To display the velocity vectors, perform the following steps.

Select the Vector option under the Insert menu.

Insert → Vector

This displays the Insert Vector dialog box.

Click OK in the Insert Vector dialog box.

In the Geometry tab of the Details of Vector 1 window, click the Location editor button ( ) to the right of the Locations drop-down list. Then select SD_1_surf and SD_2_surf in the Location Selector dialog box, and click OK.

Click Apply.

In the Outline tab, deselect Pressure under User Locations and Plots and deselect Text 1 under Default Transform.

Figure 4.46: Velocity Vectors with Rotation

The velocity vectors take all components of the velocity into account. Along the screw tip, the rotational component is important, leading to rather long vectors that are not in the plane. After the die exit, a rearrangement of the velocity field takes place: the flow slows down along the axis of symmetry and accelerate on the outside. This makes the particles to go towards the free surface, creating the swelling.

Click the rotate button in the toolbar (Figure 4.47: The Rotate Button in the Graphics Toolbar) and rotate the view around the axis using the left mouse button to see the vectors that point out of the plane around the screw tip as shown in Figure 4.48: Velocity Vectors Pointing Out of the Computation Plane.

Figure 4.47: The Rotate Button in the Graphics Toolbar

Figure 4.48: Velocity Vectors Pointing Out of the Computation Plane