General

General

Is it possible to use the Fluent Adjoint solver to get the optimum for 2 or more different flow conditions?

    • FAQFAQ
      Participant

      Yes, it’s possible. But there is some effort involved when doing it manually. (Note that this will be a full feature in Fluent 2019 R3 for the optimizer.) In the current version, you can use the Shape Optimization ACT which is available for free from the ANSYS store. If you write your own scripts, or want to do it manually, follow these steps: 1. Calculate the flow for the first flow condition 2. Calculate the adjoint for the first observable 3. Export the sensitivity field from the Design Tool 4. Calculate the adjoint for the next observable 5. Export the sensitivity field from the Design Tool 6. Calculate the flow for the second flow condition 7. Repeat steps 2-5 above 8. Read all the sensitivity fields in the Design Tool 9. Set the objectives for the different fields 10. Calculate the design change This can be scripted easily but it’s heavy on computational time. Note that there are two steps that require special attention: 1. The sensitivity fields can be exported from Objectives > Manage Data in the Design Tool. In older versions the export was on the Region tab but reading on the Objectives tab. There were issues in the past when sensitivity files could not be found when Fluent was in parallel mode. It is therefore recommended to delete the references to the sensitivity files on the Objectives tab after the design change. 2. There are two different ways to define the weighting of the different sensitivity fields. If all the objectives are set to “Decrease Value” or “Increase Value”, the weighting can be defined explicitly. For an objective of the type “Target Change In Value” the weighting is done implicitly. It is possible to mix both types but this is best avoided.