Learning Forum

[idenyu8701]

Hi everyone !!

I want to simulate a wing with a flap using fluid-structure interaction (FSI).

My plan is to first use Fluent to obtain the force data on the wing and then import these results into Transient Structural to simulate the structural response of the wing. However, I'm not sure how to set this up. 

Can someone provide some guidance?

 Additionally, should I use one-way or two-way coupling?

Thank you so much !!

[Rahul Mule]

Whether to use one-way or two-way coupling depends on the degree of physical coupling between the fluid and solid solution fields. If fields are strongly coupled you can use two-way coupling otherwise one-way.

For one-way FSI you can import fluent results in MAPDL by direct schematic connection between the Fluent solution cell to setup cell of MAPDL. Please refer user guide for more information: Using Imported Loads for One-Way FSI (ansys.com)

Also, refer following tutorials to know the setup of two-way FSI coupling:

Analyzing FSI with ANSYS Fluent and Mechanical - Part I (youtube.com)

Analyzing FSI with ANSYS Fluent and Mechanical - Part II (youtube.com)

Reed Valve FSI Co-Simulation with Partial Setup Export from Workbench (Fluent-Mechanical) (ansys.com)

Hope this helps!

 

[idenyu8701]

Hi Rahul!
Thank you for your response and for helping me a lot! However, I've encountered another small issue.

When I converted the results in Fluent to an MPDL file and imported it into Transient Structural under "Import Pressure,"I encountered an issue with the CFD Surface.

I am unable to make any settings for the CFD Surface. Is there any step I might have missed?

Could you give me some suggestions to help me resolve the difficulties I'm encountering when importing pressure into Transient Structural?

Thank you so much !

[Rahul Mule]

Whether your Fluent results are solved in WB or in standalone Fluent?

[idenyu8701]

Sorry I'm not sure about what you mean.

but I use WB to do my work, and I have a little question because I'm not really sure.

I currently have a question: if I don't use the system coupling, it is a one-way coupling.

If I use the system coupling to set up the subsequent solution, will it be considered a two-way coupling?

Thank you very much!

[Rahul Mule]

Yes, if you want to solve it as two-way coupling, use system coupling to connect Fluent and MAPDL. 

You can also run one-way coupling with system coupling by deleting data transfer from MAPDL to Fluent. 

[idenyu8701]

Thank you so much for your reply. I finally understand.

I have successfully exported the Fluent data to Transient Structural, but I am not sure if the imported file includes all the time steps (0~400) or only one time step (400).

 After solving, my object is not fully inflated as expected.

thank you so much!!

[Rahul Mule]

You can set Source Time to “All” to fill entire time history automatically. Ensure that you have the Fluent "data files" saved at required steps to load it into MAPDL. 

[idenyu8701]

Thank you for your suggestion. I made the changes accordingly, but encountered two errors after solving the results:

1. Data Import Error: An error occurred while importing the data. Additional information may be available in the Load Transfer Summary.
   I followed this process to import the data: (file > export > solution data > MAPDL file type > choose fluid-solid > write). Is there something wrong with this process?
2. Target Mesh Import Issue: No data was imported on the target mesh. The Imported Data Transfer Summary shows that the number of nodes mapped count is zero.
    Could this error be due to selecting the wrong CFD surface or Scope's Geometry?
   Could you please help me identify the possible causes and solutions for these errors? Thank you very much!

[Rahul Mule]

To import CFD data to MAPDL follow the procedure: 

1. Connect your Fluent solution cell to the MAPDL setup cell.

1. Double-click the Setup cell to open Mechanical. By default, an Imported Load folder is added under the Environment folder.

Target mesh import issue could be due to the incorrect selection of the CFD surface/scope's geometry. Mapping is required to pass data from a source mesh to a target mesh.

Make sure FSI interfaces on fluid and solid sides overlap. Ideally, both fluid is extracted from the solid, i.e. the same source geometry.

[idenyu8701]

Sorry, I can't successfully see the photo you uploaded. Could you please upload it again?
Thank you very much!

[Rahul Mule]

To import CFD data to MAPDL follow the procedure: 

1. Connect your Fluent solution cell to the MAPDL setup cell.

1. Double-click the Setup cell to open Mechanical. By default, an Imported Load folder is added under the Environment folder.

Target mesh import issue could be due to the incorrect selection of the CFD surface/scope's geometry. Mapping is required to pass data from a source mesh to a target mesh.

Make sure FSI interfaces on fluid and solid sides overlap. Ideally, both fluid is extracted from the solid, i.e. the same source geometry.

****************************************************************************************
This procedure is also given in user manual at: Using Imported Loads for One-Way FSI (ansys.com)

[idenyu8701]

Thank you very much for your help in successfully setting up the one-way fluid-structure interaction!

Now, I need to move towards the goal of two-way fluid-structure interaction, but I am currently encountering three issues:

1. Is it true that one-way FSI cannot integrate the changes in the fluid and solid into a complete animation, and only two-way FSI can create a complete animation of fluid-structure interaction?
2. I have tried adding the System Coupling module, but I do not quite understand the settings for the Data Transfer part. Could you provide me with some suggestions?
3. Regarding Fluent, Transient Structural, and System Coupling, all three modules have their own Step Control settings. My question is, do the Step Control settings of these three modules need to be identical?
   

   I look forward to your reply. Thank you very much.

    

[Rahul Mule]

Refer to the following tutorials to learn the setup of two-way FSI coupling:

Analyzing FSI with ANSYS Fluent and Mechanical - Part I (youtube.com)

Analyzing FSI with ANSYS Fluent and Mechanical - Part II (youtube.com)

Reed Valve FSI Co-Simulation with Partial Setup Export from Workbench (Fluent-Mechanical) (ansys.com)

This should answer above stated questions. 

[idenyu8701]

Thanks for your help!