Step 10: Show the Vortex Structure

CFD-Post displays vortex core regions to enable you to better understand the processes in your simulation. In this example you will look at the helicity method for vortex cores, but in your own work you would use the vortex core method that you find most instructive.

1.   In the Outline tree view:

(a)   Under User Locations and Plots, clear the check box for Wireframe.

(b)   Under Cases / elbow1 / fluid, select the check box for wall.

(c)   Double-click on wall to edit its properties. On the Render tab, set Transparency to 0.75 and click Apply.

This makes the pipe easy to see while also making it possible to see objects inside the pipe.

2.   From the menu bar, select Insert/Location/Vortex Core Region and click OK to accept the default name.

3.   In the Details view for Vortex Core Region 1 on the Geometry tab, set Method to Absolute Helicity and Level to .01. On the Render tab, set Transparency to 0.2. Click Apply.

The absolute helicity vortex that is displayed is created by a mixture of effects from the walls, the curve in the main pipe, and the interaction of the fluids. If you had chosen the vorticity method instead, wall effects would dominate.

4.   On the Color tab, click on the colored bar in the Color field until the bar is green. Click Apply.

This improves the contrast between the vortex region and the blue walls.

5.   Right-click in the 3D Viewer and select Predefined Camera / Isometric View (Y up).

6.   In the Outline tree view, select the check box beside Streamline 1. This shows how the streamlines are affected by the vortex regions.

Figure 1.9: Absolute Helicity Vortex

7.   Clear the check boxes beside wall, Streamline 1, and Vortex Core Region 1. Select the check box beside Wireframe.