Fluent post-processing: recording animations

In transient simulation, animation production is a crucial post-processing step. In Fluent, animation output consists of two steps

Step 1: setting up animations

In the Fluent interface, on the outline tree, go to the “solution animations” page to set the animation content.

The "animation definition" interface is shown below.

Some key points of animation definition:

1 Setting the reasonable output frequency of animation frames, the frequency can be based on the time step, iteration count, or physical time

2 Explanation of storage type:

• Recommended type is "HSF file", which is a three-dimension image file format that allows you to modify the viewpoint freely during playback and animation creation
• If you only need to view the instantaneous state without saving the animation, the type can be set to "none"
• The "in memory" option saves the animation directly in memory, but this is usually not recommended because it can cause Fluent to crash due to insufficient memory
• other options are two-dimension picture format, which are not recommend

3 It is suggested to use a relative path for saving, as absolute paths might cause issues if files are moved or relocated

4 If you do not need to view the animation midway, you can skip setting the viewpoint

5 Animation can show one graphic object only, a scene should be created if multiple object need to be shown at the same time

Step 2: Playing the animation and writing the file

The animation output process involves two types of files:

• CXA file: A text file that records the corresponding files for each frame of the animation
• Data files for each frame: These are the files (like the HSF files set in Step 1) corresponding to the animation frames

Both files are essential.

In the Fluent interface, on the outline tree, go to the “palyback” page to playing animation and write file

The playback page shown below.

Using HSF files to save animations allows you to adjust the viewpoint freely during playback. This is not possible with image formats.

Click the “write” button in the interface to output the animation file. After waiting for some time, Fluent will prompt in the command line that the output is complete.

The output video file's format, frame rate, and resolution can all be customized in the "video options" interface.

In the “playback” interface, clicking the “read” button allows you to read an existing CXA file to create an animation without needing to load the model or results data again.

Attetion

• Setting animation content should be done before the calculation starts. If you stop the calculation midway and then set up the animation, the earlier data will not be included (e.g., if a simulation runs for 3 seconds and the animation is set after 2 seconds, the animation will only show the last 1 second, and the first 2 seconds will not be included).
• Adding animations will significantly increase computation time, and the increased time is strongly related to factors such as the number of animations, saving frequency, and complexity.