Having run a simulation on the Piper Cherokee, the next step is to investigate and analyze the results. Do this by looking at the solution residuals and the outputs, Lift and Drag, that we defined earlier, both to understand the convergence behavior of the simulation and to see how well this aircraft performs. We can also leverage visualization tools to further investigate the flow solution.
If you've just run this simulation, the Simulation results tab should be open. Within the 3D Viewer you'll see a box on the left, detailing the status of the simulation, including the number of iterations.
Now, in the simulation control panel, click on Outputs. In the properties panel below you should see that:
The final Lift value was about 13,500-13,900 N.
The final Drag value was about 850-900 N.
At the bottom of the 3D Viewer you'll see a chart showing the convergence history of this simulation. By default this will show the Solution Residuals, but you can also change this to display the Lift or Drag using the dropdown on the left. In this project you should see that:
While the residuals are still converging, the lift and drag appear to be highly converged.
We can also do some simple inspection of the results in the 3D Viewer, though in subsequent parts of this project we'll work more extensively with visualization tools. First ensure the aircraft is in the center of the 3D Viewer:
With the Simulation results tab open, check the Airplane surface is visible and the Far Field is hidden. By scrolling to the Visualizations section in the control panel, also ensure that any existing visualizations are also hidden.
Fit the airplane to the 3D Viewer window so that it is clearly visible.
In the visualization toolbar at the top left of the 3D Viewer, you can switch the display quantity using the dropdown menu. By default this shows Absolute Pressure (Pa), but you can choose between a range of scalar and vector quantities. If you choose a vector quantity, you will also need to select the component of this vector (Magnitude, X, Y, Z) to display in a following dropdown. On the right side of the 3D Viewer a color bar legend will indicate which colors correspond to which values of your chosen quantity.
Note: If you choose to show velocity on a wall with a no-slip or wall-model boundary condition, the values at all points on that wall will be zero.
Similarly, certain quantities are only available on surfaces (for example y+, heat flux, etc.). The value of these quantities on slices and clips is zero because they are not computed inside the volume.
To experiment with using this basic visualization functionality:
Select Pressure (Pa) as the display quantity.
Click on the color bar. This will open a window where you can adjust the colors.
By default, the color map corresponds to the Global range of all values in the entire domain. To provide a more useful representation just for the airplane surface, click to select a Visible range. (You can also fine-tune by inputting your desired minimum and maximum limits or by dragging the limits on the slider.)
Also by default, the Colormap will be set to Jet. Select this dropdown and change to Cool to Warm.
Click the Done button to apply these changes.
Another way to quickly analyze the results on a surface is to use the Probe tool from the list of visualization tools above the 3D Viewer. With this tool selected, click on any location on a visible surface in the 3D Viewer to see the coordinates of that point and the value of the currently selected display quantity.