# /INIVEL/AXIS

Block Format Keyword Initialize both translational and rotational velocities on a group of nodes in a given coordinate system.

## Format

(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
/INIVEL/AXIS/inivel_ID/unit_ID
inivel_axis_title
Dir frame_ID grnd_ID
Vxt Vyt Vzt Vr

## Definition

Field Contents SI Unit Example
inivel_ID Initial velocity block identifier.

(Integer, maximum 10 digits)

unit_ID Unit Identifier.

(Integer, maximum 10 digits)

inivel_axis_title Initial velocity block title.

(Character, maximum 100 characters)

Dir Direction X, Y, and Z of the frame defining the rotation axis.

(Text)

frame_ID Frame identifier. frame_ID is obligatory input.

If not given, the initial velocities are applied with respect to the global coordinate system.

(Integer)

grnd_ID Node group on which specified initial velocities are applied.

(Integer)

Vxt X component in the local frame of the translational velocity.

(Real)

$\left[\frac{\text{m}}{\text{s}}\right]$
Vyt Y component in the local frame of the translational velocity.

(Real)

$\left[\frac{\text{m}}{\text{s}}\right]$
Vzt Z component in the local frame of the translational velocity.

(Real)

$\left[\frac{\text{m}}{\text{s}}\right]$
Vr Rotational velocity about the rotational axis.

(Real)

$\left[\frac{\text{rad}}{\text{s}}\right]$

1. The keyword defines initial rigid body type of motion (translational and rotational) of a group of nodes (for example, initial velocity for rollover simulation of a vehicle).
2. The initial nodal velocity is calculated as:(1)
$v\left(M\right)={V}^{t}+{V}^{r}\frac{U}{‖U‖}\wedge OM$
Where,
$U$
Vector defining the rotation axis.
$O$
Center of the local coordinate system
$M$
Nodal point
${V}^{r}$
Rotation velocity
${V}^{t}$
Vector of translational velocity
3. This option cannot be used when /INIVEL/TRA or /INIVEL/ROT is applied on the same node.