The main issue during a multiphysics analysis is whether the model is converging or not, and how easily it is converging. Once the iterations begin, monitoring this text will help the analyst decide if the analysis needs to be stopped to change some parameters.
The columns in convergence history are as follows (see Figures 1 and 2). The transient and steady coupled analysis log files are similar but slightly different.
01 For Buoyancy Force :: LC No. = 2 Total No. of Intvs = 3 02 ------------------------------------------------------------------------ 03 Current No. Load Turbulent Max. No. Convergence Tolerance 04 Intv No. Steps Multiplier Model Iters (Temp.) (Vel.) 05 1 1 1.00e-002 off 500 1.00e-003 1.00e-003 06 ------------------------------------------------------------------------ 07 Intv No. Step No. Iter. No. Euc. Norm (Vel.) Euc. Norm (Temp.) 08 1 1 1 Rlx = 0.200 Rlx = 0.200 09 1 1 2 1.224e-002 2.633e-002 10 1 1 3 1.411e-002 2.093e-002 11 1 1 4 1.542e-002 1.656e-002 12 1 1 5 1.578e-002 1.304e-002 {text removed for brevity} 13 1 1 22 1.253e-003 4.412e-004 14 1 1 23 1.125e-003 3.893e-004 15 1 1 24 1.020e-003 3.449e-004 16 1 1 25 9.316e-004 3.068e-004 17 >> Current elapsed time = 1.333 minutes 18 19 For Buoyancy Force :: LC No. = 2 Total No. of Intvs = 3 20 ------------------------------------------------------------------------ 21 Current No. Load Turbulent Max. No. Convergence Tolerance 22 Intv No. Steps Multiplier Model Iters (Temp.) (Vel.) 23 2 1 1.00e-001 off 500 1.00e-003 1.00e-003 24 ------------------------------------------------------------------------ 25 Intv No. Step No. Iter. No. Euc. Norm (Vel.) Euc. Norm (Temp.) 26 2 1 1 Rlx = 0.200 Rlx = 0.200 27 2 1 2 2.876e-001 2.165e-002 |
| Figure 1: Sample Text From Steady Log File (see the .LFC file in the design scenario folder) Line numbers were added to help with the following description. |
With the previous explanation in mind, the sample log file in Figure 1 can be interpreted as follows:
01 For Buoyancy Force :: Total No. of Intvs = 3 02 ------------------------------------------------------------------------ 03 Current No. Load Turbulent Max. No. Convergence Tolerance 04 Intv No. Steps Multiplier Model Iters (Temp.) (Vel.) 05 1 1 1.00e-002 off 500 1.00e-003 1.00e-003 06 ------------------------------------------------------------------------ 07 Euc. Norm Euc. Norm 08 Intv Step Time Percent DT Iter Vel. Temp. 09 1 1 1.000e+000 33.33 1.000e+000 1 Rlx = 0.20 Rlx = 0.80 10 1 1 1.000e+000 33.33 1.000e+000 2 7.071e-001 2.618e+000 11 1 1 1.000e+000 33.33 1.000e+000 3 2.382e-001 5.237e-001 12 1 1 1.000e+000 33.33 1.000e+000 4 1.033e-001 1.047e-001 13 1 1 1.000e+000 33.33 1.000e+000 5 4.922e-002 2.095e-002 14 1 1 1.000e+000 33.33 1.000e+000 6 2.487e-002 4.189e-003 15 1 1 1.000e+000 33.33 1.000e+000 7 1.315e-002 8.379e-004 16 1 1 1.000e+000 33.33 1.000e+000 8 7.191e-003 1.676e-004 17 1 1 1.000e+000 33.33 1.000e+000 9 4.023e-003 3.352e-005 18 1 1 1.000e+000 33.33 1.000e+000 10 2.284e-003 6.703e-006 19 1 1 1.000e+000 33.33 1.000e+000 11 1.308e-003 1.341e-006 20 1 1 1.000e+000 33.33 1.000e+000 12 8.335e-004 2.681e-007 21 >> Current elapsed time = 0.167 minutes 22 23 For Buoyancy Force :: Total No. of Intvs = 3 24 ------------------------------------------------------------------------ 25 Current No. Load Turbulent Max. No. Convergence Tolerance 26 Intv No. Steps Multiplier Model Iters (Temp.) (Vel.) 27 2 1 1.00e-001 off 500 1.00e-003 1.00e-003 28 ------------------------------------------------------------------------ 29 Euc. Norm Euc. Norm 30 Intv Step Time Percent DT Iter Vel. Temp. 31 2 1 2.000e+000 66.67 1.000e+000 1 Rlx = 0.20 Rlx = 0.60 32 2 1 2.000e+000 66.67 1.000e+000 2 3.938e-001 4.280e+000 33 2 1 2.000e+000 66.67 1.000e+000 3 2.109e-001 1.373e+000 |
| Figure 2: Sample Text From Transient Log File (see .LFT file in the design scenario folder) Line numbers were added to help with the following description. |
With the above explanation in mind, the sample log file in Figure 2 can be interpreted as follows:
Analysis Runs, but no text appears in the statistics window or only a few header lines appear
Cause 1: For a transient analysis, MPICH is not registered. (Another indication of this problem is that the Task Manager does not show ssap11LD as a running process.)
Action 1: Run mpiexec.exe ¬register, where mpiexec.exe is located in the MPICH2\bin folder where the MPICH software was installed. Your are prompted for the username and password. This action can be done with the Windows Start: Run command, or from a command window set to the bin folder.
Cause 2: An error occurred in either the heat transfer calculation or the fluid flow calculation which halted the analysis.
Action 2: Use the Stop button to stop the analysis and then close the Analysis window, if necessary. Then use the Report environment to view the log and summary files from the heat transfer and fluid flow analyses.
Unable to run mpiexec.
Cause: Transient Coupled Fluid Flow and Thermal uses MPICH2 to pass information between the fluid flow processor and the thermal processor. This free software needs to be installed before running the analysis.
Action: Install the MPICH2 software. Refer to the page Installation Guide: Windows Installation: MPICH on Windows for instructions.