ANSYS CFX Batch Tutorials

Multi-Field Run : CFX-Mechanical FSI

This section demonstrates how to run a Fluid Structure Interaction (FSI) between CFX and ANSYS Mechanical on Rescale’s ScaleX platform. The MFX Solver (Multi-Field Run) is used for FSI jobs by CFX.

This example is based on an oscillating plate. A thin plate is anchored to the bottom of a closed cavity filled with fluid (air). An initial pressure of 100 Pa is applied to one side of the thin plate for 0.5 s to distort it. Once this pressure is released, the plate oscillates back and forth to regain its equilibrium, and the surrounding air dampens this oscillation.

To obtain the files needed to follow this tutorial, click on the Job Setup link below and clone the job hosting the file. Next, click Save on the job to have a copy of the files in your Rescale cloud files.

Input Files

The following input files are required for a FSI analysis between CFX and Mechanical :

  • OscillatingPlate.def : CFX Input file
  • OscillatingPlate.inp : ANSYS Mechanical input file

Please refer to ANSYS Documentation for creating these necessary input files.

Rescale Job Setup

After obtaining the necessary ANSYS Fluent files, we will now submit a Basic job on Rescale. For more information on launching a basic job, please refer to the tutorial here.

Input Files

  • On the Rescale platform, click on + New Job on the top left. Name your job and make sure the Job Type is set to Basic.
  • Next, upload the input files (.def and .inp) using either the Use files from cloud storage button if the files are stored on Rescale’s cloud storage or the Upload from this computer button if the files are located on your local workstation.

Software Settings

  • Click Next to move onto the Software Settings section of the setup. Under Select Software, search for ANSYS CFX and click on the software icon.
  • Under the Analysis Options tab, you can select the CFX Version using the Version drop down box. Under Command, type the following command line specific to CFX Multi-Field run :
cfx5solve -def OscillatingPlate.def -ansys-input OscillatingPlate.inp -mfx-run-mode "Start ANSYS and CFX" -par-dist $HOSTLIST
  • The -def flag is followed by the CFX input file (.def) and the -ansys-input flag is followed by the mechanical input files (.inp). The -mfx-run-mode "Start ANSYS and CFX" starts the Multi-Field run by starting both the CFX Solver and the ANSYS Mechanical Solver.
  • Additional arguments can be sent to the ANSYS Mechanical Solver using the -ansys-arguments flag. For Example :
cfx5solve -def OscillatingPlate.def -ansys-input OscillatingPlate.inp -mfx-run-mode "Start ANSYS and CFX" -ansys-argumenst "-np 4" -par-dist $HOSTLIST
  • In the above command line, the -ansys-argumenst "-np 4" tells the ANSYS Mechanical solver to use 4 partitions.
  • Under License Options, select the appropriate license type and fill in all the relevant fields with your license details.

Hardware Settings

  • Under Hardware Settings select the appropriate coretype and the number of cores. For this tutorial, we select Emerald as the coretype and request 8 cores. A summary of your hardware information is available on the right side of the platform page.


  • There are no post-processing settings in this tutorial. Click on the Review icon. Check that the setup is correct by reviewing the Basic Job Summary table. It should look like this:
  • After reviewing your job setup, you can submit the job by clicking on the blue Submit icon on the top right corner and on the Job Summary page.

Job Monitoring

  • After you submit the job, the Status page opens on the platform. Here, you will be able to monitor the job progress in a Gantt chart like format, see a date and time stamped log and live-tail the status and output of your job using the Live-tail window. A guide on Monitoring Status on Rescale is found here.

You can also use Rescale’s Live Tailing feature to view the progress of the run by clicking on the log files generated. For this example, you can click search for the .out file from the search field and view the contents of the file as shown below :

Downloading and Viewing Results on CFD-Post

Once the job is completed, you can either view the results on your local workstation or on a Rescale Desktop. Both methods are presented below:

On your Local Workstation

Note: If you have large output files, it is recommended that Windows users use Rescale Transfer Manager (RTM) to download files faster onto your on-premises workstation. More information about RTM can be found here. Linux or Mac user can use Rescale CLI to download larger output files.

  • Go to the results page of the completed job and select the Download Job icon as shown to download all the result files. If you wish to download only a few specific files, you can select the files and click on Actions > Download selected files. Rescale will zip all the results files.
  • To view the results on CFD-Post, launch the application and click on File > Load Results…. Navigate to the location where you saved the result files and open the .res file to view the results.

On a Rescale Desktop

Once the job is completed, follow these steps to view results on a Rescale Desktop:

Set up a Desktop Session:

  • Under 1. Choose Configuration dropdown, select the hardware for your Desktop Session
  • Under 2. Add Software dropdown, select ANSYS Fluids Desktop. Select the version (For this example, we choose 19.0)
  • Under 3. Jobs dropdown, search for the job you wish to add by typing the name and/or browsing through the list. Click Add to add a job to the Desktop

Once the Desktop session is started, click on the CFX Launcher icon on the desktop and launch CFD-Post.

  • To view the results on CFD-Post, launch the application and click on File > Load Results…. Navigate to Desktop > attached_jobs > [Job_Folder] > run1 and open the .res file to view the results.