OS-T: 1610 Thermal Fluid-Structure Interaction Analysis on a Manifold

The purpose of this tutorial is to demonstrate how to carry out a Thermal Fluid-Structure Interaction analysis on an engine exhaust manifold with conjugate heat transfer and structural deformation.

Before you begin, copy the file(s) used in this tutorial to your working directory.
This example is an engine exhaust manifold with conjugate heat transfer and structural deformation. The structure is gray cast iron, initially at 300 K. The manifold outer surface has a convective heat transfer coefficient of h = 6 W/m2 K at 300 K. The four inlets to the manifold are held at 500 K with air as the fluid at 5 m/s. AcuSolve passes heat fluxes to OptiStruct. OptiStruct passes the temperatures to AcuSolve.
Note: This tutorial is limited to study fluid and thermal domain only.
The AcuSolve Fluid model (FSI_AS_MANIFOLD.inp) and OptiStruct Structural beam model (FSI_OS_MANIFOLD.hm) files are in the TFSI_models.zip file. Refer to Access the Model Files.
Figure 1. Fluid Structural Model

os_1610_model

os_1610_model2

Launch HyperMesh and Set the OptiStruct User Profile

  1. Launch HyperMesh.
    The User Profile dialog opens.
  2. Select OptiStruct and click OK.
    This loads the user profile. It includes the appropriate template, macro menu, and import reader, paring down the functionality of HyperMesh to what is relevant for generating models for OptiStruct.

Import the Model

  1. Click File > Import > Solver Deck.
    An Import tab is added to your tab menu.
  2. For the File type, select OptiStruct.
  3. Select the Files icon files_panel.
    A Select OptiStruct file browser opens.
  4. Select the FSI_OS_MANIFOLD.hm file you saved to your working directory.
  5. Click Open.
  6. Click Import, then click Close to close the Import tab.

Set Up the Model

Create Set Segment

  1. In the Model Browser, right-click and select Create > Set Segment from the context menu.
  2. For Name, enter FSI_Interaction_Surf.
  3. Click Color and select a color from the color palette.
  4. For Card Image, select SURF from the drop-down menu.
  5. Click on the Elements option and pick all the internal faces.
    Tip: To pick all the elements in the internal face, use the brake angle of 30 degrees.
    Figure 2.

    os_1610_contact_surf
  6. Click add to add the faces to the set segments.
  7. Click return to exit from this panel.

Define Fluid-Structure Interaction Parameters

  1. In the Model Browser, right-click and select Create > Load Collector.
    A default load collector template displays in the Entity Editor.
  2. For Name, enter FSI100.
  3. Click Color and select a color from the color palette.
  4. For Card Image, select FSI from the drop-down menu.
  5. Under ELSET, for SURFID, select FSI_Interaction_Surf.
  6. Input the values, as shown in Figure 3.
    See NLPARM Bulk Data Entry for more information.
    Figure 3.


Define Output Control Parameters

  1. From the Analysis page, select control cards.
  2. Click GLOBAL_OUTPUT_REQUEST.
  3. For THERMAL and FLUX, set Option to Yes.
  4. Click return twice to go to the main menu.

Create Transient Heat Transfer Analysis Subcase

  1. In the Model Browser, right-click and select Create > Load Step from the context menu.
  2. For Name, enter TFSI.
  3. Click Color and select a color from the color palette.
  4. For Analysis type, select Heat Transfer (transient).
  5. Input/Select the Load Collector.
    Figure 4.

    os_1610_load_collector

Submit the Job

  1. From the Analysis page, click the OptiStruct panel.
    Figure 5. Accessing the OptiStruct Panel

    OS_1000_13_17
  2. Click save as.
  3. In the Save As dialog, specify location to write the OptiStruct model file and enter FSI_OS_MANIFOLD for filename.
    For OptiStruct input decks, .fem is the recommended extension.
  4. Click Save.
    The input file field displays the filename and location specified in the Save As dialog.
  5. Set the export options toggle to all.
  6. Set the run options toggle to analysis.
  7. Set the memory options toggle to memory default.
  8. Click OptiStruct to launch the OptiStruct job.
If the job is successful, new results files should be in the directory where the FSI_OS_MANIFOLD.fem was written. The FSI_OS_MANIFOLD.out file is a good place to look for error messages that could help debug the input deck if any errors are present.

Submit the AcuSolve Job

  1. Open the AcuSolve input file (FSI_AS_MANIFOLD.inp) in a text editor.
  2. Change the socket_host parameter in the EXTERNAL_CODE block to your machines hostname and save the file.
    Figure 6.

    os_1600_acusolve_command
  3. Open the AcuSolve Cmd Prompt application.
  4. Enter the folder location for the .inp file.
  5. Enter the command: acuRun -pb FSI_AS_MANIFOLD -np 8.
    Note: Use the command: <cd <file location> And press Enter to navigate to the respective folder.
    Figure 7.


If the job is successful, you will see new results files in the directory where HyperMeshwas invoked. The FSI_OS_MANIFOLD.out file is where you will find error messages that will help you debug your input deck, if any errors are present.
The default files that will be written to your directory are:
cci.txt
Contains information pertaining to model progression. Logs regarding connection establishment, initial external code handshake and subsequent time step data in conjunction with exchange/stagger.
FSI_OS_MANIFOLD.html
HTML report of the analysis, giving a summary of the problem formulation and the analysis results.
FSI_OS_MANIFOLD.out
ASCII based output file of the model check run before the simulation begins and gives some basic information on the results of the run.
FSI_OS_MANIFOLD.stat
Summary of analysis process, providing CPU information for each step during the process.
FSI_OS_MANIFOLD.h3d
HyperView compressed binary results file.

View the Results

Using HyperView, plot the Element Fluxes (Mag) at 100 s.
Figure 8.