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
Discretizer Manual Release date 09/01/10 Side 2 of 13 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
Discretizer Manual Release date 09/01/10 Side 3 of 13 1. Preface 1.1 Introduction Discretizer 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) openfoam 16 installation OpenFOAM 1.6 install cookbook Windows Not supported Not supported 1.3 Installing Discretizer Operating System Binary Compiling Linux discretizer 32and64bit Windows Starting Discretizer: Start a Terminal Change to the discretizer Directory Start Discretizer by typing./discretizer32.sh or./discretizer64.sh 1.4 Conventions The 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
Discretizer Manual Release date 09/01/10 Side 4 of 13 1.5 Main Window 1 2 4 3 Picture 1: The Main Window of Discretizer 5 1 Pull down 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 pop up 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
Discretizer Manual Release date 09/01/10 Side 5 of 13 2. Example 2.1 Step The 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
Discretizer Manual Release date 09/01/10 Side 6 of 13 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
Discretizer Manual Release date 09/01/10 Side 7 of 13 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
Discretizer Manual Release date 09/01/10 Side 8 of 13 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
Discretizer Manual Release date 09/01/10 Side 9 of 13 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
Discretizer Manual Release date 09/01/10 Side 10 of 13 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
Discretizer Manual Release date 09/01/10 Side 11 of 13 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
Discretizer Manual Release date 09/01/10 Side 12 of 13 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
Discretizer Manual Release date 09/01/10 Side 13 of 13 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