/LOAD/PFLUID
Block Format Keyword This entry provides a simple way to simulate hydrodynamic fluid pressure on a structure. The fluid pressure is calculated according to the specified fluid velocity, orientation of the structural surface against the fluid vector and the height of the fluid column above the surface of the structure.
Format
(1)  (2)  (3)  (4)  (5)  (6)  (7)  (8)  (9)  (10) 

/LOAD/PFLUID/load_ID/unit_ID  
load_title  
surf_ID  sens_ID  
fct_hsp  Ascalex_hsp  Fscaley_hsp  
Dir_hsp  frahsp_ID  
fct_pc  Ascalex_pc  Fscaley_pc  
fct_vel  Ascalex_vel  Fscaley_vel  
Dir_vel  fravel_ID 
Definition
Field  Contents  SI Unit Example 

load_ID  Load block
identifier. (Integer, maximum 10 digits) 

unit_ID  Unit Identifier. (Integer, maximum 10 digits) 

load_title  Load block title. (Character, maximum 100 characters) 

surf_ID  Surface
identifier. (Integer) 

sens_ID  Sensor
identifier. (Integer) 

fct_hsp  Hydrostatic pressure as a
function of the fluid column height above the structural
surface. (Integer) 

Ascalex_hsp  Abscissa scale factor for
fct_hsp. Default = 1.0 (Real) 
$\left[\text{s}\right]$ 
Fscaley_hsp  Ordinate scale factor for
fct_hsp. Default = 1.0 (Real) 
$\left[\text{Pa}\right]$ 
Dir_hsp  Vertical (gravitational)
direction of the water column above the structural surface (input X, Y or
Z). (Text) 

frahsp_ID  Frame identifier for the vertical
(gravitational) direction of the water column above the structural
surface. (Integer) 

fct_pc  Hydrodynamic drag coefficient as
a function of time. 4 (Integer) 

Ascalex_pc  Abscissa scale factor for
fct_pc. Default = 1.0 (Real) 
$\left[\text{s}\right]$ 
Fscaley_pc  Ordinate scale factor for
fct_pc. Default = 1.0 (Real) 
$\left[\frac{\text{kg}}{{\text{m}}^{\text{3}}}\right]$ 
fct_vel  Fluid velocity as a function of
time. (Integer) 

Ascalex_vel  Abscissa scale factor for
fct_vel. Default = 1.0 (Real) 
$\left[\text{s}\right]$ 
Fscaley_vel  Ordinate scale factor for
fct_vel. Default = 1.0 (Real) 
$\left[\frac{\text{m}}{\text{s}}\right]$ 
Dir_vel  Direction of fluid velocity
(input X, Y or Z). (Text) 

fravel_ID  Frame identifier for the fluid
velocity direction. (Integer) 
Example (Wind Effect)
#RADIOSS STARTER
#12345678910
/UNIT/1
unit for load
# MUNIT LUNIT TUNIT
kg mm ms
#12345678910
/LOAD/PFLUID/1/1
Wind effect
# surf_ID sens_ID
8 0
# fct_hsp Ascalex_hsp Fscaley_hsp
0 0 0
# Dir_hsp frahsp_ID
0
# fct_pc Ascalex_pc Fscaley_pc
2 0 2
# fct_vel Ascalex_vel Fscaley_vel
3 0 15
# Dir_vel fravel_ID
Y 0
#12345678910
/FUNCT/2
Air density
# X Y
0 1.2E9
1000 1.2E9
#12345678910
/FUNCT/3
Air velocity
# X Y
0 1
1000 1
#12345678910
#ENDDATA
Comments
 The fluid pressure applied to each
element of the structural surface is computed as:
(1) $$P=\rho gh+\frac{{\mathrm{V}}^{2}(t)\left(\rho \mathrm{D}(t)\right)}{2}$$Where, $\rho $
 Fluid density
 $g$
 Acceleration due to gravity
 $h$
 Height of the water column above an element of the structural surface
 $\mathrm{V}(t)$
 Relative fluid velocity which is normal to the element of the structural surface
 $\mathrm{D}(t)$
 Drag coefficient for complete structural surface
 The value of hydrostatic pressure ( $\rho gh$ ) as a function of fluid column height ($h$ ) above the structural surface is stated using the function fct_hsp. If this is not defined (=0), the effect is not accounted for (fct_hsp(altitude)=0).
 Hydrodynamic pressure is calculated
with respect to the relative orientation of the fluid vector and the element
normal.
(2) $$\mathrm{V}(t)=\left\left(\left({V}_{fluid}{V}_{element}\right),n\right)\right$$Where, ${V}_{fluid}$
 Specified fluid velocity (fct_vel(t)). If not defined (=0), the effect of fluid velocity is not accounted for ( $\mathrm{V}(t)$ = 0)
 ${V}_{element}$
 Element velocity
 $n$
 Element normal
 fct_pc defines the value of $\rho \mathrm{D}(t)$ as a function of time. If this is not defined, the effect of fluid velocity is not accounted for.