#### INITIAL_VELOCITY

###### Initial conditions
*INITIAL_VELOCITY
entype, enid, $v_{x0}$, $v_{y0}$, $v_{z0}$, $\omega_x$, $\omega_y$, $\omega_z$
$x_0$, $y_0$, $z_0$, $\delta v_x$, $\delta v_y$, $\delta v_z$, csysid
##### Parameter definition
VariableDescription
entype Entity type
options: N, NS, P, PS, ALL, G
enid Entity identification number
$v_{x0}$ Initial velocity in x-direction
options: constant, fcn
default: 0
$v_{y0}$ Initial velocity in y-direction
options: constant, fcn
default: 0
$v_{z0}$ Initial velocity in z-direction
options: constant, fcn
default: 0
$\omega_x$, $\omega_y$, $\omega_z$ Initial angular velocity vector
default: (0,0,0)
$x_0$, $y_0$, $z_0$ Center of rotation
default: (0,0,0)
$\delta v_x$, $\delta v_y$, $\delta v_z$ Gradient of velocity field
default: (0,0,0)
csysid Optional local coordinate system ID
default: not used
##### Description

This command is used to define initial velocities and initial angular velocities, applying to nodes and to soil particles (see PARTICLE_SOIL). The command is additive and multiple velocity definitions are summed up to form a total velocity.

An initial velocity term of a node or a soil particle at coordinate $(x,y,z)$ is defined as:

$\left\{ \begin{array}{c} v_x \\ v_y \\ v_z \end{array} \right\} = \left\{ \begin{array}{c} v_{x0} \\ v_{y0} \\ v_{z0} \end{array} \right\} + \left\{ \begin{array}{c} x-x_0 \\ y-y_0 \\ z-z_0 \end{array} \right\} \times \left\{ \begin{array}{c} \omega_x \\ \omega_y \\ \omega_z \end{array} \right\} + \left\{ \begin{array}{c} \delta v_x (x-x_0) \\ \delta v_y (y-y_0) \\ \delta v_z (z-z_0) \end{array} \right\}$
##### Example
###### Initial velocity

The command below initializes the spin of rigid body with part id 333. The axis of rotation is defined from the spin vector (10,20,0) and the point (1,2,3).

*INITIAL_VELOCITY
P, 333, 0.0, 0.0, 0.0, 10.0, 20.0, 0.0
1.0, 2.0, 3.0
###### Initial velocity field using fcn

Complete command file of a rubber sheet that has been assigned a linear velocity field.

*UNIT_SYSTEM
SI
*TIME
0.01
*COMPONENT_BOX
1, 1, 10, 5, 1
-0.1, 0, 0, 0.1, 0.1, 0.001
*CHANGE_P-ORDER
ALL, 0, 3
*MAT_MOONEY_RIVLIN
1, 2000.0, 1.0e9
2.0e5, 2.0e5
*PART
"rubber sheet"
1, 1
*INITIAL_VELOCITY
P, 1, fcn(22)
*FUNCTION
22
100*x
*END