eÆientwayonsists in

usingtheapproximateGodunovshemeintrodued in 19

withthespeivariable:

Z t

=(

2

;

3

;s

1

;s

2

;s

3

;U

1

;U

2

;U

3

;P

1

;P

2

;P

3

) (15)

(see 20

whih details themain advantages of suh ahoie). Computations belowhavebeenobtainedwith

theformersheme,whilefulllingstandardCFLonditions.

One mustbearefulwhen providing approximationsofsystem(14). Otherwise,thestabilityof loally

equal-pressureregionsmaybeviolated. Theonnetionwiththeshemeintroduedin 24

isobvious.

Thisapproahhasanotheradvantage,sineitalsoenablestoopewiththeinstantaneouspressureequi-

libriumassumption. Thisisusefultoomputemodelssuhasthosedesribedin 2

forinstane. Owingtothe

entropystruture(seeappendixDin 21

),onemayatuallyintroduethepressurerelaxationstepinvolvedin

(14)asatooltoomputethesinglepressuremodelsdetailedin.

2

Thisistheounterpartofwhathasbeen

ahievedin thetwo-phaseframework(see 25,26

or 3

forinstane).

V. A few omputations of the shok tube apparatus

We restrit here to some simple omputations of the shok tube apparatus. We use a uniform mesh

with 10000ellsand set CFL=0:49 in order to avoidthe interation of waveswithin the ells. In these

omputations,allsouretermsandvisoustermshavebeennegleted,inordertoassessthestabilityofthe

wholeonvetivesubset.

We assume that the perfet gas law holds within eah phase:

k e

k

= (

k 1)P

k

, setting

1

= 7=5,

2

= 1:05 and

3

= 1:01. Initial onditions are : (

2 )

L

= 0:4, (

3 )

L

= 0:5, (

2 )

R

= 0:5, (

3 )

R

= 0:4,

(U

1 )

L

= 100, (

1 )

L

= 1, (P

1 )

L

= 10 5

, (U

1 )

R

= 100, (

1 )

R

= 8, (P

1 )

R

= 10 5

, (U

2 )

L

= 100, (

2 )

L

= 1,

(P

2 )

L

=10 5

, (U

2 )

R

=100, (

2 )

R

= 8, (P

2 )

R

=10 5

, (U

3 )

L

= 100,(

3 )

L

=1, (P

3 )

L

=10 5

, (U

3 )

R

=100,

(

3 )

R

= 8, (P

3 )

R

= 10 5

, for the rst ase (g. (1-3)), and: (

2 )

L

= 0:4, (

3 )

L

= 0:5, (

2 )

R

= 0:5,

(

3 )

R

=0:4, (U

1 )

L

=0,(

1 )

L

=1,(P

1 )

L

=10 5

, (U

1 )

R

=0,(

1 )

R

=8,(P

1 )

R

=10 4

, (U

2 )

L

=0,(

2 )

L

=1,

(P

2 )

L

=10 5

,(U

2 )

R

=0,(

2 )

R

=8,(P

2 )

R

=10 4

,(U

3 )

L

=0,(

3 )

L

=1,(P

3 )

L

=10 5

, (U

3 )

R

=0,(

3 )

R

=8,

(P

3 )

R

=10 4

,fortheseondtest.

0 2000 4000 6000 8000 10000

0.4 0.42 0.44 0.46 0.48 0.5

Void fractions alpha2 (squares), alpha3 CFL=0.49 _ 10000 cells

Figure1. Voidfrations

2 ,

3

0 2000 4000 6000 8000 10000

0 0.1 0.2 0.3 0.4 0.5

Partial masses m1 (circles), m2 (squares), m3 CFL=0.49 _ 10000 cells

Figure 2. Partial masses m1, m2,

m3

0 2000 4000 6000 8000 10000

90000 95000 1e+05 1.05e+05 1.1e+05

Pressures P1 (circles), P2 (squares), P3 CFL=0.49 _ 10000 cells

Figure3. PressuresP

1 ,P

2 ,P

3

(7)

