AFV-T: 3000 Transient Data

This tutorial shows you how to work with transient data. It also shows how to create streaklines to visualize transient flow patterns. An outline is presented for setting up rakes which can be used for subsequent work with other datasets.

Prior to running this tutorial, copy the expanded vortex_shedding directory from <AcuSolve installation directory>\model_files\tutorials\AcuFieldView\ to a working directory. See Tutorial Data for more information.

For Windows users, in order to take advantage of the restarts provided for this tutorial, you will need to make sure that the properties for your AcuFieldView shortcut on the Start menu do not include a Start in entry. To change that property, browse to the AcuFieldView shortcut on the Start menu, right-click, and select Properties. The Start in field can be found on the Shortcut tab in the AcuFieldView Properties dialog. Note that this step is only necessary because the restart files use relative paths.

Figure 1.

Solve the Case with AcuConsole and AcuSolve

  1. Start AcuConsole.
  2. Open vortex_shedding.acs.
  3. Run AcuSolve to calculate a transient solution.
  4. Exit AcuConsole.

Convert the Dataset to FieldView Unstructured Format (FV-UNS)

AcuFieldView's native format for reading data is known as the FV-UNS format. This format has been optimized for file size and performance. When using this format, data read times are reduced in comparison to reading the data directly from the AcuSolve database. When the data will be read multiple times, this format is preferred. This step explains how to perform the conversion of AcuSolve results to FV-UNS format.
  1. Open an AcuSolve Cmd Prompt or Linux terminal.
  2. Change the directory to the location of the solved problem, <your working dir>\vortex_shedding\.
  3. Execute AcuTrans with the following command line arguments: acuTrans -out -to fieldview -ts A -extout.
  4. Exit the command window or terminal when AcuTrans completes the conversion.

Start AcuFieldView and Read a Transient Dataset

  1. Start AcuFieldView.
  2. Click View > Background Color and select white.

    Figure 2.
  3. Click Close.
  4. Click File > Data Input > AcuSolve [FV-UNS Export].
  5. Click Read Grid or Combined Data.
  6. Select vortex_shedding_step000003.fv and click Open.
  7. In the Function Subset Selection panel, ensure that all function names are selected and click OK.
  8. Click Yes to treat all files as a transient set.
    After read in, you will be presented with an isometric view of the data outline.
  9. Close the FV-UNS data input panel.
  10. Click in the Transform Controls toolbar or View > Defined Views to open the Defined Views panel.
  11. Click +Z for the VIEWING DIRECTION.
  12. Close the Defined Views panel.
  13. Click Bound to visualize the cylinder using the Boundary Surface panel.
  14. Click Create, select OSF: Cylinder, and click OK.
  15. Change Line Type to Thick and change the Geometric color to black.

    Figure 3.
  16. Zoom into the cylinder (with Object set as World on the Viewer toolbar) with the right mouse button (M3).

    Figure 4.
  17. Click Coord to visualize the vortex shedding using the Coordinate Surface panel.
  18. Click Create and change the COORD PLANE to Z.
  19. Change the COLORING to Scalar and the DISPLAY TYPE from Mesh to Contours.

    Figure 5.
  20. In the Colormap tab in the Coordinate Surface panel, change the Number of Contours to 32 and the Colormap from Spectrum to NASA-1.
    You can also set the colormap on the Scalar Colormap Specification panel from the Edit menu.

    Figure 6.
  21. On the View menu turn off the Axis Markers and Perspective.

    Figure 7.
    Note: The image on your screen may differ from what is shown based on the zoom level.

Figure 8.

Perform a Transient Sweep

In this step, you will use the Transient Data Controls panel to visualize the movement of the vortex "tail" as you perform a transient sweep. You will also create a grid of coordinate surfaces in order to better see the extent of the movement.
  1. Click Tools > Transient Data.
  2. Use the slider to set the initial TIME STEP to 3 and click Apply.
  3. Activate Sweep.
    The flow contours develop from a symmetric initial condition to the transient vortex shedding seen as the blue contours of the vortex "tail" sweeping up and down. Notice that the vertical extent of the "tail" is approximately that of the unit cylinder, and note that the center of the cylinder is the point [0,0,0]. This information will be used to create a "grid" in the following steps.

    Figure 9.
  4. Click View > Minimum Time Between Frames and set the Minimum Time Seconds to 0.1 to slow the sweep animation.
  5. Click Sweep again to stop the animation.
  6. Click OK in the Transient Data Controls message panel.
  7. Reset the current TIME STEP to 3 using the slider or by entering 3 in the TIME STEP field.
  8. Click Apply and close the Transient Data Controls panel.
  9. In the Coordinate Surface panel (Visualization Panels > Coordinate Surface), click Create.
  10. Change COLORING to Geometric, DISPLAY TYPE to Mesh, COORD PLANE to X and the Current value to 1.0.
  11. Create additional vertical X coordinate surfaces at 1.5, 2.0, and 2.5.
    These will be coordinate surface numbers 3-5.
  12. Create horizontal Y coordinate surfaces at 0.0, 0.5, 1.0, and at -0.5 and -1.0.
    These will be coordinate surface numbers 6-10.
  13. Use the Transient Data Controls to Sweep through the time steps again.
    Notice how the blue contoured "tail" sweeps through the points [1.5, 0.5] and [1.5, -0.5]. These two points will be used to create small coordinate surfaces to seed onto in the next step.
  14. Click Sweep to stop the animation.
    The following image is from time step 201.

