Learning Forum

[Clifford Omonini]

Please I am trying to use adjoint optimization for mass flux variance. The flux variance is reducing normally but no significant changes is observed after the simulation. I don't know why? Does the bounds have something to do with this?

[DrAmine]

Hello,

according to the first part of your second sentence the variance is reducing. That is a change of your simulation. What other changes are you expecting?

Please explain your question in more detail that we can understand your steps and which part gives unexptected results.

[Clifford Omonini]

I am trying to reduce variance to enhance flow uniformity at the outlet. But when I plot the graph for outlet velocity after the optimization, it is same with the previous one before optimization.

[Clifford Omonini]

 

Also when I try to combine mass flux variance and pressure drop as observables using linear combination, only the variance reduces but pressure loss does not.

 

[DrAmine]

It is hard for us to provide assisstance without looking into to the case and doing some more invetigat work. Moreover as Ansys Employee, we do only provide high level guidnace on this forum.

There is no guarantee that both components of a compound observable improve. If you build a sum, only the (sum)-result must improve. If one of the components of the sum, outweights the other, it is even possible that one improves and the other one gets worse.

The alternative is a multi-objective optimization but due to the stiff nature of the optimization problem, you might not get a useful result at all.

 

We recommend doing a sensitivity analysis to understand in which high-sensitivity regions the observables are in conflict or support each other. That can give you hints why a multi-objective optimization does not work or why compound observables favor one of the components.

 

Good Luck!

[Clifford Omonini]

Thank you for your feed back. 

I want to ask, is it possible for me to send my case so you could take a look?

[DrAmine]

Hi,

no that is not possible.

If you eligible for direct support, please contact your local distributor to get appropriate guidance on this.

[Aras karimi]

Hello Dear DrAmine,

I am optimizing a 3D airfoil using Fluent's adjoint solver. I have two design constraint, one of which is a fixed chord length and the other is a fixed camber line. During optimization, these two conditions must be applied.
I see a number of design conditions from the design conditions tab in Design Tool, but I don't know which one I should use correctly.

I have also read the User Guide of the Adjoint Solver completely but I still don't know which one to use and how to use it.
I spent a few months trying to solve this problem but I didn't succeed.
I hope you can help me how to apply these two design conditions to the geometry. Thankyou

Regards.