constraints for the pressure-strain correlation tensor derived from spectral representation

EFMC-6, Stockholm, 2006

Constraints for the Pressure-Strain Correlation tensor derived

from Spectral Representation

S.R.Bogdanov

T.J.Jongen


Outline

• DRSM, PSC models

• The derivation of the restrictions on the “rapid” part of PSC.

• Direct checking of the models for

• Predicting the available areas of the parameters of stationary states

• Others: (Implicit) checking of the models for non-linear part of PSC, non-uniform turbulence …

)(rijФ


Differential Reynolds stress models, DRSM

Spectra of ideas, connected with the study of fully developed turbulence and calculations of the flows with the anisotropy is extremly wide: from the theory of fractals and renormalization group methods to direct numeric simulations and semiempirical modelling. At the same time nowadays the so-called first (with the turbulent viscosity as the key concept) and second-order closure (or full differential Reynolds stress models, DRSM). models are the most popular in practice.

)(2 jkmkiikmkjmij

ijxU

jkx

U

ikij k

i

k

j

)(i

j

j

i

x

u

xu

ij p

)(2k

i

k

i

xu

xu

ij


A lot of models were proposed for PSC. One of the most popular and well-known (quasi-linear) semi-empirical approximations for PSC looks like:

)()(

)(

)/(

31

54

32

3

211

01

ijnmmnkjikkjikkjik

ijnmmnkjikkjik

ijij

bbbbСbWWbKC

SbbSSbKC

KSCPСCФ

ijijijij SKbSP 2ijKij

ijb 31

2


Realizability criteria

I n s p i t e o f t h e p h y s i c a l b a c k g r o u n d a s t h e o r i g i n , t h e s e m o d e l e x p r e s s i o n ss t i l l r e m a i n r a t h e r f o r m a l a n d p o s e s s f u n c t i o n a l i n d e f i n i t n e s s . A s t h e r e s u l t t h e s o -c a l l e d r e a l i z a b i l i t y c r i t e r i a a r e o f t e n v i o l a t e d .

T h e s e c r i t e r i a , f o l l o w i n g f r o m t h e f a c t t h a t R e y n o l d s s t r e s s t e n s o r i s p o s i t i v ed e f i n i t e , a r e e x p r e s s e d a s f o l l o w s :

a n d s i m i l a r o n e s .T h e m e n t i o n e d v i o l a t i o n s a r e u s u a l l y u n p r e d i c t a b l e , a n d o n e c a n ' t a p r i o r i e v a l u a t e t h e" s u s t a i n a b i l i t y l i m i t s " o f a n y c o n c r e t e m o d e l .

2222 )(,0 uuuuu


The derivation of the restrictions on the “rapid” part of PSC.

W e s t a r t w i t h t h e e x a c t r e p r e s e n t a t i o n f o r m e a n - f l o w - i n d u c e d( " r a p i d " ) p a r t o f p r e s s u r e - s t r a i n c o r r e l a t i o n t e n s o r :

T h e d e r i v a t i o n o f t h e c o n s t r a i n t s i s b a s e d o n t h e f a c t t h a t s p e c t r a lt e n s o r $ F _ { i j } $ o f t w o - p o i n t c o r r e l a t i o n s $ R _ { i j } $ i s p o s i t i v e l y d e f i n e d :

H e r e - a r b i t r a r y c o m p l e x v e c t o r , b a rm e a n s c o m p l e x c o n j u g a t e .

0jiijF

i

kdFFUФ jmimilmjlmr

ij )(2)(


Illustration of the basic idea

F o r t h e s i m p i e s t c a s e , w h e n W = 0 :

у к е

kdSSFS jjillmmir ))((2/

llmm Sq

02/ kdqqFS immir


F o r g e n e r a l c a s e , w i t h W , i t ’ s e a s y t o d e r i v e t h e e x p r e s s i o n f o r t h e s c a l a r i n v a r i a n tq u a n t i t y :

A s m e n t i o n e d a b o v e , t h e s p e c t r a l t e n s o r i s p o s i t i v e l y d e f i n e d , s o e a c h o ft h r e e i n t e g r a l s i s a l s o p o s i t i v e . T h i s f a c t s t i l l i s n o t s u f f i c i e n t f o r d e r i v i n g t h ec o n s t r a i n t s : i t ' s a l s o n e c e s s a r y t o e v a l u a t e t h e u p p e r l i m i t s o f t h e i n t e g r a l s .

