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Transient Series 2: Understanding Transient Data through Extractions


Description

This video shows techniques in Tecplot 360 to reduce the data that needs to be analyzed using two built in extraction methods, including extracting points from a geometry line and probing over time.

In the second video of the transient series, we will cover techniques to reduce the data to be analyzed using various built in extraction methods. This includes extracting points from a geometry line and probing over time. We already have our data loaded into Tecplot from the first video in the Transient Series.

  1. Extract a range of values using a user defined line. To do this, draw a polyline by clicking the Create Polylines Geometry button on the top tool bar then clicking at the point where the polyline will begin. By pressing V on the keyboard, it will lock it vertically then double click to end it.
  2. At this point, there are two methods of extraction. (You could right-click on the polyline and click “Extract Points…” to extract a single time step, but this won’t be here as we want to see all time steps.) To see all time steps, go to Data > Extract > Extract Geom Over Time. Select 50 for the number of points to extract. Then click OK. Tecplot 360 is extracting the same polyline points for all time steps and will create new linear zones for each of these time steps.
  3. To investigate the newly extracted data, create a new frame using the button in the top tool bar, click and dragging to create the new frame, tile the frames by going to Frame > Tile Frames, tile frames horizontally, then fix the view of the top frame by re-centering the blades.
  4. In the bottom frame, change the plot type in the Plot Sidebar to 2D Cartesian. This data is typically viewed as XY-line plots, however, they don’t have the same transient data capabilities as 2D plots do. We want to be able to link these two frames with time for a better visualization of the data.
  5. Turn off all of the zones except for the extracted data by going into the Zone Style dialog. Notice how the extracted data have been saved in a single strand so it will show up as a single field map. Right-click on the Extracted Points zone under the Show Zone column and choose “Show Selected Only.”
  6. Next, ensure the variables of interest are on the axes by going to Plot > Assign XY. Choose Y to show on the X-axis and Pressure to show on the Y-axis. Then click OK. Turn on Mesh in order to see the line.
  7. The axes also need to be set up properly with the right axis ranges and to ensure they are independent. This is done by going to Plot > Axis… and selecting Independent in the dialog. Click on the frame containing the line data and press Ctrl + F on the keyboard to fit the view. Click back into the Axis dialog and click on the Y button at the top of the dialog box. Change the range so that -100 is the minimum and -30 is the maximum. Click Close.
  8. Before animating, link the two frames in time, go to Frame > Frame Linking, toggle on Solution Time, then Apply Settings to All Frames of this group. Verify that the frames were linked successfully by clicking the top frame and ensuring the solution time box is still checked. Click Close.
  9. Next, add a text element to show solution time by clicking on the Add text button in the top toolbar. Click where you would like to add the text in the top frame and the Text Details dialog will pop up. Type Solution Time: &(SolutionTime). (&(SolutionTime) is a keyword that will show the current time step in the frame.) Click Accept.
  10. Animate the frames by clicking the Play button in the plot sidebar. By animating the lines in the bottom frame, we see how the blades affect the resulting pressure distribution as they rotate.

Now that you know how to extract data using a 2D line, you will now see how to extract data at a single point over time. Delete the bottom frame by selecting it the pressing Delete on the keyboard then click OK.

  1. Go to Tools > Probe to Create Time Series Plot. Once active, select a point as close to (0,0) as possible. You can see the current mouse coordinates in the bottom right corner of the workspace. Once the probe is placed, Tecplot 360 is again going through and loading data from all time steps, performing a standard probe and extracting the resulting data into a single line. This method also conveniently sets up a new frame in addition to setting up frame linking for a plot marker you will see in a moment.
  2. Tile the frames horizontally by going to Frame > Tile Frames and choosing horizontal.
  3. Animate by time by pressing Play in the Plot sidebar. Notice how both plots are animating and the black vertical bar is indicating the current time step.

We will investigate the properties of this resulting plot in the video 3 of the Transient series, which covers Fourier transforms.

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