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#1 2014-04-01 03:48:31

Cindy
Member
Registered: 2011-04-12
Posts: 35

How to assign the thermal conductivity?

The thermal conductivity is space-dependent. That is k=f(x,y,z). How to specify it in Code_Aster? Thank you.

C.

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#2 2014-04-01 07:27:05

gouater
Member
From: LYON
Registered: 2007-11-26
Posts: 677

Re: How to assign the thermal conductivity?

si c'est un matériau orthotrope, alors t'as une valeur de K constante mais pour chacune des direction, voir THER_ORTH.
sinon, k peut être une fonction de du temps (INST), je ne sais pas si c'est possible que ce soit une fonction de l'espace ..


Toutes les choses deviennent difficiles, dès lors qu'on s'y intéresse un petit moment
neutral + hmm = smile

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#3 2014-04-01 15:06:21

Cindy
Member
Registered: 2011-04-12
Posts: 35

Re: How to assign the thermal conductivity?

The thermal conductivity is not orthotropic. Instead it is isotropic at each point in space but varies spatially. How to assign it to the material in the model? Is it possible to use a function of time (INST) for a space? Thank you.

C.

gouater wrote:

si c'est un matériau orthotrope, alors t'as une valeur de K constante mais pour chacune des direction, voir THER_ORTH.
sinon, k peut être une fonction de du temps (INST), je ne sais pas si c'est possible que ce soit une fonction de l'espace ..

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#4 2014-04-25 21:29:43

Cindy
Member
Registered: 2011-04-12
Posts: 35

Re: How to assign the thermal conductivity?

Sigh...... There are 122 views but no one can answer the question...... Any help is greatly appreciated.

C.

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#5 2014-04-26 07:48:51

mathieu.courtois
Administrator
From: France
Registered: 2007-11-21
Posts: 1,170

Re: How to assign the thermal conductivity?

Hello,

I think you must define the conductivity as a function of a "dependency variable" (a.k.a. "variable de commande").

Example: ssnp160a

LAMBDA = FORMULE(NOM_PARA=('NEUT1',),VALE='NEUT1')
ACIERTH=DEFI_MATERIAU(THER_FO=_F(LAMBDA=LAMBDA, RHO_CP=RHOCP));

=> lambda = f(NEUT1) (=NEUT1)

and then, define the field of NEUT1:

NEUTG=CREA_CHAMP( ...)

CMTH=AFFE_MATERIAU(MAILLAGE=MA,
                  AFFE=_F(GROUP_MA='CUBE_G',MATER=ACIERTH,),
                     AFFE_VARC=(_F(GROUP_MA='CUBE_G',
                                  CHAM_GD=NEUTG,
                                  NOM_VARC='NEUT1'),),
                  )

You can set the field by evaluating a formula on the geometry coordinates (see CREA_CHAMP/EVAL examples).

According to changelog 11.2.13, I think the usage of dependency variables is very limited in thermics (THER_LINEAIRE and not THER_NON_LINE) while it's widely available in mechanics.

Hope this helps.

MC


Code_Aster release : last unstable on Ubuntu 16.04 64 bits - GNU Compilers

Please do not forget to tag your first post as *SOLVED* when it is!

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#6 2014-09-04 20:01:28

Ivp
Member
Registered: 2011-06-03
Posts: 110

Re: How to assign the thermal conductivity?

Hi to everyone,

I want to continue this discussion and I would like to know if it's possible using the variable NEUT in order to assign boundary conditions.
Something like this:

Flux = FORMULE(VALE='NEUT1', NOM_PARA='NEUT1',);

CC_enf=AFFE_CHAR_THER_F(MODELE=Mod_Term,
                        FLUX_REP=_F(GROUP_MA=('Inf','Sup','Lat',),
                                   FLUN=Flux,),);

...

Ch_Flux=CREA_CHAMP(TYPE_CHAM='NOEU_NEUT_R',
		        OPERATION='EVAL',
			#PROL_ZERO='OUI',
		        CHAM_F=Ch_FluxN,
		        CHAM_PARA=Anterior,
			INFO=1,);

Aso_Term=AFFE_MATERIAU(MAILLAGE=Malla,
                       MODELE=Mod_Term,
                       AFFE=_F(TOUT='OUI',MATER=Ac,),
                       AFFE_VARC=
				_F(GROUP_MA=('Inf','Sup','Lat',), NOM_VARC='NEUT1', CHAMP_GD=Ch_Flux,),
			);

Pterm=THER_LINEAIRE(
                       MODELE=Mod_Term,
                       CHAM_MATER=Aso_Term,
                       EXCIT=_F(CHARGE=CC_enf,),		
                       INCREMENT=_F(LIST_INST=Lis_time,
                                    INST_INIT=Inicio,
					INST_FIN=Fin,),
                       ETAT_INIT=_F(VALE=T_aust,),
                       PARM_THETA=1.0,);

I try to do it but an error appears. I use Code-Aster v11.3.
I look forward to knowing your opinions about my question.

Best regards

Last edited by Ivp (2014-09-04 20:01:58)

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#7 2021-05-04 17:55:04

Pisolino
Member
From: Italy
Registered: 2009-04-06
Posts: 60

Re: How to assign the thermal conductivity?

mathieu.courtois wrote:

Hello,

I think you must define the conductivity as a function of a "dependency variable" (a.k.a. "variable de commande").

Example: ssnp160a

LAMBDA = FORMULE(NOM_PARA=('NEUT1',),VALE='NEUT1')
ACIERTH=DEFI_MATERIAU(THER_FO=_F(LAMBDA=LAMBDA, RHO_CP=RHOCP));

=> lambda = f(NEUT1) (=NEUT1)

and then, define the field of NEUT1:

NEUTG=CREA_CHAMP( ...)

CMTH=AFFE_MATERIAU(MAILLAGE=MA,
                  AFFE=_F(GROUP_MA='CUBE_G',MATER=ACIERTH,),
                     AFFE_VARC=(_F(GROUP_MA='CUBE_G',
                                  CHAM_GD=NEUTG,
                                  NOM_VARC='NEUT1'),),
                  )

You can set the field by evaluating a formula on the geometry coordinates (see CREA_CHAMP/EVAL examples).

According to changelog 11.2.13, I think the usage of dependency variables is very limited in thermics (THER_LINEAIRE and not THER_NON_LINE) while it's widely available in mechanics.

Hope this helps.

MC


Hi Mathieu,
can you confirm that also in v15 the ther_non_line solver can't use NEUT variables ?  I'm struggling with this problem in order to understand what is feasibile and what is not.
Thank you in advance.

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