/GRAV
Block Format Keyword Defines gravity load on node group.
Format
(1) | (2) | (3) | (4) | (5) | (6) | (7) | (8) | (9) | (10) |
---|---|---|---|---|---|---|---|---|---|
/GRAV/grav_ID/unit_ID | |||||||||
grav_title | |||||||||
fct_IDT | Dir | skew_ID | sens_ID | grnd_ID | Ascalex | FscaleY |
Definition
Field | Contents | SI Unit Example |
---|---|---|
grav_ID | Gravity load block
identifier. (Integer, maximum 10 digits) |
|
unit_ID | Unit Identifier. (Integer, maximum 10 digits) |
|
grav_title | Gravity load block
title. (Character, maximum 100 characters) |
|
fct_IDT | Time function identifier.
3
(Integer) |
|
Dir | Direction in translation
(input should be: X, Y or Z). Default = Z (Text) |
|
skew_ID | Skew
identifier. (Integer) |
|
sens_ID | Sensor identifier.
(Integer) |
|
grnd_ID | Node group to which the
gravity load is applied. Default = 0 (See Comment 2) (Integer) |
|
Ascalex | Abscissa (time) scale
factor. Default = 1.0 (Real) |
|
FscaleY | If
fct_IDT =
0: A constant gravity value is applied. If fct_IDT > 0: Ordinate (force) scale factor. Default = 1.0 (Real) |
Example
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
/UNIT/1
unit for load
# MUNIT LUNIT TUNIT
g mm ms
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
/INIGRAV/1/1
hydrostatique pressure – sea level : {Z=0} where Pref=0.101325 MPa
#GRPART_ID SURF_ID GRAV_ID
0 0 1
# Pref Bx By Bz
0.101325 0 0 0
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
/GRAV/1/1
Terrestrial gravity field
#funct_IDT DIR skew_ID sensor_ID grnod_ID Ascale_x Fscale_Y
2 Z 0 0 5 0 -0.00981
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
/FUNCT/2
unity
# X Y
0 1.0
1000000 1.0
#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|
#enddata
Comments
- The gravity load direction must be right justified in the ten characters of field number 2.
- By default, the gravity loads are applied to all the nodes in the model. The gravity loads can be applied to a specific group of nodes by defining grnd_ID.
- If function
fct_IDT
=0 or is blank, the gravity load is a constant value
.Otherwise, if the function fct_IDT is defined, the actual load function value is calculated as:
(1) Where, is the function of fct_IDT.
/GRAV applies to each node and is stated as force:(2) With m being the mass of node. The node will be moving until a force balance reached.
- If the gravity card is referenced by an /INIGRAV card for hydrostatic pressure initialization in a fluid-structure interaction simulation, the applied gravity must be constant be a constant value by defining FscaleY without fct_IDT or by referencing a constant function from t=0 in fct_IDT.