Code_Aster ®
Version
7.4
Titrate:
Operator AFFE_CHAR_ACOU
Date:
20/12/04
Author (S):
NR. GREFFET, F. STIFKENS Key
:
U4.44.04-G Page
: 1/4
Organization (S): EDF-R & D/AMA
Handbook of Utilization
U4.4- booklet: Modeling
Document: U4.44.04
Operator AFFE_CHAR_ACOU
1 Goal
To affect boundary conditions acoustic constant. The affected values do not depend
of any parameter and are complex values.
Product a structure of data of the char_acou type.
Handbook of Utilization
U4.4- booklet: Modeling
HT-66/04/004/A
Code_Aster ®
Version
7.4
Titrate:
Operator AFFE_CHAR_ACOU
Date:
20/12/04
Author (S):
NR. GREFFET, F. STIFKENS Key
:
U4.44.04-G Page
: 2/4
2 Syntax
CH [char_acou] = AFFE_CHAR_ACOU
(
MODELE
=
Mo
[model]
VERI_DDL
=
/
“YES” [DEFECT]
/
“NON”
I PRES_IMPO
= F (
I
ALL = “YES”
I
NOEUD
= lno
[l_noeud]
I
GROUP_NO = lgno [l_gr_noeud]
I
MAILLE
=
lma [l_maille]
I
GROUP_MA = lgma [l_gr_maille]
PRES =
pre
[C]
)
I VITE_FACE
= _F (
/
ALL = “YES”
/
MAILLE
=
lma [l_maille]
/
GROUP_MA = lgma [l_gr_maille]
VNOR =
vn
[C]
)
I IMPE_FACE
= _F (
/
ALL = “YES”
/
MAILLE
=
lma [l_maille]
/
GROUP_MA = lgma [l_gr_maille]
IMPE =
Z
[C]
)
I LIAISON_UNIF=
_F (
/
NOEUD
= lno
[l_noeud]
/
GROUP_NO = lgno [l_gr_noeud]
/
MAILLE
=
lma [l_maille]
/
GROUP_MA = lgma [l_gr_maille]
DDL =
“PRES”
)
);
Handbook of Utilization
U4.4- booklet: Modeling
HT-66/04/004/A
Code_Aster ®
Version
7.4
Titrate:
Operator AFFE_CHAR_ACOU
Date:
20/12/04
Author (S):
NR. GREFFET, F. STIFKENS Key
:
U4.44.04-G Page
: 3/4
3 Operands
3.1 Operand
MODELE
MODELE = Mo
Name of the model whose grid supports the elements of acoustic calculation.
3.2 Operand
VERI_DDL
VERI_DDL =/“YES”
/
“NON”
Allows to check that the DDLs goods are well presented, i.e. here DDL “PRES”
(cf [§3.4]).
3.3 Words
keys
PRES_IMPO/VITE_FACE/IMPE_FACE
3.3.1 Drank
Key words factors giving it natural of the conditions imposed on the specified elements (nodes, or
groups of nodes, meshs or groups of meshs).
I
PRES_IMPO
Allows to impose the DDL of pressure.
I VITE_FACE
Allows to specify the vibratory field speed imposed in loading on elements
of border.
I IMPE_FACE
Allows to specify the card of impedance imposed in boundary condition on elements
of border.
3.3.2 Operands
ALL/NODE/GROUP_NO/MESH/GROUP_MA
Declaration of the topological entities to which the loadings are applied, conditions with
limits.
Handbook of Utilization
U4.4- booklet: Modeling
HT-66/04/004/A
Code_Aster ®
Version
7.4
Titrate:
Operator AFFE_CHAR_ACOU
Date:
20/12/04
Author (S):
NR. GREFFET, F. STIFKENS Key
:
U4.44.04-G Page
: 4/4
3.3.3 Operands
CLOSE/VNOR/IMPE
PRES = pre
Value (complex) of the acoustic DDL of pressure (only DDL in acoustic modeling)
imposed on the nodes or groups of specified nodes.
VNOR = vn
Value (complex) of the component on the normal external with the meshs or groups of meshs
specified, the vibratory speed of the fluid.
IMPE = Z
Value (complex) of the acoustic impedance imposed on the meshs or groups of meshs
specified.
3.4 Word
key
LIAISON_UNIF
3.4.1 Drank
Key word factor allowing to impose the same value (unknown) on degrees of freedom of one
together of nodes.
3.4.2 Operands
NET/GROUP_MA/NODE/GROUP_NO
These operands make it possible to define a list of N nodes Nor from which one eliminated the redundancies
(for MAILLE and GROUP_MA, they are connectivities of the meshs).
3.4.3 DDL
This operand can be worth in acoustic modeling, only text “PRES”, defining only
degree of freedom allowed, acoustic pressure p.
The resulting imposed conditions are:
(pN1) = (pN) for I {2,…,} N
I
4 Example
cha = AFFE_CHAR_ACOU (MODELE = Mo,
VITE_FACE
=
_F (
MAILLE
=
m4
,
VNOR = (“IH”, 0.0135, 0. )),
IMPE_FACE
=
_F (
MAILLE
=
m5
,
IMPE = (“IH”, 442. , 0. )))
Note:
The complex values are provided under one of two forms IH (left real, left
imaginary) or MP (module, phase in degrees).
Handbook of Utilization
U4.4- booklet: Modeling
HT-66/04/004/A
Outline document