Prescribed Velocity
The Prescribed Velocity node adds an edge, boundary, domain, or point condition where the translational or rotational velocity is prescribed in one or more directions. The prescribed velocity condition is applicable for Time Dependent and Frequency Domain studies. With this condition it is possible to prescribe a velocity in one direction, leaving the shell free in the other directions.
The Prescribed Velocity node is a constraint, and overrides any other constraint on the same selection.
For details about prescribed velocities and accelerations, see Prescribed Displacements, Velocities, and Accelerations.
Coordinate System Selection
Specify the coordinate system to use for specifying the prescribed velocity. The coordinate system selection is based on the geometric entity level.
Coordinate systems with directions that change with time should not be used. If you choose another, local coordinate system, the acceleration components change accordingly.
Boundaries
From the Coordinate system list select from:
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Global coordinate system (the default)
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Boundary System (a predefined normal-tangential coordinate system)
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Any additional user-defined coordinate system
Edges
From the Coordinate system list select from:
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Local edge system (the default)
For details about the definition of local edge systems, see Local edge system.
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Global coordinate system (the standard global coordinate system).
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Any additional user-defined coordinate system.
Points
From the Coordinate system list select from:
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Global coordinate system (the default)
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Any additional user-defined coordinate system
Depending on the selected coordinate system, the velocity components change accordingly.
Face Defining the local edge system
This setting is used in conjunction with a Local edge system. If the velocity is prescribed for an edge which is shared between boundaries, the edge system can be ambiguous. Select the boundary which should define the edge system. The default is Use face with lowest number.
This section is available only for edges in the Shell interface and is only visible if the selected coordinate system is Local edge system.
Prescribed Velocity
To define a prescribed velocity for each spatial direction (x, y, and z), select one or more of the Prescribed in x direction, Prescribed in y direction, and Prescribed in z direction check boxes. Then enter a value or expression for the prescribed velocity components vx, vy, and vz.
Prescribed Angular Velocity
To define a prescribed angular velocity for each spatial direction (x, y, and z), select one or all of the Prescribed around x direction, Prescribed around y direction, and Prescribed around z direction check boxes and enter a value or expression for in each , , or field.
You can add a Harmonic Perturbation subnode for specifying a harmonic variation of the values of the prescribed velocity in a frequency domain analysis of perturbation type.
Location in User Interface
Context Menus
 Shell>Face Constraints>Prescribed Velocity
 Shell>More Constraints>Prescribed Velocity (Edge)
 Plate>Face Constraints>Prescribed Velocity
 Plate>More Constraints>Prescribed Velocity (Boundary)
Ribbon
Physics tab with Shell selected:
Boundaries>Face Constraints>Prescribed Velocity
Edges>>More Constraints>Prescribed Velocity
Physics tab with Plate selected:
Domains>Face Constraints>Prescribed Velocity
Boundaries>>More Constraints>Prescribed Velocity