    Figure 10.
  15. Reset the current TIME STEP to 3.

Create Streamline Seeding Surfaces

In this step, you will create seeding surfaces at the vertical extents of the "tail" swing. You will create two circles by thresholding coordinate surfaces. First you will create the two threshold functions, circles centered on [1.5, 0.5] and [1.5, -0.5].
  1. Click the icon.
  2. In the Function Specification panel, click Create.
  3. In the Function Formula Specification panel, create the formula (("X"-1.5)^2+("Y"-0.5)^2)^0.5 by clicking the Operations/Keys and selecting the X and Y Quantities.
  4. Click OK.
  5. In the Function Name Input panel, name the function Center-1 and click OK.
  6. Create the formula (("X"-1.5)^2+("Y"+0.5)^2)^0.5, click OK, name it Center-2 and click OK.
  7. In the Coordinate Surface panel, create a Z coordinate surface.
    Change the Geometric color of the surface to blue and change the DISPLAY TYPE to Constant shading.
  8. Scroll down to the Threshold Function controls, click Select, select Center-1 from the Function Selection panel, and click Calculate.
  9. Turn on Threshold Clip and change the Max to 0.25.
  10. Scroll to the top of the Coordinate Surface panel, if needed.
  11. Create another Z coordinate surface. This surface will inherit most of the properties of the previous surface.
  12. Change the Threshold Function to Center-2.
  13. Change Max in the Threshold Function section to 0.25.

    Figure 11.

Create Streamlines

In this step, you will seed the threshold coordinate surfaces from the previous step. This will be made easier by turning off the visibility of the contour coordinate surface.
  1. Double click a contour in the main visualization window to open the Coordinate Surface panel (Surface ID: 1) and turn Visibility off.
  2. Click Stream .
  3. Create a streamline rake.
  4. Change the seeding Mode from Add (default) to Seed a Surface.

    Figure 12.
  5. With the mouse pointer above the upper of the two blue coordinate surfaces (avoid clicking on the grid), click Ctrl+left mouse (M1) to select the surface.
    An "x" should appear on the selected surface.
  6. Click OK to add the 10 seeds.
  7. Make the following changes to the Calculation Parameters at the bottom of the Streamlines panel (you may need to scroll down to see the bottom panel).
    1. Turn Time Limit on using the default value of 1 to limit the duration of all streamlines in this rake to a maximum of 1.
    2. Increase the Step size from the default of 3 to 9.

      Figure 13.
  8. In the Streakline Parameters section, change the Release Interval to 1.
    This will be used in streakline calculations later on.

    Figure 14.
  9. Click Calculate to show the time limited streamlines.
    Note: The appearance of the streamline pattern will depend on the current time step.
  10. Create a second rake and repeat the above steps as necessary for the other threshold coordinate surface.
    You may need to scroll up to see the top of the panel.

    Figure 15.

Create Streaklines

In this step, you will sweep through the transient dataset. While doing this, you will create a streakline export file and a flipbook (movie) of the particles.
  1. Turn off Show Seeds for both rakes.
  2. Zoom out and move the cylinder to the left edge of the graphics window to better see the vortices being propagated downstream of the cylinder.
  3. Click Anno to open the Annotation panel.
    Tip: To see the icon on the toolbar, you might need to expand the toolbar with the icon.
  4. Click Create Text to create titles showing the time step and solution time being displayed.
  5. In the Annotation Create panel, enter in the string: Time Step: %%N1 Solution Time: %%T1 and click OK.
    The special notation %%N1 means show the time step of dataset #1 and %%T1 means show the solution time of dataset #1.

    Figure 16.
  6. Change the default font, Lee Bold, and increase the Size as desired.
  7. Move the title with the Shift+left mouse (M1) following the hints on the Annotation panel.

    Figure 17.
  8. Click Tools > Flipbook Build Mode to prepare to create a flipbook.
  9. Click OK to dismiss the Flipbook Size Warning panel.
  10. Click Tools > Transient Data.
    Because Flipbook Build Mode is on, the Sweep button on the Transient Data Controls panel is replaced by Build.
  11. Set the TIME STEP to 3.
  12. Activate Build.
    The Streakline Export panel prompts you to save the streaklines, based on your visible streamline rake seed locations, to a Particle Path file, which makes subsequent streakline display much simpler.
  13. Click Yes on the Streakline Export panel.
  14. In the Export Streaklines panel name the file vortex_1.fvp and save the file.
    Once the 75 frames are created, the Flipbook Controls panel can be used to play and Save the animation.
  15. Click Frame Rate to open the Minimum Time Between Frames panel and adjust the Minimum Time Seconds to slow or speed up the flipbook replay.

    Figure 18.

