Surface Average

The surface average of a scalar quantity ϕ is computed on a surface as:

Figure 1. EQUATION_DISPLAY
Surface Average1aϕda=fϕfAffAf
(404)

where ϕf is the face value of the selected scalar and Af is the face area.

For axisymmetric cases, the mesh is assumed to be swept through an angle of 1 radian. For applications that use a mass flow inlet, the mass flow is therefore given in kg/rad s. Any volumetric or area quantities reported for the Axisymmetric model are assumed to be for a sector of 1 radian.

For two-dimensional cases, the mesh is assumed to have a unit depth (in SI units). Therefore any volumetric or area quantities that are reported for the two-dimensional model are assumed to be “per meter”.

To compute a generalized area average, you can specify an additional field function w f as a weighting function. The surface average with weighting is:

Figure 2. EQUATION_DISPLAY
w ϕ d a w d a = f w f ϕ f A f w f f A f
(405)

Surface Average Report Properties

Units
Units that are used for specifying the quantity.
Field Function
Scalar field function value ϕ upon which the report is based.
Weighting Function
Optionally select a field function to be used as a weighting function in addition to area for this report. The Weighting Function is always evaluated at faces independent of whether the Smooth Values option is activated.
Parts
A list of parts that is used as the source for this report. Opens the in-place part selector for editing.
Representation
Selects a representation. Additional selections appear as representations that are added to the simulation.
Smooth Values
When this property is activated, the report is calculated using node (interpolated) values of the chosen quantity rather than cell values.