Code_Aster ®
Version
8.2
Titrate:
Operator CALC_FLUI_STRU
Date:
31/01/06
Author (S):
A. Key ADOBES
:
U4.66.02-G1 Page:
1/4
Organization (S): EDF-R & D/MFTT
Handbook of Utilization
U4.6- booklet: Elementary matrices/Vecteurs and assembly
Document: U4.66.02
Operator CALC_FLUI_STRU
1 Goal
To calculate the modal parameters of a structure subjected to a flow. Allows to hold account
forces fluid-rubber bands which are represented by a matrix of transfer complexes connecting them
with modal displacements. For certain configurations, the matrix of transfer can be
broken up into three real matrices of coefficients of mass, damping and rigidity added.
The disturbances of the modal characteristics of the complex structure depend on the speed of
the flow. Thus the terms of the matrix of transfer of the efforts fluid-rubber bands depend on
speed of the fluid and the frequency of the movement via the parameter fallback speed
Vr = V/(f.D).
The operator calculates a modal base modified by coupling, for each mean velocity of the fluid
studied. The produced concept is of melasflu type.
Handbook of Utilization
U4.6- booklet: Elementary matrices/Vecteurs and assembly
HT-62/06/004/A
Code_Aster ®
Version
8.2
Titrate:
Operator CALC_FLUI_STRU
Date:
31/01/06
Author (S):
A. Key ADOBES
:
U4.66.02-G1 Page:
2/4
2 Syntax
melf
[melasflu] = CALC_FLUI_STRU
(
VITE_FLUI
= _F
(
VITE_MIN
=
VI
, [R]
VITE_MAX
=
VM
, [R]
NB_POIN = Np
, [I]
),
BASE_MODALE
=
_F (
MODE_MECA
=
mode
,
[mode_meca]
NUME_ORDRE = l_nuor
,
[l_I]
/AMOR_REDUIT = l_amor
, [l_R]
/
AMOR_UNIF
=
amor
,
[R]
AMOR_REDUIT_CONN = l_amor_c,
[l_R]
),
TYPE_FLUI_STRU
=
typeflui
, [type_flui_stru]
IMPRESSION = _F (
PARA_COUPLAGE
=
/
“YES” [DEFECT]
/
“NON”
,
DEFORMEE
=
/
“NOT” [DEFECT]
/
“OUI”
,
),
);
Handbook of Utilization
U4.6- booklet: Elementary matrices/Vecteurs and assembly
HT-62/06/004/A
Code_Aster ®
Version
8.2
Titrate:
Operator CALC_FLUI_STRU
Date:
31/01/06
Author (S):
A. Key ADOBES
:
U4.66.02-G1 Page:
3/4
3 Operands
3.1 Key word
VITE_FLUI
VITE_FLUI
Key word factor which makes it possible to define the range studied fluid speeds and discretization.
VITE_MIN = VI
First value the speed for which the parameters of coupling will be calculated.
VITE_MAX=
VM
Last value the speed for which the parameters of coupling will be calculated.
NB_POIN=
Np
The number of points defines of speed (the step of discretization is constant).
3.2 Key word
BASE_MODALE
BASE_MODALE
Key word factor which makes it possible to define the modal base of concept mode_meca for which
parameters of coupling are calculated. The coupling modifies the Eigen frequencies and the terms
of damping reduces associated with each mode (key word AMOR_REDUIT or AMOR_UNIF).
MODE_MECA = mode
Modal base of type of concept mode_meca.
NUME_ORDRE = l_nuor
Allows to select the modes of the modal base of mode_meca type to be taken in
count for the calculation of the coupling.
/AMOR_REDUIT = l_amor
List reduced depreciation (percentage of damping criticizes)
correspondent with each mode of the structure.
Note:
They must be in a number identical to the number of modes taken into account (these
modes are defined by key word NUME_ORDRE).
/AMOR_UNIF = amor
One applies to all the modes of the modal base same reduced damping.
AMOR_REDUIT_CONN = l_amor_c
List reduced depreciation (percentage of damping criticizes)
correspondent with each mode of the structure for the method of Connors
(see [R4.07.04]).
Note:
As for key word AMOR_REDUIT, they must be in a number identical to
a number of modes taken into account.
Handbook of Utilization
U4.6- booklet: Elementary matrices/Vecteurs and assembly
HT-62/06/004/A
Code_Aster ®
Version
8.2
Titrate:
Operator CALC_FLUI_STRU
Date:
31/01/06
Author (S):
A. Key ADOBES
:
U4.66.02-G1 Page:
4/4
3.3 Key word
TYPE_FLUI_STRU
TYPE_FLUI_STRU = typeflui
Concept of the type_flui_stru type. It makes it possible to define the studied configuration, i.e. them
coefficients of coupling used for the modeling of the forces fluid-rubber bands.
Note:
In the case of a configuration of the type “beam of tubes under axial flow”
(key word factor FAISCEAU_AXIAL), the calculation of the parameters of coupling of
structure with the fluid in at-rest state, is taken into account. This calculation is carried out
whatever the fluid range speed that the user informed by the key word
VITE_FLUI.
In this case of fluid at rest, the matrix of transfer representing the force
fluid-rubber band exerted on the structure, is put in the shape of a matrix
of added damping.
3.4 Key word
IMPRESSION
IMPRESSION
Key word factor allowing the user to choose information which it wishes to make write in
file RESULTAT.
PARA_COUPLAGE
= “OUI” or “NON”
By this key word, the user can ask for the impression of tables of results giving for
each mode evolutions fallback speed, frequency and reduced damping
modal according to the rate of flow of the fluid. The default value is “OUI”.
DEFORMEE = “OUI” or “NON”
By this key word the user can request the impression from format “RESULTAT” of the fields
displacements corresponding to the modal deformations. The default value is “NON”.
4 Remarks
In the case of a configuration of the type “beams of tubes under transverse flow”, it is
possible to define several zones of interaction enters the fluid and the structure, each one of these zones
being modélisable independently others. The calculation of the modal parameters of the structure
subjected to a flow takes then account of each one of these zones, defined explicitly in
order DEFI_FLUI_STRU [U4.25.01].
The concept produced by CALC_FLUI_STRU contains, in the form of table, the matrices of mass,
of damping and rigidity for each speed of fluid. The table, representing the modal base
modified, can be recovered by RECU_TABLE in order to be injected into a calculation
DYNA_TRAN_MODAL. This sequence of calculation is implemented in the case test SDLL118A.
Handbook of Utilization
U4.6- booklet: Elementary matrices/Vecteurs and assembly
HT-62/06/004/A
Outline document