/GRAV

Format

(1)	(2)	(3)	(4)	(5)	(7)	(9)
/GRAV/`grav_ID`/`unit_ID`
`grav_title`
`fct_ID`_T	`Dir`	`skew_ID`	`sens_ID`	`grnd_ID`	`Ascale`_x	`Fscale`_Y

Definitions

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_ID`_T	Time function identifier. 3 = 0 (Default) A constant gravity defined in `Fscale`_Y is applied. > 0 The applied gravity is time dependent. (Integer)
`Dir`	Direction in translation (input should be: X, Y or Z). Default = Z (Text)
`skew_ID`	Skew identifier. (Integer)
`sens_ID`	Sensor identifier. ≠ 0 The gravity load is applied after sensor activation (the time function is shifted in time). (Integer)
`grnd_ID`	Node group to which the gravity load is applied. Default = 0 (See Comment 2) (Integer)
`Ascale`_x	Abscissa (time) scale factor. Default = 1.0 (Real)	$[s]$
`Fscale`_Y	If `fct_ID`_T = 0: A constant gravity value is applied. If `fct_ID`_T > 0: Ordinate (force) scale factor. Default = 1.0 (Real)	$[\frac{m}{s^{2}}]$

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 â€“ 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 specifc group of nodes by defining grnd_ID.
If function fct_ID_T =0 or is blank, the gravity load is a constant value $g (t) = F s c a l e_{y}$ .
Otherwise, if the function fct_ID_T is defined, the actual load function value is calculated as: (1)
$g (t) = F s c a l e_{y} \cdot f_{t} \cdot (\frac{t}{A s c a l e_{x}})$

Where, $f_{T}$ is the function of fct_ID_T.

/GRAV applies to each node and is stated as force:(2)
$F (t) = m \cdot g (t)$

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 Fscale_Y without fct_ID_T or by referencing a constant function from t=0 in fct_ID_T.

Figure 1.