    This image is from frame 63, which captured time step 189

  16. Close the Flipbook Controls panel.
  17. Click OK to dismiss the warning in the Flipbook Exit Conformation panel.

Import Streaklines and Improve Your Animation

In this step, you will import your previously exported streaklines. You will then create another animation which will allow you to better see the vortices being shed off of the cylinder.
  1. In the Transient Data panel, set the TIME STEP to 3.
  2. In the Streamlines panel turn off the Visibility for each rake.
    Tip: The arrow buttons at the top of the panel can be used to switch between Rake ID 1 and Rake ID 2.
  3. Click the Paths icon or Visualization Panels > Particle Paths.
  4. Click Import.
  5. Browse to and select the streakline export (particle path) file, vortex_1_3.fvp, that you previously created.
  6. Change the COLORING to Scalar and DISPLAY TYPE to Spheres.
  7. Click Select and select x-velocity as the Scalar Variable for the particles.
  8. Click Tools > Transient Data to open the Transient Data Controls panel.
  9. Advance the TIME STEP to 225 and click Apply.
    This shows the positions of the particles at their furthest extent. When the TIME STEP slider is moved and applied, the positions of the particles change to match their locations at the selected time step.

    Figure 19.
  10. Set Object to World on the Viewer toolbar.
    Resize the image in the modeling window so that more can be seen. Use zooming out (M3) and left translation (M1).

    Figure 20.
  11. Open the Coordinate Surface panel.
  12. Turn off the Visibility from the Surface tab for Surfaces #11 and #12.
  13. Turn on the Visibility of Surface #1 (the contour surface).
  14. In the Transient Controls panel, move the slider back to TIME STEP 3 and click Apply.
  15. Turn Flipbook Build Mode on (Tools > Flipbook Build Mode).
  16. Activate Build in the Transient Data Controls panel to create a flipbook.
  17. Save the flipbook as vortex_animation_1.avi when the creation is complete.

    Figure 21.

Use Scripts

In this section, you will build a flipbook and produce a streakline export file at the same time using an AcuFieldView script file. You will then import the exported streaklines and sweep through the dataset again, creating a flipbook of the imported particles paths. This tutorial can also be used in conjunction with DataGuide™ .
  1. Start AcuFieldView with the DataGuide™ switch (add the -p2 command-line switch to your usual AcuFieldView start-up command.) For Windows, run AcuSolve Cmd Prompt in your AcuSolve program group and start AcuFieldView using acuFV -p2.
  2. Click Views > Graphics Layout Size > 640x480 NTSC.
    This creates an animation file of a standard size.
  3. Click File > Data Input > AcuSolve [FV-UNS Export] to read in the FV-UNS data.
  4. Click Read Grid or Combined Data.
  5. Select vortex_shedding_step000003.fv and click Open.
  6. Click File > Open Restart > Complete, No Data Read to read in the complete restart called ..\vortex_shedding\restart\vortex_shedding.dat.

    Figure 22.
  7. Click File > Open Restart > Script to read the script restart called create_streakline.scr from the ..\vortex_shedding directory.
    This script, shown below, automatically performs a sweep using 100 seeds and saves the streakline export file, 100_seeds.fvp, a binary particle path file, along with the flipbook simple_streak.miff, for Linux, or simple_streak.avi, for Windows.
    !..AcuFieldView Script:
    ! Start recording a flipbook
    RECORD ON simple_streak
    ! Performs a transient sweep &
    ! saves a streakline file
    SWEEP TIME LOOP 1 1 1 100_seeds.fvp
    ! Turn off recording
    !..End of Script
  8. Exit AcuFieldView.
  9. Make sure that the file 100_seeds.fvp and the flipbook were created.
  10. Start AcuFieldView again, this time without using any DataGuide™ command-line switches.
  11. Click File > Open Restart > Complete to read in the complete restart called ..\vortex_shedding\display_streakline.dat.
    This restart imports the streaklines as particle paths, removes the coordinate lines, draws the cylinder using smooth shading, changes the view to better display the vortex shedding, sets the scalar function to use VecZ(curl(velocity)) for coordinate surface 1, relocates the surface plane to .05, and turns on presentation rendering for better looking particles.

    Figure 23.
    Note: You may need to resize your AcuFieldView window or move the model to get the view shown above.
  12. Open the Coordinate Surface panel and set the Surface ID to 1.
  13. On the Colormap tab, change the scalar min/max values to -10 and 40, respectively. The Number of Contours should be 32. Alternately, these changes can be made using the Scalar Colormap Specification panel.

    Figure 24.
  14. Click File > Open Restart > Script to read in the second script restart called ..\vortex_shedding\display_streakline.scr.
    This script performs a transient sweep and saves an animation called final_streak.miff, for Linux, or final_streak.avi, for Windows.
    !..AcuFieldView Script which:
    ! Starts recording a flipbook
    RECORD ON final_streak.miff
    ! Performs a transient sweep
    ! (no streakline file saved)
    ! Turns off recording
    !..End of Script
  15. When the script completes, exit AcuFieldView (if desired) and play the two flipbook animations, simple_streak and final_streak.

    Figure 25. This image shows final_streak.avi at time step 213