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*ACOUSTIC FLOW VELOCITY
Specify flow velocities as a predefined field for acoustic elements.

This option is used to specify the fluid flow velocity of node sets or individual nodes for acoustic analysis. This option defines an underlying flow, about which the acoustic analysis is a linear perturbation.

Product: Abaqus/Standard  

Type: History data

Level: Step

Reference:

Required, mutually exclusive parameters: 

ROTATION

Include this parameter to define a flow velocity field due to a rigid body rotation about an axis.

TRANSLATION

Include this parameter to give the x-, y-, and z-components of translational flow velocity in the global coordinate system or in the local coordinate system if *TRANSFORM was used at these nodes. Translational flow velocity is the default.

Optional parameter:

AMPLITUDE

Set this parameter equal to the name of the amplitude curve (defined in the *AMPLITUDE option) that gives the time variation of the flow velocity throughout the step (“Amplitude curves,” Section 34.1.2 of the Abaqus Analysis User's Guide).

If this parameter is omitted, the default is a STEP function.

Data lines to define translational flow velocity (TRANSLATION): 

First line:

  1. Node set label or node number.

  2. First translational component of flow velocity prescribed (only degrees of freedom 1, 2, or 3 can be entered). See “Conventions,” Section 1.2.2 of the Abaqus Analysis User's Guide, for a definition of the numbering of degrees of freedom in Abaqus.

  3. Last translational component of flow velocity prescribed (only degrees of freedom 1, 2, or 3 can be entered). This field can be left blank if flow velocity for only one component is being prescribed.

  4. Magnitude of the translational displacement or velocity. This magnitude will be modified by the *AMPLITUDE specification if the AMPLITUDE parameter is used.

Repeat this data line as often as necessary to define translational flow velocity for different nodes and degrees of freedom.

Data lines to define rotational flow velocity (ROTATION): 

First line:

  1. Node set label or node number.

  2. Magnitude of the rotation (in radians) or rotational velocity (in radians/time). This magnitude will be modified by the *AMPLITUDE specification if the AMPLITUDE parameter is used. The rotation is about the axis defined from point to point , where the coordinates of and are given next. In steady-state transport analysis the position and orientation of the rotation axis are applied at the beginning of the step and remain fixed during the step.

  3. Global x-component of point on the axis of rotation.

  4. Global y-component of point on the axis of rotation.

    5. The following data are required only for three-dimensional cases:

  5. Global z-component of point on the axis of rotation.

  6. Global x-component of point on the axis of rotation.

  7. Global y-component of point on the axis of rotation.

  8. Global z-component of point on the axis of rotation.

Repeat this data line as often as necessary to define rotational flow velocity for different nodes.