0 2000 4000 6000 8000 10000 0

100 200 300 400

Velocities U1 (circles), U2 (squares), U3 Shock tube _ CFL=0.49 _ 10000 cells

Figure4. VeloitiesU

1 ,U

2 ,U

3

0 2000 4000 6000 8000 10000

0 0.1 0.2 0.3 0.4 0.5

Partial masses m1 (circles), m2 (squares), m3 Shock tube _ CFL=0.49 _ 10000 cells

Figure 5. Partial masses m

1 , m

2 ,

m

3

0 2000 4000 6000 8000 10000

0 20000 40000 60000 80000 1e+05

Pressures P1 (circles), P2 (squares), P3 Shock tube _ CFL=0.49 _ 10000 cells

Figure6. PressuresP

1 ,P

2 ,P

3

VI. Conlusion

Thisnewmodelbenetsfromimportantproperties. Fromaphysialpointofview,aninterestingpointis

thatitpreservesthepositivityof(expeted)positivequantities: voidfrations,massfrationsandinternal

energies,atleastwhenrestritingtosuÆientlysimpleEOS.Itsmathematialpropertiesenableusto on-

strut nonlinearstable numerialmethods, and thus toexplore highly unsteadyow patterns. Conditions

toobtainaexisteneanduniquenessoftheexatsolutionoftheonedimensional Riemannproblemannot

beobtainedeasily. A spei diÆultyis linked withthe possible oureneof theresonanephenomena.

Anotherpoint,whihseemsworthbeingnoted,isthattheounterpartoftheaverage"andidate"interfae

veloityV

I

=(m

1 U

1 +m

2 U

2 )=(m

1 +m

2

)nolongerarisesin thethree-eldframework.

Another part of our urrent work onerns the omparison with standard single pressure three-eld

models, when restriting to oarse meshes. This is ahieved using relaxationtehniques, following ideas

from.

3,24{30

Aknowledgments

ThisworkhasreeivednanialsupportfromtheNEPTUNEprojet,whihhasbeenlaunhedbyEDF

(Eletriitede Frane) and CEA (Frenh Atomi Ageny), and benets from a omplementary part from

IRSNandFRAMATOME-ANP.OlivierHurisseisalsoaknowledgedforhishelp.

Referenes

1

S.JayantiandM.Valette,Preditionofdryoutandpostdry-outheattransferathighpressureusingaone-dimensional

three-eldmodel,Int.J.of HeatandMassTransfer,2004,vol.47-22,pp.4895-4910.

2

M.Valette and S.Jayanti, Annulardispersedow alulationswitha two-phasethreeeld model,European Two

phaseFlow GroupMeeting,Norway,2003,internalCEAreportDTP/SMTH/LMDS/2003-085.

3

J.M.

H

erardandO.Hurisse,Asimplemethodtoomputestandardtwo-uidmodels,submitted,2005.

4

N.Andrianov and G.Warneke, TheRiemannproblemfor the BaerNunziatotwo-phaseowmodel,J.of Comp.

Physis.,vol.195,pp434{464,2004

5

M.R.Baer and J.W.Nunziato, Atwophasemixturetheory forthe deagrationto detonationtransition(DDT)in

reativegranularmaterials,Int.J.MultiphaseFlow,1986,vol.12-6,pp.861{889.

6

F.CoquelandS.Cordier,CEMRACSenalulsientique1999,MATAPLI62,pp.27-58,2000.

7

S.Gavrilyuk,H.GouinandY.V.Perepehko,Avariationalpriniplefortwouidmodels,C.R.Aad.Si.Paris,

1997,vol.IIb-324,pp.483-490.

8

S.GavrilyukandR.Saurel,Mathematialandnumerialmodellingoftwophaseompressibleowswithmiroinertia,

J.ofComp.Phys.,2002,vol.175,pp.326-360.

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