discretizer-manual
TRANSCRIPT
Discretizer Manual – Release date 09/01/10 Side 1 of 13
A Guide to the free mesh program Discretizer with OpenFOAM for CFD (Computational
Fluid Dynamics)
Homepage: http://www.discretizer.org/Creator of Discretizer: Bjorn Bergqvist
Manual Author: Gerhard Gruber
Program and Manual under the GPL license v3 or later
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Table of Contents
1. Preface
1.1 Introduction
1.2 Installing OpenFOAM
1.3 Installing Discretizer
1.4 Conventions
1.5 Main Window
2. Example
2.1 Step
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1. Preface
1.1 IntroductionDiscretizer is an interactive preprocessing geometry and mesh creation tool.
It will create geometry and meshes for three dimensional flow simulations (CFD).
It is optimized to work with OpenFOAM as solver and the included post processing program ParaFOAM .
1.2 Installing OpenFOAM
Operating System Binary Compiling
Ubuntu (9.04) openfoam16installation OpenFOAM1.6 install cookbook
Windows Not supported Not supported
1.3 Installing Discretizer
Operating System Binary Compiling
Linux discretizer32and64bit
Windows
Starting Discretizer:
– Start a Terminal
– Change to the “discretizer” Directory
– Start Discretizer by typing “./discretizer32.sh” or “./discretizer64.sh”
1.4 ConventionsThe Discretizer Manual use the following style conventions.
Menu selections, to take orders, are shown in bold. For example: File New→
Tips have cursive style. For example: Tip: Press the STRG Key
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1.5 Main Window
Picture 1: The Main Window of Discretizer
1 Pulldown menu bar
offers the main commands of Discretizer, explanation in chapter 2
Tip: BC is the short cut of Boundary Conditions
2 Icon bar
each picture shows his function in the status line or popup help when you put the mouse cursor over it
3 Item with attribute chart
each command for the geometry is shown in this chart
Tip: each command can be modified by selecting it's item, pressing the right mouse button and select properties
4 Geometry window
shows the geometry model
5 Status line
shows system output
1
2
3
4
5
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2. Example
2.1 StepThe Step shows how to create geometry models with Discretizer and make a complete simulation with OpenFOAM.
Tip: The complete geometry model is saved in “discretizer/discretizer/svn/test/t19_step.dtz”
1. Create Point→
Press the OK Button
Select the created Point
Tip: it can be also selected by selecting the row of the point in the Item chart
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2. Create Cube→
Enter the cube attributes
Tip: “x,y,z mesh points” defines the number of mesh cells
Tip: you can modify the attributes by selecting the row of the cube in the item chart, pressing the right mouse button and selecting “Properties”
Reset the View by pressing the Reset Button in the Icon bar
Tip: The model can be
rotated by pressing the left mouse Button and moving the mouse inside the geometry window
it can be scaled by scrolling with the mouse wheel
and you can drag it by pressing the right mouse Button
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3. Select the right front face of the cube and choose Create Cube→
Enter the cube attributes
Press the OK Button
Tip: the Create Cube dialogue can also be started by selecting the face, pressing the right mouse button and selecting “Create Cube”
4. Select the upper face of the second cube and choose Create Cube→
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5. Select the left front face of the first cube and choose BC Create Inlet→
Enter the “Velocity Magnitude” and the Direction, 1 is “yes” 0 is “no”.
Press the OK Button
6. Select the right front face of the second cube and select the right front face of the third cube, choose BC Create Outlet→
Enter Pressure
Press the OK Button
Tip: at least one velocity inlet and one pressure outlet is recommended for a simulation
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7. File Run Dialog→
In the Field “Case Info:” you can define some properties
Work Dir: is the directory where the “Case” will be stored
Case Name: Defines the name of this simulation, enter “step”
OpenFOAM Solver: is the solver used by OpenFOAM
Scale Factor: is the scale factor the model will be transformed
(measures in Discretizer are in mm, measures in OpenFOAM are in m)
0.001 don't has to be changed
Tip: the Field “Initial conditions” don't has to be changed because they are defined with the Boundary Conditions at the inlet (see Point 5)
Start the simulation by pressing the “Write and Run” Button
Tip: have a look at the Terminal Window, some output with “Time = “ and data shows the progress of the calculation
The time how long the calculation takes depends on the number of mesh cells you have defined and the power of your computer
If “End” is shown the calculation has finished
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8. The result of the simulation can be shown by pressing the “Paraview” Button
Actually nothing is shown
At first press the “Last Frame” Button, or Animation Last frame→
Now press the highlighted green “Apply” Button
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Choose “U” for velocity from the Icon bar
Tip: The model can be
rotated by pressing the left mouse Button and moving the mouse inside the geometry window
it can be scaled by scrolling with the mouse wheel or pressing the right mouse Button and moving the mouse inside the window up or down
and you can drag it by pressing the mouse wheel
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9. Press the “Clip” Button from the Icon bar, press the “Z Normal” Button and select “Inside Out”
Press the “Display” Tab, press the “Edir Color Map...” Button, Press the “Color Legend” Tab and select “Show Color Legend”
Now you can see the velocity range from the step
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10. Choose “p” for pressure from the Icon bar
Press the “Display” Tab, press the “Edir Color Map...” Button, Press the “Color Legend” Tab and select “Show Color Legend”
Now you can see the pressure range from the step