T o p u t t h i s e v a l u a t i o n f o r w a r d , w e ' l l t a k e i n t o a c c o u n t t h e f o l l o w i n gr e p r e s e n t a t i o n f o r s p e c t r a l t e n s o r :

kdWWFkdSSF

kdUUFU

iijllmmiijillmmj

jjillmmir

))(())((

))((2/

)()()()()()( 2*

1* kkbkbkkakaF jmjmmj


H e r e e i g e n v e c t o r s a a n d b ( n o r m e d t o 1 ) a r e o r t h o g o n a l t o w a v e v e c t o r k a n dc o r r e s p o n d i n g e i g e n v a l u e s a r e p o s i t i v e l y d e f i n i t e .

A n d s i m i l a r o n e s f o r q c o n s t r u c t s d w i t h W a n d U

kdkdFuK ii

)(2 21

2 2

212

2

12 )( qqbqaqqF jmmj

22 KqkdqqF jmmj

mllmSq 22 2/22 Sq


S u b s t i t u t i n g t h e d e r i v e d u p p e r l i m i t s f o r $ q ^ 2 $ i n ( 2 . 6 ) , w e o b t a i n t h e f o l l o w i n gi n e q u a l i t i e s f o r c o r r e s p o n d e n t i n t e g r a l s :

I n s u m m a r y , t h e c o n s i s t e n c y c o n s t r a i n t ( \ r e f { r e l } ) f o r t h e p r e s s u r e - s t r a i nc o r r e l a t i o n t e n s o r c a n b e e x p r e s s e d a s

T h e c o n s t r a i n t i s g e n e r a l , a p p l i c a b l e f o r a n y t y p e o f t u r b u l e n c e a n d a t a n y i n s t a n t o f t h et u r b u l e n c e e v o l u t i o n . T h e r e i s n o r e f e r e n c e y e t t o a m o d e l e x p r e s s i o n f o r t h e r a p i d p a r t o ft h e p r e s s u r e - s t r a i n c o r r e l a t i o n t e n s o r a n d s h o u l d t h e r e f o r e b e v a l i d i n a l l c a s e s .

22

2

2

)1())((0

))((0

))((0

RSKkdUUF

WKkdWWF

SKkdSSF

ijillmmj

ijillmmj

ijillmmj

)2,min(2)2,min( 2

212

2 RRURR r

SK

2

22

S

WR


Direct checking of the models for PSCW e ’ l l p r e s e n t t h e d i r e c t c h e c k i n g o f t h e P S C m o d e l s p r e s e n t e d a b o v e . S u b s t i t u t i n ge x p r e s s i o n f o r P S C i n t o b a s i c i n e q u a l i t y , a f t e r s i m p l e c a l c u l a t i o n s w e o b t a i n :

F o r f o l l o w i n g a n a l y s i s i t ’ s c o n v e n i e n t t o i n t r o d u c e t h e p a r a m e t e r s :

A n d t h e p r e v i o u s u n e q u a l i t y t a k e s t h e f o r m :

F o r a n y g i v e n t y p e o f t h e f l o w ( m a t r i x e s S a n d W ) p a r a m e t e r s B a r e e x p r e s s e d t h r o u g ht h e c o m p o n e n t s o f R e y n o l d s s t r e s s a n d R .

2242

2

322

}{

}{

}{

}{

2

1)2(2 R

S

bWSC

S

bSCCRR

}{

}{22

S

bWSB

224332

2

2

1)2(2 RBCBCCRR


We can use this constraint by two "methods". Namely- On the one hand, we can substitute in the constraint the concrete values of the set ofconstants and calculate the shape of the "sustainability area" for each concrete model.- On the other hand, we can substitute in the constraint all available values of theparameters B and derive the restrictions on the set of the model constants C.

