ANSYS is commonly used to test wing models and other aerodynamic structures. This short ANSYS tutorial will look into the post-processing of the models after the Fluent is setup.

Table of Contents (click for easy navigation)

1. Setting up ANSYS Fluent Workflow
2. Starting CFD Post
3. GUI of ANSYS CFD-Post
4. CFD Post General Workflow
5. Setting and working with Locations
6. Types of Locations
7. Adding graphics objects
8. Making charts in CFD-Post
9. Other useful features and tools
10. Typical keyframe animation procedure

Setting up ANSYS Fluent Workflow

Setting up the ANSYS Fluent workflow takes a series of different steps. To see how to make the Fluent workflow in ANSYS, have a look into the Fluent tutorial that we have uploaded recently. It covers all the sectors of on how to create the ANSYS Fluent workflow and go about the aerodynamic testing of an object. After the ANSYS Fluent setup is completed, the user can move onto CFD-Post to carry out the visual processing of the object to be tested.

Please note that the CFD-Post can also be used along with ANSYS CFX. The working principles of CFD-Post in ANSYS CFX are same as that in ANSYS Fluent. 

Starting CFD Post

This CFD-Post ANSYS tutorial consists of three different methods of opening CFD-Post after the ANSYS Fluent/CFX is all set-up, CFD-post can be opened by double-right-clicking the ‘Results’ section at the end of the workflow or by left-clicking and edit as demonstrated in the image below;

Another method to open CFD-Post is to create a standalone CFD-Post Session and link it with your fluid flow simulation. Drag and drop session is usually used if your fluid simulation was created in a standalone session.

ANSYS Fluent connected with CFD-Post

Another method of opening your CFD-Post is by your start menu or command line. Go to; Start>All programs>ANSYS 19.2>CFX. Once the CFX standalone version opens, you can use it to open your CFD post as well.

GUI of ANSYS CFD Post

After the CFD-Post starts up, you find the following window;

The opening window of CFD-Post has the outline and other various tabs in the top-left section of the window. This area is also the model tree for all the setups and post-processing tools. The different views can also be selected and used interchangeably.

CFD Post General Workflow

First, the user has to prepare the locations on which the data will be extracted from or the required plots.

The model above is a 2D cross-section of a water tank being tested for the fluid flow once the water starts coming in it.

After the locations are being set, the variables and expressions are being set into the system to extract the data. It must be noted that the setting of the variables and expressions can be done via code input or by selecting the commands from the fluent toolbar. After all the variables and expressions are set, the user can generate qualitative and/or quantitative data at the locations. The reports for the results can then be generated in CFD-Post.

Setting and working with Locations

This ANSYS tutorial also covers the details on setting the locations in the CFD-Post and work on it. To create the locations, go to the insert menu or directly click ‘locations’ from the toolbar. After the locations are created, they will appear as entries in the outline tree.

For the creation of location, the domain, subdomain, mesh regions and boundary are also available. The mesh regions and boundaries can be edited and coloured by any variable. Mesh regions allow the users to access all available 2D/3D interior and exterior regions from the mesh.

Types of Locations

There are several different types of locations, and all are covered in this ANSYS tutorial. All the different locations allow users with more power in their hands to test their product at all testing points. The types of locations and their descriptions are as follows;

Planes

The planes for locations are XY plane, YZ plane, ZX plane, point and normal etc. The location can be bounded via solution domain(s).

Point

Another location type is the ‘point’. By using points, the user can use XYZ coordinates to select the location. The variable maximum and minimum number can also be used to locate where the highest and lowest values occur.

Point Cloud

Point cloud allows the users to create multiple points and help users set up the locations. The point cloud function is also used to create seeds to create vectors, streamlines and more.

Lines

Lines, as the name suggests, helps the users to create lines between two points and carry out the post-processing. Lines are commonly used as the basis for a graph plotting.

Polylines

Polylines are used in the creation of charts, extract a line from a contour plot, read points from a file and use the line of intersection.

Volume

Volumes allow the users to select a 3D surface and carry out the analysis using isovolumic, from surface and node functions.

Adding graphics objects

The graphics to the object can be added to the object via the toolbar or the viewer right-click menus. The most commonly used graphics are the streamlines, contours and vectors. The vector plots can plot any vector variable such as velocity and can also project vectors normal or tangential to the base object. Streamlines allow the users to see the simulated results of the airflow over the object.

Velocity vectors on a propeller

Users can also make the colour map on their testing object to see the effect of air or other variables. The colour map shown below is of a 3D model of a car being tested for pressure distribution on different locations.

Making charts in CFD Post

This ANSYS tutorial also looks into the charts that can be obtained from CFD-Post to better understand the results. In CFD post the users can get a graph to determine the relationship between two variables.

In ANSYS post processing, one of the three types of graphs can be obtained.

• The XY standard graph based on the line locators
• The XY transient or sequence graph which is used to plot an expression, usually time vs any other variable at a point locator. This type of graph is also used to show the transient variation of a variable at a point on the graph.

• Histograms can also be made in ANSYS. They can be based on any location that contains multiple data locations and can easily make plots of a variable divided into the small increments on the X-axis vs the frequency of occurrence on the Y-axis.

Other useful features and tools

ANSYS also has a timestep sector that enables the users to post-process the transient results in the result of the file and then different selector timesteps from the selector. A full animation video for transient solutions can also be made, and the video is savable in multiple different formats.

The quick editor in ANSYS postprocessing provides a quick way to change the primary values connected with each object. The probe allows the users to pick a point from the viewer and probe a variable value at that point.

Typical ANSYS keyframe animation procedure

1. Load the first timestep via the timestamp selector
2. Create necessary plots and positions for your object
3. Create the first keyframe for the animation
4. Load the last timestep
5. If needed, you can change the view and plots
6. Then create the second keyframe
7. Now select the first keyframe and set the needed number of frames
   1. This is the number of frames between the first and the second keyframes. The higher the number of frames, the smoother the animation but would require more computing power
   1. For instance, if you have a total of 50 timesteps, then setting the number of frames to 58 will produce a total of 50 frames (48 plus first and the last).
8. Now set the movie option
9. Rewind the first keyframe and click play.

In ANSYS CFD post-processing, the user can post-process their results in many different methods. This comprehensive ANSYS tutorial has compiled most commonly used post-processing techniques and features in ANSYS CFD Post. If you want to look into more details, visit us back soon.