This article describes the workflow and settings/considerations to run Star-CCM+ CFD software on the Nimbix cloud in batch mode.
To access Star-CCM+ on the Nimbix platform, the following steps are required:
1. Select the desired Star-CCM+ release from the Compute dashboard.
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:
A splash window will open. Select the Simcenter STAR-CCM+ (Batch) option as shown below:
2. The Nimbix 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 better graphics and therefore higher cost, etc).
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 “2” or move the scroll bar to the desired number of cores or simply type over “2” the number of cores you wish to run your job on (we demonstrate 4 cores in this case):
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 2 cores, 2 nodes correspond to 4 cores).
3. Enter the POD license key (need valid license to run Star-CCM+ on NIMBIX). The POD license key in this example is NOT a valid POD license key.
4. Select the desired simulation scenario (pre-processing must be completed using the GUI and saved in your “data/” subfolder) clicking on the ellipsis button next to “Simulation database (.sim)” dialog box:
NOTE (WARNING): Clear the solution if you have previously solved your model with different conditions (to start from scratch). To clear the solution, follow the following steps in Interactive mode: Solution to Clear Solution. STAR CCM will not initialize and restart the solution if your model is already solved. For the purpose of this demo, a flow obstruction is set up using the interactive Star CCM+ (preprocessor).
UNDER OPTIONAL TAB
Assign a JOB LABEL (give a name that will help you keep track on your running jobs. For example, my_STARCCM_batch_Project):
2. Leave blank the wall time limit, Macro file (unless planning on using a macro in batch mode – option available in NIMBIX), and the IP address. The Window size needs to be kept as default.
UNDER STORAGE TAB
Select vault type: Default vault is “Elastic_File”.
The “Elastic_File” 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 number of cores becomes challenging, the Performance_SSD vault is strongly recommended. The Performance_SSD vault can be found in the drop-down under “Select Vault” tab (NOTE: requires subscription and extra monthly payment to have access to Performance_SSD 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:
After Star-CCM+ has been successfully launched in batch mode, you should be able to see the Star-CCM+ run in the preview and can also monitor utilization by clicking on the “Detailed Node Metrics”:
The simulation output (contains valuable information about the problem set-up, cores, residual runs) can be accessed once the run is completed as a text file by down caret in the “Recent” job option:
Save the file by clicking on the “Download Complete output” (yellow) button and open it with any text editor:
POST PROCESS IN INTERACTIVE MODE AS NEEDED
Open Star CCM+ in interactive mode and post-process your results. The results will be stored in a simulation (.sim) file in the current (working) directory next to your original simulation (preprocessed) file. The file name will be the label the initial simulation name concatenated with the number of simulation steps run using the @ character (in our example, we ran the starMy_Star_CCM_Project for 602 steps so the results will be stored in starMy_Star_CCM_Project@00602.sim file:
Post-process as needed (in this example, smoothed velocity contour on the symmetry and internal walls of the problem is plotted and reported):
Velocity magnitude distribution as computed on symmetry planes and internal walls (no-slip).
Should you have any questions on the above steps, please reach out to us at firstname.lastname@example.org.