/RWALL
Block Format Keyword Defines the following types of rigid walls: Infinite Plane, Infinite Cylinder, Sphere and Parallelogram.
Format
(1)  (2)  (3)  (4)  (5)  (6)  (7)  (8)  (9)  (10) 

/RWALL/type/rwall_ID/unit_ID  
rwall_title  
node_ID  Slide  grnd_ID_{1}  grnd_ID_{2}  
D_{search}  fric  $\varphi $  ffac  ifq 
(1)  (2)  (3)  (4)  (5)  (6)  (7)  (8)  (9)  (10) 

X_{M}  Y_{M}  Z_{M} 
(1)  (2)  (3)  (4)  (5)  (6)  (7)  (8)  (9)  (10) 

Mass  VX_{0}  VY_{0}  VZ_{0} 
(1)  (2)  (3)  (4)  (5)  (6)  (7)  (8)  (9)  (10) 

X_{M1}  Y_{M1}  Z_{M1} 
(1)  (2)  (3)  (4)  (5)  (6)  (7)  (8)  (9)  (10) 

X_{M2}  Y_{M2}  Z_{M2} 
Definitions
Field  Contents  SI Unit Example 

type  Rigid wall type
keyword (see table below) 

rwall_ID  Rigid wall
identifier (Integer, maximum 10 digits) 

unit_ID  Unit Identifier (Integer, maximum 10 digits) 

rwall_title  Rigid wall
title (Character, maximum 100 characters) 

node_ID  Node identifier (moving
rigid wall) (Integer) 

Slide  Sliding flag.
(Integer) 

grnd_ID_{1}  Node group defining
secondary nodes to be added to the rigid
wall. (Integer) 

grnd_ID_{2}  Node group defining
secondary nodes to be deleted from the rigid
wall. (Integer) 

D_{search}  Distance for secondary
search. (Real) 
$\left[\text{m}\right]$ 
fric  Friction. (Real) 

$\varphi $  Diameter of the
sphere. (Real) 
$\left[\text{m}\right]$ 
ffac  Filtering factor. The default value depends on the ifq flag (Real) 

ifq  Filtering flag. 5
Default = 0 (Integer) 

X_{M}  X coordinate of
M (Real) 

Y_{M}  Y coordinate of
M (Real) 

Z_{M}  Z coordinate of
M (Real) 

Mass  Mass of the rigid wall.
8 If no mass is entered, the rigid wall will have a constant imposed velocity. (Real) 
$\left[\text{kg}\right]$ 
VX_{0}  Initial velocity in X
direction (Real) 
$\left[\frac{\text{m}}{\text{s}}\right]$ 
VY_{0}  Initial velocity in Y
direction (Real) 
$\left[\frac{\text{m}}{\text{s}}\right]$ 
VZ_{0}  Initial velocity in Z
direction (Real) 
$\left[\frac{\text{m}}{\text{s}}\right]$ 
X_{M1}  X coordinate of
M1 (Real) 

Y_{M1}  Y coordinate of
M1 (Real) 

Z_{M1}  Z coordinate of
M1 (Real) 

X_{M2}  X coordinate of
M2 (Real) 

Y_{M2}  Y coordinate of
M2 (Real) 

Z_{M2}  Z coordinate of
M2 (Real) 
Rigid Wall Type
 Type
 Description
 PLANE
 $\overline{\infty}$ plane
 CYL
 $\overline{\infty}$ Cylinder of diameter $\varphi $
 SPHER
 Sphere of diameter $\varphi $
 PARAL
 Parallelogram
Surface Input Type
 Type
 Description
 PLANE
 MM1 defines the normal direction
 CYL
 MM1 defines the axis of the cylinder
 SPHER
 M is the center of the sphere
 PARAL
 $MM1$ and $MM2$ define the parallelogram
Comments
 The first input defines the rigid wall coordinates of one point M or a node_ID in case of moving rigid wall.
 The next input is the coordinate of a point M1 and possibly a point M2 (in case of a moving wall, M1 and M2 have the same motion as node_ID).
 The secondary nodes to a rigid wall can be defined as a group of nodes and/or as nodes initially at a distance less than the distance (D_{search}) from the rigid wall.
 The friction filtering option is only available for a slide rigid wall with friction (Slide =2).
 Filtering flag
ifg
If ifq ≠ 0, the tangential (friction) forces in each secondary node in contact are filtered using a simple rule:
(1) $${F}_{Tf}=\alpha {F}_{T}(t)+\left(1\alpha \right){F}_{Tf}(tdt)$$Where, ${F}_{Tf}$
 Filtered tangential force.
 ${F}_{T}(t)$
 Calculated tangential force at time t before filtering.
 ${F}_{Tf}(tdt)$
 Filtered tangential force at the previous time step
 $t$
 Current simulation time
 $dt$
 Current simulation time step
 $\alpha $
 Filtering coefficient
The flag ifq defines a method for filtering, α coefficient.
If ifq =1, filtering coefficient is directly input by you: $\alpha =ffac$
If ifq =2, α corresponds to a 3dB filtering level for userdefined frequency (frequency defined in terms of time step number):(2) $$\alpha =\frac{2\pi}{N}$$with $\frac{1}{freq}=T=Ndt$ , and $N=ffac$
If ifq =3, α corresponds to a 3dB filtering level for userdefined frequency:(3) $$\alpha =2\pi dt\cdot freq$$Where, $dt$
 Time step
 $freq$
 ffac
 The sphere (SPHER) and parallelogram
(PARAL) are not infinite. For parallelograms, the normal is defined
using:
(4) $$MM1\times MM2$$and the diameter of the sphere is defined using $\varphi $ .
 Nodal thickness of rigid wall secondary nodes is not taken into account.
 For moving rigid walls with MASS=0 or blank, the rigid wall will have a constant imposed velocity and not an initial velocity.