Plotting Graphs

Plot the lift and drag coefficients to determine when the analysis has converged.

Use the following steps:
  1. Right-click the Reports node and select New > Flow / Energy > Force Coefficient.

    A new report node named Force Coefficient 1 is created.

  2. Rename this node Drag Coefficient then enter the following information:
    Property Value
    Units Empty
    Coordinate System Laboratory > Cartesian 1
    Direction [1.0, 0.0, 0.0]
    Force Option Pressure + Shear
    Reference Pressure 0.0 Pa
    Reference Density 1.177 kg/m^3
    Reference Velocity 252.0 m/s
    Reference Area 1.0 m^2
    Parts [Fluid: wall]
    Number of Bands 0
    Representation Volume Mesh
    Smooth Values Deactivated


  3. Right-click the Drag Coefficient node and select Create Monitor and Plot from Report.

A new plot node appears named Drag Coefficient Monitor Plot.

  1. Select the Drag Coefficient Monitor Plot node and set the Title to Drag Coefficient Monitor Plot.

To create a plot for the lift coefficient:

  1. Repeat the steps described above to create and display a plot for the lift coefficient. All settings are the same as for the drag coefficient.
  2. Rename the report node Lift Coefficient and set its Direction property to [0.0, 1.0, 0.0].
  3. Select the Lift Coefficient Monitor Plot node and set the Title to Lift Coefficient Monitor Plot.

Experimental data for the pressure coefficient on the airfoil are provided in file aero_exp.xy in the doc/startutorialsdata/compressibleFlow/data directory. Plot the data on a graph alongside the results of the analysis.

To plot the experimental data:

  1. Right-click the Tools > Tables node and select New Table > File Table.
  2. Set Files of type: to (*.xy), then locate and open the file aero_exp.xy.
  3. Right-click the Plots node and select New Plot > XY Plot.
  4. Right-click the XY Plot 1 > Data Series node and select Add Data.
  5. In the Add Data Providers to Plot window, select aero_exp.
  6. Select the Data Series > aero_exp node and set aero_exp for the Table property.
Make sure that the X Column and Y Column properties are as shown below:

A graph of the experimental data appears in XY Plot 1.

To add the numerical data to the same graph:

  1. Select the XY Plot 1 node and click the Parts property.
  2. Select Fluid: wall in the XY Plot 1 - Parts dialog.
  3. Select the Y Types > Y Type 1 > Scalar Function node and set Pressure Coefficient for the Field Function property.

The initial pressure coefficient is shown in the XY Plot 1 as being zero everywhere.

The pressure coefficient requires specification of a reference pressure and a reference velocity.

  1. Select the Automation > Field Functions > Pressure Coefficient node and enter a Reference Density of 1.177 kg/m^3 and a Reference Velocity of 252 m/s, have the settings shown below:

The usual convention in aerodynamics problems is to reverse the y-axis orientation in pressure coefficient plots.

  1. Select the XY Plot 1 > Axes node and set the following properties:
    Property Setting
    Preferred X-Axis Left Axis
    Preferred Y-Axis Bottom Axis
  2. Select the Axes > Left Axis and activate Reverse.
  3. To set the correct titles for the plot:
    1. Select the Plots > XY Plot 1 node and set Title to Pressure Coefficient Comparison.
    2. Within XY Plot 1 > Axes, select the Bottom Axis > Title node and set Title to Distance (m).
    3. Select the Left Axis > Title node and set Title to Pressure Coefficient.
  4. Save the simulation.