Transient FSI Heat Exchanger

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  • Last Post 09 July 2018
nds88 posted this 28 May 2018

Hello, I am running my first Transient FSI in AIM which will be based around a heat exchanger. The hot side of the heat exchanger will include a gas that will be increasing in temperature in a non-linear fashion. I have data that these temperatures will be based on, how do I add them in AIM?  (in Mechanical it is a simple excel-like data entry step-loading).


Just for background, the hot side of the heat exchanger is a gas, as mentioned, and the cooling side is a liquid that will be at a constant flow rate. I am looking to see the stress due to thermal loading on the surrounding enclosure. Any advice or reference material that could help clear up these issues? Thanks so much. 

(Edit, the other error I was receiving was able to be cleared.) 

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peteroznewman posted this 28 May 2018

What version of AIM are you running: 18.2 or 19.0?  Are you using a Student license or a Research license?

If you use Winzip or 7-Zip to create a zip file of the folder that has your model and the Excel spreadsheet with the temperature profile, you can attach that zip file to your original post using the Attach button.  The zip file has to be < 120 MB.  If it is larger than that, try clearing the mesh and saving the project. Having your model will make it easy to investigate your question.

nds88 posted this 29 May 2018

I am using the 18.2 AIM Student Version. I have workbench as well but I was having difficulty setting up the solution passing, so I decided to use AIM instead. I was able to get a steady state solution as a rough draft but thats not what I'm looking for. I would attach that .wbpj file but the size is too large even without the mesh (330 mb).  

peteroznewman posted this 29 May 2018

Do you use Gmail?

Large attachments on Gmail are put on Google Drive and a link is created to send as the email content with no attachment.

There are similar tools on other email systems. There are also services like Dropbox for sharing large files.

Please reply with a Google Drive link.

nds88 posted this 29 May 2018

Try this?

peteroznewman posted this 30 May 2018

I downloaded your zip file.  Sadly, I had errors opening that file in AIM 18.2. I'm getting the feeling that it is impossible to move AIM files between computers. I tried the File, Archive method and failed, I have tried the folder zip method and failed.  I might write a post just on this alone.

I recommend you work exclusively in Workbench and forget about AIM.

I looked at your spreadsheet and was curious why the temperature went on a sawtooth profile. That is a weird way to be "increasing in temperature in a non-linear fashion". Do you mind explaining that?

nds88 posted this 30 May 2018

The temperatures are based on thermocouple data from a study. I only sent some of the data because there are about 350 data points and I didnt want to tabulate all of them if this wasnt going to work. How would you recommend establishing the workbench solution path for a transient FSI?

peteroznewman posted this 30 May 2018

Are there two thermocouples?  This looks like data from two thermocouples is interleaved in one data file. Please explain why the temperature is oscillating so wildly between these two extremes.

Put the thermal stress evaluation aside, and also the heat transfer. Start building a model of two fluids flowing through a structure. You have to create the geometry of the solid body that separates the two fluids, and create a solid body for each fluid with named selections for the inlets and outlets. What is the flow rates for each fluid? Get that model working, then later add in the heat transfer in a second version of the model. Finally add in the thermal stress in a third version of the model.

If you created the geometry in SpaceClaim for the AIM model, you can save the SpaceClaim file and use it as input to the Geometry in a Workbench model.

nds88 posted this 30 May 2018

If you would like to PM me to talk more about the model and experiment I would gladly go into more detail, but the original question was really just based around how to use AIM's "time-dependent" option instead of steady state model. I assumed there was a step loading option similar to workbench but it seems like there isnt.

I have already filled the cavities and ran the simulation as a steady state FSI and obtained solutions. I just want to model the temperature change to match the data that I have which is the part that is proving to be more difficult. The steady state solutions are only based on the maximum temperature, a constant. I apologize if my question was not clear.

peteroznewman posted this 30 May 2018

I am not expert at AIM, so I can't help with your original question.

Bode1 posted this 09 July 2018

I'm getting the feeling that it is impossible to move AIM files between computers. I tried the File, Archive method and failed, I have tried the folder zip method and failed.

peteroznewman posted this 09 July 2018

I had a defect in my AIM installation that was preventing opening archives. I later reinstalled AIM and was successful moving AIM files between computers.

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