Solid Fluent Coupling

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  • Last Post 10 March 2019
Bibek Poudel posted this 04 March 2019

Hi all, 

I am trying to get the normal and shear stress in the wall where there is contact of fluids. So, what I did was did a transient simulation in fluent and imported the pressure load into static structural simulation and compute the shear and normal stresses. The problem where I faced was when I tried to solve static structural simulation, in the analysis setting, it asks me the simulation end time. And when I change the time, I get the different results every time. So here is my query: in the static structural simulation, should the time matter? Shouldn't it be the steady state result? Why does it ask me the step end time and why does my result change every time I change that value? Can't I couple Transient Fluent Simulation with static structural simulation? I am not using system coupling tab though. I am using like this: 

Thank you,
Bibek

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Ryan O'Connor posted this 06 March 2019

Hi Bibek,

There are a few issues in your questions, let me break it down and address the questions below:

 

1) How to get normal and shear stress from transient Fluent into Static Structural (Mechanical): The default Interpolation Type (Mechanical-Based Mapping) only transfers the normal pressure. To instead transfer the stress vector (which includes normal and tangential components), edit the Imported Load in Mechanical > in the details view set the Interpolation Type = CFD Results Interpolator. For the Imported Pressure Object, in the data view you must specify the Source Time. Set this as desired.

 

2) Static Structural solution changes based on the Step End Time: The Step End Time should have no impact on the final solution. Take a look at the out file for you various cases to see if there are any warning or error messages that might explain the difference in solutions. If there's nothing useful there, I suspect it's a Mechanical issue that you're facing, not an issue with the imported load. It may be worthwhile to isolate this issue by replacing the imported load with a representative pressure load and see whether you're still having the same problems.

 

Regards,

Ryan

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Bibek Poudel posted this 10 March 2019

Hi Ryan, Thanks for the reply. Yes, I tried using your advice by replacing the imported load with another random pressure load initially. With that, the solution didn't change with time but again, when I used the imported load, there is one result when I use the step time 1 second and another result when I used the step end time 10 s. But interesting thing is after 10 s, when I used the step end time 20 s or 100 s, the result matched with result of 10 s, so why is the result with 1 s only different? Can you provide me any insight in this? 

Thanks, 
Bibek

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