How to Setup ANSYS Mechanical Project in Interactive Mode and Solve it in Batch Mode on Nimbix

This article describes the workflow and settings/considerations to convert ANSYS Platform setup to batch mode solver on the Nimbix cloud.

To access the ANSYS Platform on the Nimbix platform, the following steps are required:

1. Select the desired ANSYS Platform release from the Compute dashboard.

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NOTE: If the option is not available in the first-page menu, press on “More” at the bottom of the page as shown in the image below:

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2. A splash window will open. Select the ANSYS Workbench Platform option as shown below:

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3. Cloud set-up screen opens and here you must choose some of your settings by clicking on the Tabs on the top of the window (General, Optional, etc.) one tab at a time.

UNDER GENERAL TAB

1. Under Machine type when you click on the caret on the right, you can select the type of machine you want to run your job on. The decision on machine type selection is based on the size and complexity of your model and cost associated with the machine type (some machines will have higher RAM, others will only run the job on single CPU, others will have a GPU and therefore higher cost, etc).

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NOTE: When running interactive based applications, you’ll find that selecting an NC9 or any NC* machine types should offer significant visual performance over not selecting an NC machine type. By selecting an NC machine, this places a GPU on your head-node and offers better visual performance. Another thing to keep in mind is that when running interactively you can use a web browser, or in some cases for large models or you might consider using RealVNC.

2. Select the number of cores. The machine type you selected in the previous step, will dictate the increment in the number of cores that you can choose/select. For a very simple and small model, you can leave default selection, which in this case would be “16” or move the scroll bar to the desired number of cores or simply type over “16” the number of cores you wish to run your job on (we left it to default in this case):

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NOTE: Do not confuse the number of cores with the number of nodes (nodes represent the number of increment of cores that you selected. In the example above, 1 node represents 16 cores, 2 nodes correspond to 32 cores).

UNDER OPTIONAL TAB

1. Assign a JOB LABEL (give a name that will help you keep track on your running jobs. For example, Interactive2Batch_Project):

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2. Leave blank the wall time limit and the IP address. The Window size needs to be kept as default.  Do not enter an Elastic License Server ID unless you use an elastic license on a designated server. 

UNDER STORAGE TAB

Select vault type: Default vault is “drop.jarvice.com”

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The “drop.jarvice.com” vault is recommended for small to medium size jobs, such as Icepak projects, simple linear Mechanical Analysis projects, some HFSS and simple Fluent projects (not multi-phase). For any complex and computationally heavy jobs, and where partitioning the job over the number of cores becomes challenging, the PREMIUM vault is strongly recommended. The PREMIUM vault can be found under the drop down menu under “Select Vault” tab (NOTE: requires a subscription and extra monthly payment to have access to PREMIUM vault). 

Before submitting your job for running, you can preview your settings under the PREVIEW SUBMISSION tab.

Start your Nimbix job by clicking on the SUBMIT button.

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After ANSYS Workbench Platform has been successfully launched, you should be able to see the ANSYS Workbench in the preview and can access the window by clicking on it (you can see details on the number of nodes, some information regarding memory, etc):

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After clicking “OK” on ANSYS feedback survey participation window, you are inside the Ansys Workbench environment:

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ANSYS Workbench is a software environment for performing structural, thermal, and electromagnetic analyses. You can also perform tasks such as geometry creation and optimization, attaching an imported CAD geometry, setting up the finite element model, solving, and reviewing results. 

Be sure to save this project by clicking on “File” to “Save As” to  MyInteractive2Batch (any name you wish to give; the name here is your file name, not to be confused with the job name which is just a bookkeeping name of the project that runs, especially when you run multiple projects at once).

PRE-PROCESSING IN INTERACTIVE MODE

BUILD YOUR FINITE ELEMENT MODEL:  Most elaborate ANSYS models contain several linked analyses and other system components such as Design Exploration. In this article, a simple model of a hollow beam, 0.5 m long, and constant rectangular cross-section (0.1mx0.05m with 0.01m wall thickness) under constant pressure (1MPa) will be used as an example.

