Graphing fields

A field relates a dependent domain to an independent domain. You can use the plotting commands to visualize this relationship.

You can create two types of graphs for fields:

• 2D graphs depict how the dependent variable varies with respect to a single independent variable.

• 3D graphs depict how the dependent variable varies with respect to two independent variables.

After you create a 2D or 3D graph, you can change the graph title, axis labels, axis ranges, graph style, colors, among others.

• For information on how to change the graph title, axis labels, axis ranges, and so on, see Edit display properties of graph objects.

• For information on how to change the graph style, the colors used in the graph, line styles and widths, and so on, see Edit Style dialog box

2D graphs

2D graphs plot a dependent variable versus a single independent variable. The fields can have an independent domain that consists of one or more independent variables. If the field has an independent domain with two or more independent variables, you specify which independent variable to assign to the horizontal axis (the abscissa) of the graph. The other independent variables are referred to as control variables. To create a 2D graph, you must specify a numerical value for each control variable.

For example, suppose a field represents pressure as a function of Cartesian coordinates. Mathematically, you can write this relationship as:

p = f(x,y,z)

If you assign x to the horizontal axis, y and z are the control variables. To create the 2D graph, you must specify numerical values for the control variables. When you specify values for the control variables, the multivariate functional relationship simplifies to:

p = f(x,y0,z0) = g(x)

where y0 and z0 are the numerical values for the control variables.

You can overlay up to 50 2D graphs. The fields that you want to overlay must have the same independent and dependent domains as the field for the existing graph.

For example, you can overlay the 2D graph of a frequency-force field over the 2D graph of another frequency-force field, but you cannot overlay a frequency-force field over a frequency-displacement field.

2D graph of pressure vs. a single coordinate

3D graphs

3D graphs plot a dependent variable versus two independent variables. The fields can have an independent domain that consists of two or more independent variables. If the field has an independent domain with three or more independent variables, you specify which two independent variables to assign to axes for the independent domain of the 3D graph. The other independent variables are referred to as control variables. To create a 3D graph, you must specify a numerical value for each control variable.

For example, suppose a field represents pressure as a function of Cartesian coordinates. Mathematically, you can write this relationship as:

p = f(x,y,z)

If you assign x and y to the two axes for the independent domain, z is the control variable. When you specify a value for z, the multivariate functional relationship simplifies to:

p = f(x,y,z0) = g(x,y)

where z0 is the numerical value for the control variable.

You cannot overlay 3D graphs.

3D line graph of pressure vs. a pair of Cartesian coordinates

In the 3D graph figure, pressure is plotted against the x and y coordinates. The software creates the 3D graph from a series of values for pressure at discrete (x,y) coordinates that form a grid in the xy-plane.

• For formula fields, the software obtains the pressure values by evaluating the formula for the field at each grid location.

• For table fields, the software obtains the pressure values by performing a table lookup at each grid location. Thus, for table fields, the plotted values depend on the interpolation method.

The (x,y) coordinates where the software calculates the pressure depend on your settings in the Field XY Graph3D dialog box, in the Bounds groups.

• For a formula field, or a table field with the Plot at all tabular data points check box cleared, the (x,y) coordinates always form a uniformly-spaced grid.For example, in the Bounds groups, suppose that you specify the Minimum and Maximum boxes such that the ranges for the x and y coordinates are [0,1] and [5,10], respectively.If in the Number of points box for the x coordinate you enter 4, then the values of x that the software uses to form the grid are 0, 0.333, 0.667, and 1.If in the Number of points box for the y coordinate you enter 5, then the values of y that the software uses to form the grid are 5, 6.125, 7.5, 8.725, and 10.For this example, the software uses a grid of 20 ( = 4 x 5) lookup points to create the graph.When the software creates a line style graph for this case, it creates a trace for each y value. Thus, five traces are created. The first trace connects the pressure values at (0,5), (0.333,5), (0.667,5), and (1,5); the second trace from (0,6.125), (0.333,6.125), (0.667,6.125), and (1,6.125); and so on.Thus, the value that you specify in the Number of points box, determines the number of traces.

