A streamline traces the path tangent to a nodal vector field, and a stream is a set of streamlines that enable you to visualize data emanating from a particular location in a vector field. Figure 74–1 shows a sample stream of 12 streamlines displaying velocity data in a fluid flow analysis.

You can create streams by first defining a rake, which is a line segment with a series of points specified along its length that control the locations where Abaqus/CAE displays streamlines for a fluid flow analysis. Rakes are placed into an area of interest in the fluid flow; when you create and display the stream in the viewport, Abaqus/CAE displays a number of streamlines that corresponds to the number of points on the rake. Streamlines are evenly spaced along the rake, except for rakes defined using nontrivial path definitions; for more information about stream rake definition, see “Creating a stream,” Section 74.2.

The streamline shape is driven by the currently selected stream variable, which is usually velocity or vorticity. To change the current stream variable, see “Selecting the stream field output variable,” Section 42.5.7. The streamline color is driven by the currently selected primary variable. For more information on customizing streamline color options, see “Customizing stream colors,” Section 74.4.1.

You must define separate stream rakes for each part instance for which you want to display flow data. Abaqus/CAE computes stream data for individual part instances only and does not display streamlines across separate part instances.