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Titrate:
Operator THER_LINEAIRE
Date:
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Author (S):
C. Key DURAND
:
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: 1/8
Organization (S): EDF-R & D/AMA
Handbook of Utilization
U4.5- booklet:Methods of resolution
Document: U4.54.01
Operator THER_LINEAIRE
1 Goal
To solve a linear problem of thermics in stationary regime or evolutionary.
The thermal loading is defined by key word CHARGE.
The temporal discretization of an evolutionary calculation is provided by the list of moments defined under the key word
LIST_INST. This calculation can be initialized, at the first moment, in three different ways (key word
TEMP_INIT):
· by a constant temperature,
· by a field of temperature, definite, or extracted as a preliminary from a preceding calculation,
· by a preliminary stationary calculation.
The concept produced by this operator is of evol_ther type.
When a calculation of sensitivity of the result compared to a parameter is required, there is production
of as many structures of data of the evol_ther type of necessary parameters.
Handbook of Utilization
U4.5- booklet: Methods of resolution
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Titrate:
Operator THER_LINEAIRE
Date:
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2 Syntax
temper
[evol_ther]
=
THER_LINEAIRE
(reuse
=
temper,
MODELE
=
Mo,
[model]
CHAM_MATER
=
chmat,
[cham_mater]
CARA_ELEM
=
carac,
[cara_elem]
EXCIT
= _F (
CHARGE
=
tank,
[load]
FONC_MULT
=
fonc,
[function]
),
TEMP_INIT =_F (
/STATIONNAIRE =
“YES”, [DEFECT]
/VALE
= tinit,
[R]
/
CHAM_NO =
tinit,
[cham_no_TEMP_R]
/
EVOL_THER = temp,
[evol_ther]
NUME_INIT = nuini_evol, [I]
),
SENSIBILITE=_F (
.
.
.
to see
[U4.50.02]
.
.
.
),
SENS_INIT =_F (
/STATIONNAIRE =
“YES”, [DEFECT]
/
EVOL_THER = temp,
[evol_ther]
NUME_INIT = nuini, [I]
),
INCREMENT =_F (
LIST_INST
=
litps,
[listr8]
NUME_INIT
=/0,
/
nuini,
[I]
NUME_FIN
=
nufin,
[I]
),
PARM_THETA
=
/theta,
[R]
/
0.57,
[DEFAUT]
SOLVEUR
=_F (
… to see [U4.50.01]…),
ARCHIVAGE
=_F
(/LIST_ARCH
= l_arch
, [listis]
/PAS_ARCH = ipas, [I]
/LIST_INST
= l_inst
, [listr8]
/INST = inst, [R]
PRECISION
=/
10.- 3, [DEFAUT]
/
prec
[R]
CRITERE =/
“RELATIF”,
[DEFAUT]
/
“ABSOLU”,
CHAM_EXCLU
= l_cham
, [l_Kn]
),
TITER
=
titrate,
[l_Kn]
)
Handbook of Utilization
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Code_Aster ®
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Titrate:
Operator THER_LINEAIRE
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3 Operands
3.1 Operand
MODELE
MODELE = Mo
Name of the model whose elements are the subject of thermal calculation.
3.2 Operand
CHAM_MATER
CHAM_MATER = chmat
Name of the affected material field on the model.
3.3 Operand
CARA_ELEM
CARA_ELEM = carac
The concept carac contains the characteristics of the elements of thermal hull, if they exist
in the model.
3.4 Word
key
EXCIT
EXCIT
=
Operand allowing to define several loadings. For each occurrence of the key word
factor, one defines a load possibly multiplied by a function of time.
3.4.1 Operand
CHARGE
CHARGE = tank
Concept of the type charges produces by AFFE_CHAR_THER or AFFE_CHAR_THER_F
[U4.44.02].
Important remark:
For each occurrence of the key word factor EXCIT the various concepts tank used
must be built on the same model Mo.
3.4.2 Operand
FONC_MULT
FONC_MULT = fonc
Multiplicative coefficient function of the time (concept of the function type) applied to the load.
Important remark:
The concomitant use of FONC_MULT with a load containing of
thermal loadings depending on the temperature is prohibited; i.e. for
loadings of the type ECHANGE_ *.
3.5 Word
key
TEMP_INIT
TEMP_INIT
=
Allows to define the initial field from which evolutionary calculation is carried out.
Note:
If key word TEMP_INIT misses, one carries out only stationary calculation with
the moment defined under key word INCREMENT.
