Chapter 13 |
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MESH REPLACEMENT |
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Setting Up Mesh Replacement in pro-STAR |
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In the Select panel, click Multiple Meshes to |
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open the Multiple meshes panel |
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Click the ellipsis (...) button next to the |
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Subdirectory box |
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In the file browser, select dense and then |
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click OK to specify the directory where the |
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replacement mesh is located |
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Click Add in the upper half of the panel to |
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specify the dense mesh in the Meshes box |
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Set Angle to 340 and Mesh to 1 to specify the |
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crank angle and mesh for the first mesh |
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replacement |
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Click Add in the lower half of the panel to |
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enable the first mesh replacement |
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Define the remaining mesh replacements |
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using the following settings: |
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Angle |
Mesh |
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380 |
0 |
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700 |
1 |
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740 |
0 |
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•Click Write to create the MULTIMESH.BAT batch file and merge the mvmesh.sh files of both models into a single file. A backup of the original mvmesh.sh is created called mvmesh.sh.original.
The set-up within the coarse model is now complete.
•In the Select panel, click Write Data
•In the Write Tool, enter save_es-ice.coarse and click Save
•Close es-ice
Setting Up Mesh Replacement in pro-STAR
The pro-STAR set-up for a mesh-replacement simulation is slightly different from a normal simulation as two or more models are defined simultaneously. You must therefore ensure that the pro-STAR set-up in your own cases adheres to the following guidelines:
•The initial and boundary conditions, combustion models and any tracers defined within the es-ice Star Controls panel must be identical to the settings in pro-STAR
•Additional physics settings defined within pro-STAR are read from the problem file present in the working directory. These include settings for thermophysical, spray and/or liquid film models. In this example, both the coarse and dense model files have been set up correctly.
•Analysis and run-time controls in the model files do not need to be identical. These settings include under-relaxation, time-step size, residual tolerances, output frequency and backup frequency. In this example, the time-step
Version 4.20 |
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controls remain as specified in es-ice but other common settings are applied to the analysis output controls for both models. The under-relaxation for pressure correction is set to 0.5.
To read the es-ice model files:
•Launch pro-STAR from the directory containing the master model file (save_es-ice.4-final)
•Enter the command below (it may take some time to complete):
IFILE, MULTIMESH.BAT
This command resizes pro-STAR memory, imports the models and creates an events file.
•Enter the following commands to display the coarse mesh:
CSET, ALL CPLOT
Setting up the coarse model
Set the under-relaxation factor as shown in Figure 13-7.
•In the Analysis Controls > Solution Method panel, set Under Relaxation for Pressure Correction to 0.5
•Click Apply
Figure 13-7 Under-relaxation for pressure correction
Specify the output control settings as shown in Figure 13-8.
•Go to panel Analysis Controls > Analysis Output
•In the Post tab, set Output Frequency to 10 and Backup Frequency to 300
•Click Apply
•In the Transient tab, set Start at time to 320 degrees CA and Output interval to
5 degrees CA
•Select any flow variables that you wish to post-process
•Click Apply
Chapter 13 |
MESH REPLACEMENT |
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Setting Up Mesh Replacement in pro-STAR |
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Figure 13-8 Post and transient analysis output settings
Setting up the dense model
Reading the MULTIMESH.BAT file into pro-STAR defines the dense model location.
•Enter the following command to switch to the dense model:
MREPLACE, SWITCH, 1
•Enter the following commands to display the dense model:
CSET, ALL
CPLOT
The parameter that is set to 1 in the previous command selects the dense model. If you wish to switch back, the coarse model can be selected using 0 as the parameter value.
Having switched to the dense model, the same settings are now used for under-relaxation and output controls. The previous panels can be used again to verify these operations.
Set the under-relaxation factor.
•In the Analysis Controls > Solution Method panel, set Under Relaxation for Pressure Correction to 0.5
•Click Apply
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Specify the output control settings.
•Go to panel Analysis Controls > Analysis Output
•In the Post tab, set Output Frequency to 10 and Backup Frequency to 300
•Click Apply
•In the Transient tab, set Starting at time to 320 degrees CA and Output interval to 5 degrees CA
•Select any flow variables that you wish to post-process
•Click Apply
When the pro-STAR set-up is complete, write the geometry and problem files for both models. This action creates .ccmg and .prob files in the relevant directories for both.
•Enter the following commands:
MREPLACE, GEOMWRITE, 0.001, CCM
MREPLACE, PROBLEMWRITE
The pro-STAR set-up is now complete, so:
•Click Quit > Save & Quit to close pro-STAR
The solver can now be run in the usual manner, as described in Chapter 8 of this volume.