XFlow DLR F11 High-Lift Simulation


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DLR F11 High-Lift Configuration Analysis

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In this tutorial you will learn how to perform a DLR F11 High-Lift Configuration aerodynamics simulation using XFlow on Rescale.

If you have not done so already, you will need to sign up for a Rescale account.

Required Files

  • HLPW2_Case3_AoA24.xfp
  • HiLiPW-2-Flap.nfb
  • HiLiPW-2-Fuselage.nfb
  • HiLiPW-2-Slat.nfb
  • HiLiPW-2-Wing.nfb
  • SlatFlapTrackFairings.nfb
  • TubesBundle.nfb
  • xflow_numericaldata_extraction_v4.py

Description of the Simulation

Duration: It will take approximately 10 minutes to set up this tutorial, and an additional 2 hours to get the first saved frame of the simulation.

The Simulation: The DLR F11 High-Lift Configuration represents the benchmark geometry used throughout the 2nd AIAA CFD High Lift Prediction Workshop (HiLiftPW-2), a reference benchmark activity for the aeronautical industry aiming at assessing the aerodynamic prediction capabilities of a variety of CFD methods. The geometry is representative for a medium sized wing-body commercial aircraft, the simulation of which is made challenging by the presence of slat tracks, flap track fairings and slat pressure tubes bundles.

Simulation Software: XFlow

Required Files:

File 1 - HLPW2_Case3_AoA24.xfp: the project file containing the setup of the simulation made in XFlow.

File 2-7HiLiPW-2-*.nfb: the geometry files which make up the F11 aircraft model.

File 8xflow_numericaldata_extraction_v4.py: python post-processing script for monitoring aerodynamic coefficients.

License Required: A valid XFlow license is required to run this simulation.

  1. If you have access to an existing XFlow license, contact Rescale support to use your existing license on the Rescale platform.
  2. If you need access to a license, please contact Rescale support to inquire about on-demand licensing.

Accessing Rescale

  1. To begin using Rescale, open any web browser and go to https://platform.rescale.com. Log in using your Rescale account information. Rescale does not require file or software downloads. All components are accessible on Rescale's web-based platform, which enables you to run your analyses from any computer.
  2. Once logged into Rescale, you will see your main dashboard. Click on the +New Job button located in the top left corner of your screen. This will open a new simulation and prompt you to set up your analysis.

Job Setup

  1. Since you can save all your analyses in Rescale, we recommend giving each job a unique name so you can easily identify it later. For example, you could name this simulation "HLPW2_Case3_AoA24". To change the name of your job, click on the pencil next to "Untitled Job" in the upper left corner of the page.

Input File Selection

  1. You can upload the files required to run this analysis by going to Upload from this computer. Upload the 7 input files (the xflow_numericaldata.py will be uploaded in a second stage) which you can get from the tutorial session in Rescale.

At this stage your setup should look like the screenshot below:

Software Selection

  1. Next, navigate to the software settings by clicking on the Software link, just next to the Input icon.

  2. Select the software code you would like to use for your analysis. For this demo, scroll down and click on XFlow.

  3. Make sure the latest XFlow version is selected (2015.96) under Version.

  4. In order to run your input files, an analysis execution command is required. This command is specific to each software code and input file used. Enter the following command in the area designated Command:

    xflow -n 32 HLPW2_Case3_AoA24.xfp
    
  5. Please select a License Option:

    1. If you have access to an existing XFlow license, contact Rescale support to use your existing license on the Rescale platform.
    2. If you need access to a license, please contact Rescale support to inquire about on-demand licensing.

At this stage your setup should look like the screenshot below:

Hardware Selection

  1. Next choose your desired computing configuration. Click on the Hardware Settings link, just below the Software selection icon.
  2. This is where you select the number and type of the cores required to run this analysis. For this tutorial select the Nickel core type and increase the Number of Cores to 512 by specifying that number in the specific text box.
  3. Additionally, it is possible to choose a low priority setting for this case by ticking the Enable Low Priority combo. If available, this option will allow running the job at a reduced price.
  4. Finally, a time limit for the simulation can be set in the Maximum Job Duration combo box. When setting this parameter the job will be killed after the specified duration which could lead to loss of data if the simulation has not reached a timestep correspondent to a frame.

​ At this stage your setup should look like the screenshot below:

Retrieve Results

  1. Next move to Post Processing and upload the file xflow_numericaldata_extraction_v4.py using the Upload from this computer option

  2. Then, type the following command in the Post-processing command window:

    python xflow_numericaldata_extraction_v4.py
    
  3. This additional step allows post-processing the generated numerical data of XFlow and extracting the time history of the aerodynamic coefficients.

At this stage your setup should look like the screenshot below:

Submitting Your Job

  1. After you have completed the Job Setup section, you are ready to execute the analysis. Select Next to review your setup before submission
  2. If the setup is correct the Submit option will be available
  3. If you want to save the job and submit it later you can do so by selecting the Save button

Status

  1. Once the job is submitted the Rescale platform will automatically load the Status tab. At the top of the Status page a summary of the main activities performed is presented. The simulation is first queued and once available computational nodes are identified (the queuing time might vary depending on the priority selected for the job) the simulation inputs are validated to check for any setup incongruity. Finally, the cluster is started and the job execution begins.

  2. While the simulation progresses it is possible to monitor any output log file generated from the Live Tailing area. It is also possible to filter the file by inputting a search term (e.g. log) in the combo box. The main logs generated by XFlow are genbinaries.log which collects the output of the process used by XFlow to create the input files required; generatedomain.log collects the output of the lattice generation process; and finally the xflow.log contains the output messages of the XFlow solver used in the simulation. The latter is particularly important since it provides information on the progress of the XFlow simulation as well as its stability. In fact, it also contains the output of the Stability Parameter at each time-step.

  3. Since the simulation is run entirely in the cloud, feel free to close your browser window or shut down your computer. You can monitor the progress of your job at any time by logging into your Rescale account. You will receive emails notifying you when the status of your job changes, as well as when the job is completed.

Results

  1. The Results tab (click on the correspondent icon on the right side of the window) shows all the results files generated by the simulation. Click Refresh Results to see the newest results produced. Once the analysis is completed it is possible to download any available file individually by selecting the download icon next to its filename. The Download icon at the top right corner of the window provides the option to download a compressed file containing all the selected files (it is possible to select all files clicking on the correspondent Select All icon).

  2. Alternatively, it is possible to retrieve the generated files using the Rescale Transfer Manager (available from the API section in the user settings page).

Post Processing

  1. XFlow allows the post-processing of the available results while the simulation is running on the cluster. In particular an xfdata.hd5 file is generated at a pre-defined frequency, which collects the information on the flow-field at the evaluated time-steps. Therefore, once the result files are downloaded on the local machine the XFlow GUI can be used to open the case and load the data.

  2. Alternatively, it is possible to visualise the results online (without the need to download them in the local PC) through the Rescale Remote Desktop. In order to do so select the Desktops icon from the main toolbar at the top of the window and start a +New Desktop. Select a Windows desktop, provide a name for the desktop and attach XFlow under Software and the results files of the job just run under Jobs.

  1. Once the remote desktop is created it is possible to access the node by selecting the RDP or VNC file from the Node Access page. This will download a setup file to the local machine with the information on how to connect to the remote desktop by using Windows Remote Desktop or Virtual Network Computing system respectively.

  2. Independently on the way the post-processing task is performed (locally or in the cloud) the results of the simulation can be visualised in XFlow as shown in the snapshot below.

This concludes the tutorial on the DLR F11 High-Lift Simulation: congratulations on finishing your first tutorial on distributed simulation with XFlow!