29.6.4 Modifying Iso-Values

One convenient feature that you can use to generate effective animations is the ability to generate surfaces with intermediate values between two isosurfaces with different isovalues. If the surfaces have contours, vectors, or pathlines displayed on them, ANSYS FLUENT will generate and display contours, vectors, or pathlines on the intermediate surfaces that it creates.

Steps for Modifying Iso-Values

You can modify an isosurface's isovalue directly by selecting it in the Scene Description dialog box's Names list or indirectly by selecting an object displayed on the isosurface. Then click the Iso-Value... button to open the Iso-Value dialog box (Figure  29.6.5) for the selected object. Note that this button is available only if the geometric object selected in the Names list is an isosurface or a object on an isosurface (contour on an isosurface, for example); otherwise it is grayed out.

Figure 29.6.5: The Iso-Value Dialog Box

In the Iso-Value dialog box, set the new isovalue in the Value field, and click Apply. Contours, vectors, or pathlines that were displayed on the original isosurface will be displayed for the new isovalue.

An Example of Iso-Value Modification for an Animation

The ability to generate intermediate surfaces with data displayed on them is especially convenient if you want to create an animation that shows data on successive slices of the problem domain. For example, if you have solved the flow through a pipe junction and you want to create an animation that moves through one of the pipes (along the $y$ axis) and displays pressure contours on several cross-sections, you can use the following procedure:

1.   Generate a surface of constant $y$ coordinate (such as the $y$ coordinate at the pipe inlet) using the Iso-Surface dialog box.

2.   Use the Contours dialog box to generate contours of static pressure on this isosurface and manipulate the graphics display to the desired view.

3.   Open the Animate dialog box and create key frame 1.

4.   In the Scene Description dialog box, select the contour in the Names list and click the Iso-Value... button to open the Iso-Value dialog box.

5.   Change the value of the isovalue to the $y$ coordinate at the other end of the pipe, and click Apply. You will see the contours of static pressure at the new $y$ coordinate.

6.   Set key frame 10 in the Animate dialog box.

7.   Play back the animation.

When you play back the animation, ANSYS FLUENT will create the intermediate frames showing contours of static pressure on the slices between the two ends of the pipe. Ten slices will be shown in succession, all with contours displayed on them.

Using the Sweep Surface dialog box to animate the display of contours or vectors on a surface that sweeps through the domain may be more convenient than the procedure described above. See Section  29.1.5 for details.