Global
Use a Global () plot to graph a scalar quantity as a function of time or a parameter. Add a Color Expression or Filter subnode as needed. Right-click a 1D Plot Group or Polar Plot Group to add this plot type.
Go to Common Results Node Settings for links to information about these sections: Data, Title, and Coloring and Style. Also see the section Expressions and Predefined Quantities.
y-Axis
This section is only available if the Two y-axes check box is selected in the Plot Settings section of the parent 1D Plot Group node’s Settings window.
Select the Plot on secondary y-axis check box to plot the y-axis data on the secondary y-axis to the right of the plot instead of the primary y-axis to the left of the plot.
y-Axis Data (1D Plots) or r-Axis Data (Polar Plots)
For a Global plot, you can plot multiple curves in the same graph using varying line styles and colors. In the table in this section, add one or more expressions to the rows under Expression to define the quantity on the y-axis for each curve, and optionally add descriptions under Description. The descriptions appear in the legends.
For this table of expressions, the Replace Expression and Add Expression buttons have the following effect:
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Click the Replace Expression () button to select a predefined quantity and replace the entire contents of the Expression table with the corresponding variable as the only expression.
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Click the Add Expression () button to insert the corresponding variable on a new row in the Expression table.
X-Axis Data (1D Plots) or θ Angle Data (Polar Plots)
From the Parameter list, select an option for what the x-axis represents: Solution number, Frequency spectrum, Phase, or Expression. For Parametric Sweep studies, and when there are multiple inner solutions, Parameter value and Time are also available. Select:
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Solution number to use the solution numbers as the x-axis data (or θ angle data for polar plots) for an eigenvalue solution or for a parametric solution with more than one parameter.
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Frequency spectrum to have COMSOL Multiphysics compute the number of frequencies and the frequency range based on the FFT (fast Fourier transform) of the time-dependent solution. The frequency spectrum code assumes that the time range selected in the plot is a whole number of periods of a periodic function. (The transform is valid for all functions, but what you get corresponds to a periodic continuation of the function outside the chosen time range.)
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To specify these values manually, select the Number of frequencies check box and enter a value in the associated field (the default is based on the number of time samples).
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Select the Frequency range check box and then enter the bounds of the frequency range in the Minimum and Maximum fields (in Hz). The FFT algorithm uses resampling based on linear interpolation. The x-axis shows the frequency (in Hz). By default, the y-axis shows the unscaled Fourier coefficients.
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Select the Scale check box to scale the values on the y-axis so that their magnitude reflects the magnitude of the original signal. The values then have the same unit as the input data for the FFT. The y-axis title includes the unit if all expressions represented on the y-axis have the same unit. The scaling makes the magnitude at 0 Hz equal to the bias or DC component of the original signal. For a pure sinusoid, the scaled value is the peak magnitude divided by the square root of 2 ().
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Phase to specify a range of phase angles for the x-axis data. The default for the Phase is range(0,0.5,2*pi) (0–360 degrees in steps of 0.5 rad). Select a Unit for the phase angle.
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Parameter value to use the x-axis data (or θ angle data for polar plots) stored in the solution for a parametric solution with a single parameter.
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Time to use time as the x-axis data (or θ angle data for polar plots) for a time-dependent solution.
Parametric Sweep Studies
Under x-Axis Data (θ Angle Data for polar plots), for Parametric Sweep studies, and when there are multiple inner solutions, select an option from the Solutions list: Inner or Outer.
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If Inner is selected, and for time-dependent studies, the Times steps are plotted on the x-axis and one line per parameter is included in the graph (as listed in the Data>Parameter values section on this page).
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If Outer is selected, one line in the graph is plotted for each inner solution and the Parameter values are plotted on the x-axis.
One example is a time-dependent problem with a geometric parametric sweep. The time steps are the inner solutions, the parameter sweep, and the outer solutions.
Quality
This section is only available when the dataset refers to a solution using a time-dependent study. You can then increase the time resolution if needed for a smooth graph plot. In the Refinement list, enter an integer between 1 (the default value) and 1000. For an increased time resolution, enter a higher refinement value.
Legends
The Show legends check box is selected by default to display the plotted expressions to the right of the plot. In plots where each line represents a certain time value, eigenvalue, or parameter value, these values are also displayed.
When Automatic is selected from the Legends list (the default), select or clear the Description, Expression, and Unit check boxes under Include to control what to include in the automatic legends (by default, it includes the description only). You can also add a prefix or a suffix to the automatic legend text in the Prefix and Suffix fields. If Manual is selected from the Legends list, enter your own legend text into the table.
Small-Signal Analysis, Prestressed Analysis, and Harmonic Perturbation Plot Settings