Pareto Op Tim Ization Tutorial

8/12/2019 Pareto Op Tim Ization Tutorial

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Pareto Optimization Tutorial 1

Pareto Optimization

Tutorial

This worksheet will show users how to use Optimate to setup a ParetoOptimization study. In this type of study, the user will define the bounds forthe geometry modifications and competing objectives. The MO-SHERPAalgorithm will find the set of designs that are on the Pareto front.

PrerequisitesIn order to complete this tutorial users will need:

Basic understanding of STAR-CCM+

Correctly installed version of Optimate add-on

Correctly installed version of HEEDS Optimate

Process

Starting Optimate1. Start STAR-CCM+

2. Load the pipeMixingBlockage.sim simulation file

3. Start Optimate using the gear icon in the toolbar and select NewProject in the Load Project? dialog box. This action will launch ablank Optimate project and check out a DOEsuite license until theserver is shut down, at which point the license will be released.

Run Mode Tab1. Select the Pareto Optimization mode

Variables Tab1. From the Design Parameters drop down menu, select the depth

parameter. Select the Add button to the right of the drop down box.This will identify the depth of the pipe blockage as a variable thatOptimate can modify.


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2. From the Design Parameters drop down menu, select the TranslateZ parameter. Select the Add button to the right of the drop down box.This will identify the translation of the blockage in the z direction as avariable that Optimate can modify.

3. Confirm that Minimum, Maximum is selected as the definition mode

for the newly created variables4. Select the depth variable. Change the Minimum to 0.04 and the

Maximum to 0.14.

5. Select the TranslateZ variable. Change the Minimum to 0.0 and theMaximum to 0.20.

Outputs Tab1. Select the InletPressure report. Add the report to the record reports by

selecting the Add button to the right of the reports drop down menu.

2. Select the OutletStDev report. Add the report to the record reports byselecting the Add button to the right of the reports drop down menu.

3. Identify the residual plot to be exported after each run by selecting itfrom the plots drop down menu and selecting the Add button to theright of the plots drop down menu.

4. Identify the scene named Velocity to be exported after each run byselecting it from the scenes drop down menu and selecting the Add button to the right of the scene drop down menu.

5. Select the InletPressure report from the list of Recorded Reports . Setthe recording mode to Objective and confirm that the Goal is set tominimize.

6. Select the OutletStDev report from the list of Recorded Reports . Setthe recording mode to Objective and confirm that the Goal is set tominimize.

Assembly Tab1. Set the Simultaneous Jobs to 2 and the number of Cores per

STAR-CCM+ Job to 2. This will require a computer with at least fourcores. If the local machine has more cores, feel free to increase either ofthese settings, but ensure that there are enough tokens available to useduring the run.

2. Set the Number of STAR-CCM+ Runs to 40. This is the minimumnumber of jobs needed to run for a Pareto Optimization problem.

3. Set the Check Frequency to 10. This will tell Optimate to check forcompleted jobs every ten seconds which is reasonable for this small


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analysis.

4. Select the Browse button to the right of the Image Directory field andcreate a new directory named img in the project directory. Select theSelect button to exit the file browser. This will tell Optimate to placeall of the image files in the new directory. Alternatively you can simply

type a relative path into the Image Directory input. If this directorydoesnt exist STAR-CCM+ will create it before exporting the selectedplots and scenes.

5. Ensure that the Save all Simulation and Clear Solution STAR-CCM+ Run Options are selected.

6. Ensure that the default HEEDS Save Option o f All Designs isselected.

7. Select Export Project button. This will prompt you to specify thelocation and name of the Optimate project file being saved. This file canbe used to reload your project in the future.

8. Select the Build Project button. This will create all the files necessaryfor this study and a panel will pop up confirming this has completed.

Run Tab1. Select the Start Local Job button to start the job on the local machine.

This will close the current server and start submitting jobs in thebackground. The output from Optimate will be displayed in theOutput area. STAR-CCM+ servers should be visible in the server list.

2. HEEDS POST can be launched by selecting the Post Process button.

Post-Processing

The results be post-processed in either STAR-CCM+ or HEEDS POST oncethe job is complete.

The exported scenes and plots will be available in the img directory thatwas created.

HEEDS POST

To launch HEEDS POST, select the Post Process button in the Run Tab.HEEDS POST can also be launched externally from the start menu,command prompt or desktop icon.

If HEEDS POST is launched from Optimate, the results file will beautomatically loaded. If launched externally, the following must beperformed to load the results:


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1. Select New from the File Menu

2. Select Import Study from the Home Tab

3. Navigate to the run directory and select the star.hds file

For this analysis, the Pareto front is automatically plotted as OutletStDevvs. Inlet Pressure . To create 2-D relation plots to show the effect of theinputs on the outputs:

1. Select the 2-D Relation icon in the General Plots

2. Select depth as the X-axis parameter

3. Select OutletStDev and InletPressure as Y-axis parameter

4. Select Finish

5. Modify the plot to place the pressure values on a secondary axis. Thiscan be found in the properties menu for the plot as seen below:

6. Repeat the same procedure using TranslateZ as the X-axis parameter

Documents

Pareto Op Tim Ization Tutorial