When the Thermal Radiation P1, Discrete
Transfer, or Monte Carlo model has been
selected, a new variable, I-Radiation, is computed.
====================================================================== OUTER LOOP ITERATION = 1 CPU SECONDS = 3.67E+01 ---------------------------------------------------------------------- | Equation | Rate | RMS Res | Max Res | Linear Solution | +----------------------+------+---------+---------+------------------+ ... +----------------------+------+---------+---------+------------------+ | I-Radiation | 0.00 | 3.6E-08 | 4.6E-07 | 5.2 3.5E-02 OK| +----------------------+------+---------+---------+------------------+
I-Radiation data is output every
nth iteration, where n is
specified by an Iteration Interval parameter (which can
be set in Solver Control > Advanced
Options > Thermal Radiation Control in
CFX-Pre). The row containing this data has its own column headings, which
override the table headings just for the row. The column headings
are:
#Itsis the number of iterations required to obtain a converged radiation solution to within a specified tolerance. This number is usually 1 unless there are reflective boundaries (emissivity less than 1). The default maximum number of iterations and tolerances are 10, and 0.01 respectively. These values can be set in Solver Control > Advanced Options > Thermal Radiation Control > Ray Tracing.Vol Chgis the maximum normalized change in volumetric absorbed radiation at convergence.Sur Chgis the maximum normalized change in surface absorbed radiation at convergence.%Lostis the percentage of ray traces lost due to tracking errors, or non-overlap boundaries at domain interfaces. Values greater than 5% are an indication of a setup error.%Imbalis the percentage imbalance of radiative energy. This value should be 0 or a small value. Otherwise, the results are not reliable.
+----------------------+------+---------+---------+------------------+ | I-Radiation | #Its | Vol Chg | Sur Chg | %Lost %Imbal | | Gray | 1 | 0.0E+00 | 0.0E+00 | 0.38 1.94 | +----------------------+------+---------+---------+------------------+
This variable is also included in the Locations of Maximum
Residuals and Peak Values of Residuals
tables that appear in the CFX-Solver Output file.
I-Radiation data is output every
nth iteration, where n is
specified by an Iteration Interval parameter (which can
be set in the Solver Control in CFX-Pre on the
Advanced Options tab). The row containing this data
has its own column headings, which override the table headings just for the
row. The column headings are:
%SD Suris the maximum normalized standard deviation of the irradiation flux at an element face on a boundary (Wall Irradiation Flux.Normalized Std Deviation). The presence of values greater than 30% indicates that the value of Number of Histories is too small to resolve the radiation field. The presence of small isolated boundary regions with values ofWall Irradiation Flux.Normalized Std Deviationlarger than 30% is an indication that the element faces in those regions were insufficiently sampled.%SD Volis the maximum normalized standard deviation of the radiation intensity within a finite element (Radiation Intensity.Normalized Std Deviation). Similar to%SD Sur, the values ofRadiation Intensity.Normalized Std Deviationare expected to be less than 30%.%Lostis the percentage of histories lost due to tracking errors or non-overlap boundaries at domain interfaces. Values greater than 5% are indication of a setup error.%Imbalis the percentage imbalance of radiative energy. This value should be 0 or a small value. Otherwise, the results are not reliable.
+----------------------+------+---------+---------+------------------+ | I-Radiation | | %SD Sur | %SD Vol | %Lost %Imbal | | Full Spectrum | | 4.6E+01 | 1.0E+02 | 0.00 0.00 | +----------------------+------+---------+---------+------------------+
The Variable Range Information table has the output
variable Radiation Intensity listed.
It should be noticed that for heat flux specified boundaries (adiabatic, for example) the specified heat flux can verified by adding
to the
boundary flow in the H-Energy flow summary.
(3–3)
An I-Radiation section is included...
+--------------------------------------------------------------------+ | I-Radiation | +--------------------------------------------------------------------+ Boundary : Airin -1.5659E+03 Boundary : Combustor Default -3.5729E+02 Boundary : Downcomer Wall -5.1864E+02 Boundary : Fuelin -1.0076E+03 Boundary : Outlet 1.6636E+01 Domain : Combustor 5.2454E+03 Domain Interface : Domain Interface 1 5.3004E-01 Domain Interface : Domain Interface 2 -5.2638E+00 Domain Interface : LowerGGI -1.9895E-01 Domain Interface : Periodic 1.1727E+01 Domain Interface : UpperGGI 1.6994E-01 ----------- Domain Imbalance : 1.8195E+03The I-Radiation imbalances reported in the CFX-Solver Output file represent the global heat flow imbalances due to radiation for all domains. Flows through domain interfaces are not included, therefore when radiation occurs in more than one connected domain the imbalance in any individual domain will be non-zero in general. However, the final Global Imbalance reported in the CFX-Solver Output file should be close to zero, indicating the convergence of a solution.
When plotting the domain-based I-Radiation imbalances for multi-domain radiation cases you should expect a non-zero value in a converged solution as noted above. The plotted domain imbalances are normalized by the magnitude of the largest flux in that domain, therefore it is not valid to sum the normalized imbalances across domains to obtain the global value.
When the Rosseland model is selected:
