Understanding How Contour Values are Computed

The computations necessary to produce a contour plot from results depend on whether the contour plot displays values for a node-based quantity, such as displacement or velocity, or for an element-based quantity, such as stress or strain.

This page discusses:

How node-based field output variable contour values are computed

For contour plots of node-based field output variables, contour values are obtained directly from the quantities on the output database. These values are then used without further computation to produce colored lines or colored bands on the surface of your model.

How element-based field output variable contour values are computed

For contour plots of element-based field output variables, computations are applied to the output database results to form the contour values. The computations vary according to the following criteria:

  • the quantity you choose to plot (field output or discontinuities),
  • the averaging options you select,
  • the results regions you select,
  • the compatibility of elements included in the plot, and
  • the type of contour plot you request (line, banded, or quilt).

The type of contour plot that you request governs the extrapolation applied to the results read from the output database. For line-, banded-, and isosurface-type contours of element-based variable values, the app extrapolates results to the nodes. By default, the results are conditionally averaged after the app performs any necessary transformations and computes any requested scalar components or invariants; if desired, you can compute invariants after the results are averaged. For quilt-type contours of element-based variable values, the app extrapolates results to the element faces on the surface of your model and then takes a weighted sum to produce a single value per face. Since quilt contour values are computed for each element face individually with no averaging across element boundaries, a quilt contour plot is an effective means of displaying results on an element-by-element basis. You can choose quilt-type contours only for element-based field output variables.