The initial field is stored in the structure of data evol_ther result under
sequence number 0.
Handbook of Utilization
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3.5.1 Operand
STATIONNAIRE
/
STATIONNAIRE
=
“OUI”
The initial value of the field of temperature is then the result of a stationary calculation
precondition.
3.5.2 Operand
VALE
/
VALE
=
tinit
The initial value of temperature is taken constant on all the structure.
3.5.3 Operand
CHAM_NO
/
CHAM_NO
=
tinit
The initial value is defined by a cham_no_TEMP_R (result of the operators
AFFE_CHAM_NO [U4.44.11] or RECU_CHAMP [U4.71.01]).
3.5.4 Operand
EVOL_THER
/
EVOL_THER = temp
The initial value is extracted from a structure of data of the evol_ther type.
3.5.5 Operand
NUME_INIT
NUME_INIT = nuini_evol
Sequence number of the field to be extracted from this structure of data.
Note:
Attention, it acts of the sequence number in the structure of data read in recovery by
preceding key word EVOL_THER. If this structure of data were calculated with
a list of moments different from that used under the key word factor INCREMENT of
the current resolution, it is imperative to inform NUME_INIT under INCREMENT,
the same value of sequence number corresponding to physical moments
different. If the two lists of moments are identical, one can
to exempt to inform the same NUME_INIT twice, under ETAT_INIT and under
INCREMENT.
3.6 Word
key
SENSIBILITE
SENSIBILITE = sensitive parameter list
Activate the calculation of derived from the field of temperature compared to a significant parameter
problem.
The document [U4.50.01] specifies the operation of the key word.
3.7 Word
key
SENS_INIT
SENS_INIT
=
Allows to define the initial field from which the evolutionary calculation of derived from
temperature is carried out, for a transitory calculation.
Note:
If key word SENS_INIT misses, initialization is made by a field with the nodes
no one.
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3.7.1 Operand
STATIONNAIRE
/
STATIONNAIRE
=
“OUI”
The initial value is that of a preliminary stationary calculation. That is not possible that if it
even mode of initialization is retained for the calculation of the temperature.
3.7.2 Operand
EVOL_THER
/
EVOL_THER = temp
The initial value is extracted from a structure of data of the evol_ther type.
3.7.3 Operand
NUME_INIT
NUME_INIT = nuini_evol
Sequence number of the field to be extracted from this structure of indicated data.
3.8 Word
key
INCREMENT
INCREMENT =
Allows to define the moments of calculation which determine the intervals of time taken to integrate
the differential equation.
Note:
If key word INCREMENT misses, one creates a list of moments reduced to the only reality
0 and one carry out a stationary calculation.
3.8.1 Operand
LIST_INST
LIST_INST = litps
List moments, produced by DEFI_LIST_REEL [U4.34.01].
3.8.2 Operand
NUME_INIT
NUME_INIT =/0
/nuini
Index of the moment of starting calculation in the list litps.
3.8.3 Operand
NUME_FIN
NUME_FIN = nufin
Index of the moment of final calculation in the list litps.
The moments of calculation are those defined in the concept litps taken between the nuini and it
nufin which is numbers of moment. Thus the first step of time is defined between the moment
correspondent with nuini and that corresponding to nuini + 1. Stationary calculation, when it
is asked, is made at the moment corresponding to nuini.
If NUME_INIT misses and if temp is present under TEMP_INIT, then
nuini = nuini_evol.
Handbook of Utilization
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3.9 Operand
PARM_THETA
PARM_THETA
=
The argument theta is the parameter of the théta-method applied to the evolutionary problem. It must
to lie between 0 (explicit method) and 1 (completely implicit method). In the absence, word
key, the value used is theta=0.57, a little higher than theta=0.5 corresponding to the diagram
of Crank-Nicholson. The incidence of the choice of theta on the stability of the method is detailed
in [R5.02.02].
3.10 Word
key
SOLVEUR
SOLVEUR =
This key word factor is optional: it makes it possible to define the method of resolution of the systems
linear.
This operand is common to the whole of the total commands [U4.50.01].
3.11 Word
key
ARCHIVAGE
ARCHIVAGE
=
This key word is optional: by defect, the whole of the computed fields for all the calculated steps
is filed in the concept result resulting from the command. It is used to store certain numbers
of command in a structure of data result and/or to exclude from storage certain fields.
Note:
In the event of stop of calculation for lack of time CPU, steps of time previously
calculated are backed up in the base.
