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-   -   FSI Fluent -> static structural (https://www.cfd-online.com/Forums/ansys/143074-fsi-fluent-static-structural.html)

zytra October 16, 2014 02:23

FSI Fluent -> static structural
 
Hi
finishing on my project I have a specific problem with the static structural solver after successful CFD from Fluent.

I have a steady state solution to a solid / liquid problem. I am exporting the solid temperature data calculated with CFD into the static structural solver. The fluid body in the static structure solver is suppressed from the problem, only looking at the sold.

The temperature data is correctly added to the solid/mesh.
I add gravity as it's also part of my conditions. And a simple fixed support.

What I want to do is calculate the total deformation of that solid based on the temperatures calculated from CFD.

Everything seems to be working but the results are directly dependent on the "environmental temperature" setting in the static solver. I understand that this setting is needed in many situations, but in my case, I want it ignored. I used Fluent to calculate the solid temperatures and I don't want these temperatures to be affected by an additional condition.

Not sure if you understand what I am trying to do but my questions are:
1. is there a way to deactivate this "environmental temperature"?
2. if not how could I do what I am trying to do?

thanks for any idea/help!

Best,
Steve

danny261083 October 16, 2014 14:59

Hi Steve,

I believe that you are solving a one way FSI problem of transferring thermal loads from Fluent to Ansys Mechanical. You can export a data file of the temperature values using CFD Post and read the same using the external input option in workbench. You can then specify the temperature magnitudes and offsets (deltaT) while setting up the problem. I am not sure whether this approach would address your question.

Regards

zytra October 16, 2014 15:36

Hi Danny

thanks for the response

it's actually exactly what I did and it works - I mean does compute some results.

The only issue that I am having is the "environmental temperature" setting in the Static Structural solver. I can't find a way to disable it.

The reason I don't want it, is that the thermal problem has been solved already and I just want to see the static impact of these thermal constraints (temperature gradient within the solid).

As far as I can tell the static solver uses this additional input to compute new temperature gradients based on this input - which is defeating the purpose of having solve the thermal problem.


Steve

danny261083 October 16, 2014 17:44

Quote:

Originally Posted by zytra (Post 514699)
Hi Danny

thanks for the response

it's actually exactly what I did and it works - I mean does compute some results.

The only issue that I am having is the "environmental temperature" setting in the Static Structural solver. I can't find a way to disable it.

The reason I don't want it, is that the thermal problem has been solved already and I just want to see the static impact of these thermal constraints (temperature gradient within the solid).

As far as I can tell the static solver uses this additional input to compute new temperature gradients based on this input - which is defeating the purpose of having solve the thermal problem.


Steve

Hi Steve,

You could import the thermal loads using the procedure that I outlined previously and check for the temperature distribution on the fluid-solid interface. If it matches with that observed in Fluent, then I believe that the structural solver is not offsetting the values with the ambient temperature (you can refer to the following post http://www.edr.no/blogg/ansys_blogge...tress_analysis). However, if you do observe that the temperatures are being augmented by the environmental temperature, you can go back to your input data file and subtract the ambient temperature value at all the nodes (for the FSI interface).

Regards

zytra October 16, 2014 18:01

Thanks Danny
I've played with the Environmental Temperature input and with a given set of CFD results I could clearly see an impact on the deformation depending on the ambient Values. That's when I decided to export the average temperature of my solid and import it as "environmental temperature" set as input parameter for the static analysis.

Not sure how subtracting (or adding) the ambient to the temperature values of my solid would give me the results I'd expect. Unless I am not understanding what calculations the solver is doing when applying that ambient temperature. But I could try that.

Thanks again

Best,
Steve


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