We'll start by illustration of the second method by simple example.when themean flow is 2-D:

This lead to:

0

0

D

DU

,2121 bB )(2 22112 bbR

B 233

3

bB


W e ' l l s t a r t b y i l l u s t r a t i o n o f t h e s e c o n d m e t h o d b y s i m p l e e x a m p l e .N a m e l y i n t h e s p e c i a l c a s e w h e n R = 0 , c o n s t r a i n t s ( 3 . 3 ) a r e e x t r e m e l y s i m p l e :

H a v i n g i n v i e w t h a t p a r a m e t e r B _ 3 i s r e s t r i c t e d b y

W e o b t a i n t h e f o l l o w i n g p u r e r e s t r i c t i o n s o n t h e s e t o f c o n s t a n t s :

3

33

3

2

2

4

2 C

CB

C

C

3

1,

6

13B

3

2

34 3

23 C

CC


S i m i l a r l y , w i t h i n " f i r s t m e t h o d " , w e ' l l c o n s i d e r t h e m o r e g e n e r a l c a s e , w i t h R .W i t h r e s p e c t t o t h e p r e v i o u s r e s u l t w e ' l l t a k e i n t o c o n s i d e r a t i o n o n l y m o r e s t r o n g( r i g h t ) p a r t o f t h e b a s i x d o u b l e i n e q u a l i t y .

B u t n o w w e m u s t t a k e i n t o a c c o u n t t h e a v a i l a b l e i n t e r v a l s f o r B _ 1 a n d B _ 2 :

331

331

2 , BBRB

)/)((2 222

233

121 RBBB


It's convenient to present the available areas for the set of parameters B with graphic on B_3 - {B_2}/R plane.

Available is the inside area of the triangle ABC. 2-D turbulence corresponds to the sides of the triangle; points A,B,C correspond to 1-dimensional turbulence (with pulsations along axes 3,1,2). BE, CF, AD - present axisymmetric turbulence; At last, point O presents isotropic turbulence.

The set of hyperbola (B_1 - isolines) is also presented on the picture. When B_1 is fixed, the area of available values of the parameters B_2 и B_3/R is restricted with correspondent hyperbola and BC- line.

Y – axis: B3= -b33/2

X-axis: B2/R = (b11 – b22)/2


N o w w e ' l l a n a l y s e t h e c o n s t r a i n t s b y " f i r s t m e t h o d " , i . e . , w e ' l l s u b s t i t u t e i n t h ec o n s t r a i n t s t h e s e t o f c o n s t a n t s f o r e a c h m o d e l a n d d e r i v e t h e r a n g e s o f v a l u e s o fp a r a m e t e r s { B i } , w h i c h a r e " a v a i l a b l e " f o r e a c h m o d e l . I n t h i s w a y w e ' l l o b t a i n a l s ot h e c l e a r g e o m e t r i c a l i n t e r p r e t a t i o n o f t h e r e s u l t s d e r i v e d e a r l i e r .

I n d e e d , w e c a n p r e s e n t t h e c o n s t r a i n t

a s t h e s e t o f s t r i g h t l i n e s o n m e n t i o n e d p l a n e ( R p l a y s t h e r o l e o f t h e p a r a m e t e r ) .T h e e n v e l o p e o f t h i s s e t i s p a r a b o l a :

T h e s e t s o f m e n t i o n e d l i n e s a n d t h e i r e n v e l o p e s a r e p r e s e n t e d i n f o l l o w i n g f i g u r e sf o r d i f f e r e n t P S C m o d e l s ( S S G , L R R , T , G L ) .

224332

2

2

1)2(2 RBCBCCRR

222

24332 /)(2 RBCBCC


The available domain on invariant map


B3 - isolines


B2 - isolines, for B1=0


«Forbidden» areas on invariant map (SSG model, R=0, B1=0 and -0.1 correspondently)


A n a l y s is o f s t a t io n a r y s t a t e s , W = 0 .

W h e n C 2 = 2 …

3

3

3

312/

1 2)

22(2

C

C

C

CaCP

g

Pg

CCP

g2

332

234

/1

2

22

P

g

1

2

3/4 21

Ca

22 S

K


Stationary state analysis, SSG

0

0,5

1

1,5

2

2,5

3

3,5

0 1 2 3 4 5

P

0

0,2

0,4

0,6

0,8

1

1,2

0 1 2 3

P


Conclusion

• Possibilities of direct checking (and improving, hopefully: at least, through the proper choice of the set of the model constants) of PSC models

• Direct analysis of the parameters of stationary states.

• The link between spectral approach and one-point closures.

• Most probably turbulence is more non-local than it’s usually assumed within second-order closures.


Thank you

constraints for the pressure-strain correlation tensor derived from spectral representation

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