• For a table field with the Plot at all tabular data points check box selected, the (x,y) coordinates may not form a uniformly spaced grid because the software includes additional y values (or x values if x is listed in the Field XY Graph3D dialog box, in the Independent Variable 2 group, in the Variable box), so long as the values are within the range specified in the Bounds group for the second independent variable, in the Minimum and Maximum boxes.Continuing the previous example, suppose the Plot at all tabular data points check box is selected, y is listed as the second independent variable in the Field XY Graph3D dialog box, and the table field contains the following tabular data:XYPressure0-1.502.000.3003.600.403.254.500.756.902.201.058.101.201.3011.500.601.5014.000.60For the x coordinate locations, there is no change, and the values of x that the software uses to form the grid are 0, 0.333, 0.667, and 1.However, for the y coordinate locations, the values of y that the software uses to form the grid are now 5, 6.125, 6.90, 7.50, 8.10, 8.725, and 10. Because the Plot at all tabular data points check box is selected, 6.90 and 8.10 are added.For this example, the software uses a grid of 28 ( = 4 x 7) lookup points to create the graph.When the software creates a line style graph for this case, it creates a trace for each y value. Thus, seven traces are created. The first trace connects the pressure values at (0,5), (0.333,5), (0.667,5), and (1,5); the second trace from (0,6.125), (0.333,6.125), (0.667,6.125), and (1,6.125); and so on.Thus, the values that you specify in the Field XY Graph3D dialog box, in the Independent Variable 2 group, in the Number of points box, and the tabular y values that are within the plot range, determine the number of traces.

The previous examples use pressure as the dependent domain for the field and (x,y) coordinates as the independent domain. However, the software uses the same procedure for other combinations of dependent and independent domains.

Graphing structured 2D tabular data

When graphing a table field, you can direct the software to create the graph directly from structured 2D tabular data that was imported with the Imported Data is in Structured Data Format check box selected in the Table Data Import dialog box. When you use this capability, the grid of locations at which the software constructs the graph coincides with the tabular data points.

For example, consider the following structured 2D tabular data for pressure as a function of (x,y) coordinates.

X	Y	Pressure
2.00	2.00	4.00
3.20	2.00	3.60
4.80	2.00	2.80
2.00	3.00	3.00
3.20	3.00	2.00
4.80	3.00	1.30
2.00	6.00	2.20
3.20	6.00	1.20
4.80	6.00	0.60

When the software creates a line style graph for this case, it creates a trace for each value of the independent variable that is listed in the Field XY Graph3D dialog box, in the Independent Variable 2 group, in the Variable box.

Assuming that y is listed in the Variable box, the values of y at which the software creates traces are 2.00, 3.00, and 6.00.

Line graph of the tabular data with the Y-coordinate as the second independent variable

The surface graph for the same tabular data is constructed from triangular surfaces that the software obtains by diagonally splitting the quadrilateral shapes inherent to the tabular data.

Surface graph of the tabular data. The black lines outline the quadrilateral shapes inherent to the tabular data

Where do I find it?

Create a 2D graph

Application	Pre/Post
Simulation Navigator	Right-click the node for the field node and choose Plot(XY)

Create a 3D graph

Application	Pre/Post
Simulation Navigator	Right-click the node for the field node and choose Plot(XYZ)

Create a 3D graph directly from structured 2D tabular data

Application	Pre/Post
Prerequisites	A table field constructed from structured 2D data that was imported with the Imported Data is in Structured Data Format check box selected in the Table Data Import dialog box
Simulation Navigator	Right-click the table field node and choose Plot(XYZ)
Location in dialog box	Table Field Options list→Show Structured Data as Lattice

How do I

Create a 2D graph of a formula field

Create a 2D graph of a table field

Create a 3D graph of a formula field

Create a 3D graph of a table field

Create a 3D graph of structured 2D data

Learn more

Displaying fields

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Graphing fields, Simcenter 3D 2021.1 Series

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