Streamlines are a fine tool for studying the characteristics of air flow. They represent a composition of curves that are tangent to the velocity vector (see above), showing the direction in which a massless fluid element will travel at any point in time (see the explanation at Nasa).
The colors visualize the speed of the particles moving through the wind tunnel. The associated velocities are explained in the panel.
For a visualization of the air flow, activate the "Streamlines Animation" in the panel or on the "Results" menu. You can then watch the fluid particles flowing around the model and examine their speeds and directions.
The graphical settings of the streamlines are controlled in a separate section of the panel. You can access it by clicking Streamlines Settings in the panel or on the "Options menu," pointing to "Streamlines."
Control Points Source
The streamlines refer to control points that are created automatically. You can modify the number of points with the slider.
By default, the control points are located within a 3D Box. It is possible to select a different type of source from the list (see the image to the left), but these options are only relevant for specific evaluations.
When the "Show Manipulator" option is enabled, you can change the size and location of the 3D box graphically in the work window. The functions of the arrows correspond to those for modifying the wind tunnel (see Chapter Wind Tunnel). Click
to transfer the new settings.
Particle Animation
Use the "Animation" option to switch the display of the animated view of the streamlines in the work window on or off.
By default, the flow of the particles is displayed as Lines. When you select the "Particles" option from the list, you can examine the direction and speed of the particles around the model.
To modify the settings of the animated streamlines, click the
button. Alternatively, open the "Options" menu, point to "Streamlines," and select "Streamlines Options." The following dialog box is opened.
Streamlines
The "Display streamlines when animating movement of particles" option controls whether the lines are shown when the "Particle" type of animation has been selected (see above). Furthermore, it is possible to increase the Line thickness of the streamlines display. The "Calculation" of streamlines is effectuated both "Downstream" and "Upstream" by default. The former option enables you, for example, to visualise the effects of drag, the latter to display lift in detail.
Animation of Particles and Flowlines
In this section of the dialog box, you can control the "Count" (number), "Size" (thickness), "Length," or "Speed" of the particles and streamlines utilized for the animated display. Use the slider to increase or reduce the individual parameters.
Click
to review modified settings in the animated view without closing the dialog box.