Expression Report

The expression report depends on a combination of reports, except for system reports. It works with the field function generated for each report you want to use.

This report is represented in the simulation tree by a node, which has its own properties but is subject to the report node’s pop-up menu.

You can post-process scalar values for individual parts, in addition to the overall report results. See Accessing Report Results on a Per-Part Basis.

For example, suppose that you want to plot the pressure drop between two boundaries, such as the inlet and outlet of a pipe. Assuming you created a report of surface average pressure for each boundary, you can directly create a report of those reports by entering the following function names in the Definition property:

$AveragePressure1Report - $AveragePressure2Report

The field functions that can be used to define expressions cannot be a function of space; they have to evaluate to a single number as the expressions are constants in space. Variables such as $Time, $TimeStep and $Iteration, as well as the field functions associated with reports, are valid. Variables such as $Temperature or $Pressure have different values at every different point in space and cannot be used in expressions.

Some expression reports return values that wrap-around as the solution proceeds. For example, if you have a report that returns the rotation angle of a fan, then you know that the angle must always fall between zero and $2 π$ . If you have an update event, such as a delta or waypoint event, that depends on the difference between two successive values of this report, the event must account for the periodic nature of the reported values. In the following diagram, the difference between values a and b is d₁ + d₂ rather than d₀.

Use the Periodicity property to identify reports whose values wrap-around. When calculating the difference between two values, Simcenter STAR-CCM+ chooses the minimum of $d_{0}$ and $d_{1} + d_{2} = M - b + a - m$ .

Expression Report Properties


Units	Units that are used for specifying the quantity.
Definition	The formulation of this report using the function name of the Simcenter STAR-CCM+ field functions corresponding to the reports selected. Entering an invalid definition causes an Unable to compile error message.
Periodicity	When set to Periodic, this property tells related update events that values from this report wrap around when they reach a certain value. This behavior must be respected when calculating the difference between successive reported values. Provide the minimum and maximum wrap-around values in the Periodic Range sub-node.
Dimensions	The physical dimensions of this report, which you can customize.
Delta Value	When activated, specifies handling the value as a delta (interval) quantity for units conversion, rather than absolute. This only affects expressions that use units with a non-zero Offset property. For example, if you define a Temperature expression report as `<10 C>`, the default absolute value is approximately 283 K. But suppose you want to specify an increase of 10 deg C, that is, a delta value. In that case, set the Delta Value option and the expression evaluates to 10 K. If the temperature outside is 10 deg C, that means it is 283 K. But if the temperature warms up by 10 deg C, that means it has increased by 10 K (not 283 K). The Delta Value option allows you to distinguish between those two uses.

Periodic Range Properties


Periodic Maximum	The highest value expected for this expression report.
Periodic Minimum	The lowest value expected for this expression report.