3.11.1 Operand LIST_ARCH
Concept of the type lists of entirety created by command DEFI_LIST_ENTI [U4.34.02] describing the list
sequence numbers having to be stored in the structure of data result.
3.11.2 Operand PAS_ARCH
Whole value giving the value of step of filing: one will store the multiple sequence numbers of
value ipas as well as the last actually calculated sequence number.
3.11.3 Operand CHAM_EXCLU
List texts indicating the fields excluded from filing. The list of the possible fields is
described in the documents on the concepts result [U5.01].
3.12 Operand
TITER
TITER
=
titrate
Titrate that one wants to give to the result temp stored in the structure of data of the type
evol_ther [U4.03.01].
4 Modeling
The problems of linear thermics can be dealt with with models using the finite elements
3D, 2D, AXIS or COQUE described in the documents [U3.22.01], [U3.23.01], [U3.23.02] and [U3.24.01].
Handbook of Utilization
U4.5- booklet: Methods of resolution
HT-66/05/004/A
Code_Aster ®
Version
8.1
Titrate:
Operator THER_LINEAIRE
Date:
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Author (S):
C. Key DURAND
:
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5 Example
5.1 Calculation
transient
LR8 = DEFI_LIST_REEL (BEGINNING
=
0.E0
,
INTERVALLE
= (
_F (JUSQU_A = 2.E-4, A NUMBER
= 2),
_F (JUSQU_A = 1.E-3, A NUMBER
= 10
),
_F (JUSQU_A = 1.E-2, A NUMBER
= 9),
_F (JUSQU_A = 1.E-1, A NUMBER
= 9),
_F (JUSQU_A = 1.E+0, A NUMBER
= 9),
_F (JUSQU_A = 2.0
, NOMBRE
= 10
),)
)
temple = THER_LINEAIRE
(MODELE
= moth,
CHAM_MATER = chmat,
EXCIT
= _F (CHARGE
=
chth),
TEMP_INIT
=
_F (
STATIONNAIRE = “yes”),
INCREMENT
=
_F (
LIST_INST
= lr8,
NUME_FIN
= 30)
)
temple = THER_LINEAIRE
(reuse = temple,
MODELE
=
moth,
CHAM_MATER = chmat,
EXCIT
= _F (CHARGE
=
chth),
TEMP_INIT
=
_F (
EVOL_THER
= temple
NUME_INIT
= 30),
INCREMENT
=
_F (
LIST_INST
= lr8),
)
The first call to command THER_LINEAIRE makes it possible to carry out a stationary calculation at the moment
0. and to connect an evolutionary calculation until the moment 0.1s (31 moments of calculation is 30 calculations
of evolution).
The second call makes it possible to enrich the concept temple precedent, evolutionary calculation is continued to leave
31ième moment of calculation.
5.2
Sensitivity to an imposed temperature
your
= DEFI_PARA_SENSI (VALE = 70
)
Tb
= DEFI_PARA_SENSI (VALE = 30
)
Ca
= AFFE_CHAR_THER_F
(MODELE
= moth,
TEMP_IMPO
= (
_F (
GROUP_MA = “bord_sup”,
TEMP
= your),
_F (GROUP_MA = “bord_inf”,
TEMP
= Tb))
)
temple = THER_LINEAIRE
(MODELE
= moth,
CHAM_MATER = chmat,
EXCIT
=_F (CHARGE
=
chth),
SENSIBILITE=
(
your
,
Tb
),
)
This calculation will produce the structure of data temple, evol_ther type, containing the field of
temperature under name TEMP. It will produce also two other structures of the evol_ther type.
first will contain, under the name of field TEMP, the field of derived from the temperature by
report/ratio with the parameter your. The second will contain the derivative compared to the parameter Tb. The name of
these structures is created automatically by the code and remains unknown to the user. The access to their
contents (impression, test, post_releve…) is done by calling upon the corresponding command with
name of the principal structure, temp, and the name of the significant parameter concerned, your or Tb.
Handbook of Utilization
U4.5- booklet: Methods of resolution
HT-66/05/004/A
Code_Aster ®
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Titrate:
Operator THER_LINEAIRE
Date:
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Author (S):
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:
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6 Remark
Command CALC_ELEM [U4.81.01] makes it possible to calculate the heat flows, at the points of integration
or with the nodes, the field with the nodes of temperature thus obtained by THER_LINEAIRE.
Handbook of Utilization
U4.5- booklet: Methods of resolution
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