Plotting Simulation and Experimental Data

Plot the lift and drag coefficients to determine when the analysis has reached convergence. The pressure coefficient on the wing is then compared against the experimental data [985]. In order to compare simulation results with experimental results, you create a normalized coordinate for a section of the wing.

  1. To create a plot for drag coefficient:
    1. Right-click the Reports node and select New > Flow / Energy > Force Coefficient.
    2. Rename the Force Coefficient 1 node to Drag Coefficient then enter the following information:
      Property Value
      Direction [cos(${AoA}), 0.0, sin(${AoA})]
      Force Option Pressure + Shear
      Reference Density 1.177 kg/m^3
      Reference Velocity 291.68 m/s
      Reference Area 0.7532 m^2
      Parts Regions > Fluid > Boundaries > [Fluid.OneraM6Wing] and [Fluid.TrailingEdgeSurface]
    3. Right-click the Drag Coefficient node and select Create Monitor and Plot from Report.
  2. To create a plot for the lift coefficient:
    1. Within the Reports node, copy and paste the Drag Coefficient report.
    2. Rename the copy to Lift Coefficient.
    3. Set the Direction property to [-sin(${AoA}), 0.0, cos(${AoA})].
    4. Right-click the Lift Coefficient node and select Create Monitor and Plot from Report.
Before plotting the pressure coefficient, create a unit to represent the wingspan length.
  1. To create the unit:
    1. Right-click the Tools > Units node and select New > Units.
    2. Rename the Units_1 node to b and set the following properties:
      Property Setting
      Conversion 1.1963
      Dimensions Length (In the Dimensions dialog, set Length = 1)
In the original experiments, flow data was measured along seven sections in the spanwise direction. In this tutorial, you create a section plane at spanwise location 0.8b (where b is the wingspan) and use this section for comparing computational and experimental data. You also compare the pressure coefficient data.
  1. To create a section plane at 0.8b:
    1. Right-click the Scenes > Geometry Scene 1 node and select Open.
    2. In the Simulation window, right-click the Derived Parts node and select New > Section > Plane Section.
    3. In the Create Plane Section panel, set the following values:
      Property Value
      Input Parts Fluid.OneraM6Wing and Fluid.TrailingEdgeSurface

      (Unselect the Fluid region)
      Origin [0, 0.8b, 0] m
      Normal [0, 1, 0] m
    4. Click Create and then Close.
    5. Rename the Plane Section node to y=0.8b.


  2. Create two reports that calculate the minimum and maximum x coordinates on the wing, respectively.
    1. Right-click the Report node and select New > User > Minimum.
    2. Rename the Minimum 1 node to y4_min and set the following properties:
      Property Setting
      Field Function Position > Laboratory > X
      Parts Derived Parts > y=0.8b
    3. Right-click the Report node and select New > User > Maximum
    4. Rename the Maximum 1 node to y4_max and set the same properties as the y4_min node.
    5. Right-click the y4_min and y4_max reports separately and select Run Report.
  3. Create a field function that calculates the running distance (x) with respect to the chord length (c) measured along the chord:
    1. Right-click the Automation > Field Functions node and select New > Scalar.
    2. Rename the node to x/c - y4 and set the following properties:
      Property Setting
      Definition ($${Position}[0] - ${y4_min}) / (${y4_max} - ${y4_min})
Use the field function to plot the numerical data for the pressure coefficient.
  1. To plot the numerical data:
    1. Right-click the Plots node and select New Plot > XY Plot.
    2. Rename the XY Plot 1 node to Pressure Coefficient.
    3. Select the Pressure Coefficient node and set Parts to Derived Parts > y=0.8b
    4. Select the X Type node and set Data Type to Scalar.
    5. Select the X Type > Scalar Function and set x/c - y4 for the Field Function property.
    6. Select the Y Types > Y Type 1 > Scalar Function and set Pressure Coefficient for the Field Function property.
  2. To plot the experimental data:
    1. Right-click the Tools > Tables node and select New Table > File Table.
    2. Set Files of type: to (*.csv), then locate and open the file y=0.8b_experimental_data.csv.
    3. Right-click the Plots > Pressure Coefficient > Data Series node and select Add Data.
    4. In the Add Data Providers to Plot window, select y=0.8b_experimental_data and click OK.

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

  1. Select the Pressure Coefficient > 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 node and activate Reverse.
  3. To set the correct titles for the plot:
    1. Select the Plots > Pressure Coefficient node and set Title to Pressure Coefficient Comparison.
    2. Within Pressure Coefficient > 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.