30.3.1 Generating a Flux Report

To obtain a report of mass flow rate, total heat transfer rate, total sensible heat transfer rate, or radiation heat transfer rate on selected boundary zones, use the Flux Reports dialog box (Figure  30.3.1).

Reports Fluxes Set Up...

Figure 30.3.1: The Flux Reports Dialog Box

The steps for generating the report are as follows:

1.   Specify which flux computation you are interested in by selecting Mass Flow Rate, Total Heat Transfer Rate, Total Sensible Heat Transfer Rate, or Radiation Heat Transfer Rate under Options.

2.   In the Boundaries list, choose the boundary zone(s) on which you want to report fluxes.

If you want to select several boundary zones of the same type, you can select that type in the Boundary Types list instead. All of the boundaries of that type will be selected automatically in the Boundaries list (or deselected, if they are all already selected).

Another shortcut is to specify a Boundary Name Pattern and click Match to select boundary zones with names that match the specified pattern. For example, if you specify wall*, all boundaries whose names begin with wall (e.g., wall-1, wall-top) will be selected automatically. If they are all selected already, they will be deselected. If you specify wall?, all boundaries whose names consist of wall followed by a single character will be selected (or deselected, if they are all already selected).

3.   Click Save Output Parameter.... The Save Output Parameter dialog box (Figure  30.3.2) will open where you will specify the name of the newly created output parameter, or overwrite an existing output parameter of the same type. The default report name format is report-type-n (e.g. flux-1).

Figure 30.3.2: The Save Output Parameter Dialog Box

After the output parameter is created, it is listed in the Parameters dialog box, accessed via the Parameters... button in the Reports task page. You can create any number of output parameters of this report type.

4.   Click the Compute button to display the results of the selected flux computation for each selected boundary zone. The Net Results field will show the summation of the individual zone flux results.

Additional steps must be taken prior to generating a flux report for an interior boundary zone that has the same fluid defined on either side. In such a case, the area vectors of the cell faces associated with the zone may have been automatically defined in an inconsistent manner when the mesh file was read into the solver. Since the flux for each individual cell face is calculated with respect to its area vector, such an inconsistency leads to inaccurate results when the face fluxes are summed to calculate the total flux of the boundary zone. To ensure accurate flux results for such an interior zone, you must orient the area vectors by changing the definition of the zone Type to wall. You should then change the Type back to interior and proceed to generate the flux report.

Note that the fluxes are reported exactly as computed by the solver. Therefore, they are inherently more accurate than those computed with the Flow Rate option in the Surface Integrals dialog box (described in Section  30.6).