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## #1 2020-01-14 23:20:10

mf
Member
Registered: 2019-06-18
Posts: 8

### [SOLVED] Calc total heat flux through an arbitrary surface+proposition

Good evening,

I know that similar postings concerning this topic are in this forum. Nevertheless, I did not find a satisfying answer and example to solve this problem in a reasonable time. I still consider myself a beginner in Aster. Pros may find this post useless.

So I spent nearly a day in figuring this out, using mainly topic-id=16219 (not allowed to post links).

I wanted to share part of my example, so that beginners may get to the solution quicker. It follows the answer of Mr. de Soza in above link.

Let's suppose you already have your result 'resther' from whatever thermal calculation:

resther = CALC_CHAMP(identifier='1:2',
reuse=resther,
RESULTAT=resther,
THERMIQUE=('FLUX_NOEU', 'FLUX_ELNO'))

Extract the FLUX_NOEU and name it differently:

FLU_NOEU = CREA_CHAMP(identifier='8:2',
INST=1.0,
NOM_CHAM='FLUX_NOEU',
OPERATION='EXTR',
RESULTAT=resther,
TYPE_CHAM='NOEU_FLUX_R')

Compute the normal vectors in the group_ma which is the surface of interest:

NORM_VEC = CREA_CHAMP(identifier='4:2',
GROUP_MA=('OUT_ALL', ),
MODELE=model,
OPERATION='NORMALE',
TYPE_CHAM='NOEU_GEOM_R')

Then define a formula for the normal flux:

FLUXNORM = FORMULE(identifier='25:1',
NOM_PARA=('FLUX', 'FLUY', 'FLUZ', 'X', 'Y', 'Z'),
VALE='FLUX*X+FLUY*Y+FLUZ*Z')

Create a function field with said formula:

FLU_FUNC = CREA_CHAMP(identifier='5:2',
AFFE=_F(GROUP_MA=('OUT_ALL', ),
NOM_CMP=('X1', ),
VALE_F=(FLUXNORM, )),
MODELE=model,
OPERATION='AFFE',
TYPE_CHAM='NOEU_NEUT_F')

Evaluate the function field, generating scalar values:

FLUN = CREA_CHAMP(identifier='6:2',
CHAM_F=FLU_FUNC,
CHAM_PARA=(FLU_NOEU, NORM_VEC),
OPERATION='EVAL',
TYPE_CHAM='NOEU_NEUT_R')

Integrate above scalars in group 'OUT_ALL' to get the total heat flux (I did not need 5. of Mr. de Soza's example):

FLUN_TOT = POST_ELEM(identifier='7:2',
CHAM_GD=FLUN,
INTEGRALE=_F(GROUP_MA=('OUT_ALL', ),
NOM_CMP=('X1', ),
TYPE_MAILLE='2D'),
MODELE=model,
TITRE='FLUN_TOT')

Write the table with above result:

IMPR_TABLE(identifier='11:2',
FORMAT='TABLEAU',
TABLE=FLUN_TOT,
UNITE=9)

That should be all, I assume it is correct as I verified the result with an analytical calculation. Could someone please verify this?

Last, but not least, may I address Aster developers and propose the creation of a new COMMAND doing the above calculations? It should be quite similar to CALC_PRESSION, therefore I want to propose CALC_FLUX or CALC_FLUX_THER as its name. Is this reasonable, does it make sense to the developers? I'm sure, I'm not the only one that needs such a command quite often. Would be nice and save a lot of time!

Kind regards,

Mario.

[SOLVED] because it's just for info...

Last edited by mf (2020-01-17 07:01:24)

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