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NOTE: Complete your model set-up in INTERACTIVE mode (pre-processing, meshing, analysis settings and output controls as needed).

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NOTE: Additional analysis environments can also be added to the active/current ANSYS Mechanical analysis through the “Analysis” option (can be used for Multiphysics platform analysis or pre-load analysis). DO NOT SOLVE YOUR MODEL IN INTERACTIVE MODE!

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WRITE YOUR INPUT FILE (to be used for batch solver):  Click on “Write Input File” in the “Environment” tab:

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NOTE: Some newer ANSYS Mechanical releases (e.g. 2020 R1) customize the displayed toolbar based on the pre-processing step context. In order to write the input file, the user needs to click on the “Static Structural” analysis step to display the “Environment” tab under “Context”.

SAVE THE INPUT FILE: Browse to the desired location and save the input file (click the Save button)

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Save your model and exit!

SOLVING IN BATCH MODE

1. Start ANSYS in batch mode (same version as interactive). In this case, use ANSYS Structures 2020 R1 in batch mode:

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2. Click on the Mechanical (Batch) button from the splash screen.

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3. Choose the number of cores (same process as for the interactive session). Use a machine that matches your needs (computation performance vs. cost balance.

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NOTE: Optional parameter: select either IBM or Intel MPI as desired to match your machine type if desired. Since you are not using the interactive mode, you can use an “N*” machine vs an “NC*” machine.

4. Select the Input File from where you have saved it earlier by clicking the “…” ellipsis and navigate to the corresponding folder where the input file was originally saved:

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5. Navigate to the saved input file in the Select File window (see below an illustration of the browsing interface in NIMBIX):

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6. Provide a job name (optional) and click Submit.

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7. The job will run in the batch mode. Monitor the job run in the Output window for any error messages:

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8. You can also monitor your utilization (to see how much memory is utilized and whether the number of nodes you selected is in fact used). Click on the Detailed Metrics button (see above):

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NOTE: The solver output can be inspected as a text file post-run (usually also sent as an attachment to the e-mail associated with the current user or downloadable from the job history).

9. Perform post-processing operation by opening your project in the Workbench interface as shown below: 

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10. Edit the Model using ANSYS Mechanical to retrieve the results from the batch run in the interactive mode. Select Read Results Files button (located in the Solution tab – under Context). 

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NOTE: Some newer ANSYS Mechanical releases (e.g. 2020 R1) customize the displayed toolbar based on the pre/post-processing step context. In order to read the results file, the user needs to click on the “Solution” analysis step to display the “Solution” tab under “Context”.

11. Navigate to the results folder and select the .rst file (accept the batch unit system or customize as desired). 

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NOTE: By default, ANSYS defers to the installation folder. Navigate to your “data” folder clicking the “Up” button until your “data” folder is displayed or using the caret to navigate to the data folder. The results are saved under the “Job_name.rst” folder (usually in the folder that contains the run date). If you have not named the folder, the results will be saved under “JARVICE.rst” name). It is advisable to name your job when running the batch process to clearly name the results file.

12. Post-process your results using ANSYS Mechanical in an interactive mode:

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NOTE: Once the results are brought into the interactive Mechanical session, the Solution gets the green checkmark signaling the successful reading of the results into the Mechanical GUI.

Below are a few advantages of preprocessing and post-processing in interactive mode and solving in batch mode.

  • Shorter run times in batch mode than interactive mode.
  • Can balance between run time (speed) vs. cost (number of cores).
  • Results from batch mode run are portable (APDL and Workbench).
  • Input files can be modified (using APDL scripting) to include additional APDL commands.
  • An automatic solver shutdown eliminates the need to monitor the run (can run multiple jobs simultaneously).
  • Post-processing can be done using ANSYS Mechanical graphical user interface (convenient and easy to use).
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