OpenFOAM/C2/Creating-simple-geometry-in-OpenFOAM/English
Title of script: Creating simple geometry in OpenFOAM
Author: Rahul Ashok Joshi
Keywords: Video Tutorial,Computational Fluid Dynamics (CFD),OpenFOAM geometry
| Visual Cue | Narration |
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| Slide 1 |
Hello and welcome to the spoken tutorial on creating a simple geometry in OpenFOAM |
| Slide 2: Learning Objective | In this tutorial I will show you
How to create a simple geometry How to view geometry in paraview |
| Slide 3: System Requirement | To record this tutorial
I am using GNU / Linux Operating system Ubuntu 10.04 OpenFOAM version 2.1.0 ParaView version 3.12.0 |
| Open the path for lid driven cavity as given in the installation tutorial |
. In CFD the Pre-processing part consists of creating geometry and meshing it. Let us take the Lid driven cavity case of the previous tutorial as an example. Recall the path for the earlier tutorial, I have already opened the command terminal and entered the path for lid driven cavity There are three folders 0,constant,and system Geometry is inside the polymesh folder of constant. In the command terminal type cd constant and press enter Type ls and press enter In this there is another folder called as polymesh type cd polymesh and press enter type ls and press enter This contains the geometry file called as blockMeshDict Open the blockMeshDict file with any editor of your choice In the terminal type gedit blockMeshDict and press enter
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Minimise the blockMeshDict file Let me switch back to the slides In openfoam the entire geometry is broken into blocks The blocks are numbered starting from 0 as shown in the figure Note that in OpenFOAM for creating a 2D geometry you need to give a a unit cell thickness value in the z-axis. Lid driven cavity is of length 1 and height 1, minimise the slide On your desktop create an empty file by right click > create document > Empty file and name it as blockMeshDict. Copy the data from the original lid driven cavity blockMeshDict file to the new blockMeshDict file form line 0 to convertTometers. In the file type vertices and press enter Put the open brackets and in the next line Start with 0 point, in brackets enter(0 space 0 space 0) and press enter move towards the point 1 in positive x-axis and enter (1 space 0 space 0) and press enter move towards point 2 in positive x-y plane and enter (1 space 1 space 0) and press enter enter the 3 point in positive y axis (0 space 1 space 0 ) and press enter enter 4 point (1 space 0 space 1) on the front face and press enter Similarly enter the other points with one unit value in the positive z -axis close the bracket and insert a semicolon after it. Below vertices are the blocks Insert a Open bracket and press enter Note that, Lid driven cavity is taken as a single block Enter the points for the blocks in a clockwise sense in brackets enter ( 0 put space after each point and enter 1 2 3 4 5 6 7 ) For multiple blocks the points will be more. After this enter the grid points in the x,y,and z directions In brackets enter (30 space 30 space 1) ,you can modify the grid when needed Grid point in z-axis can be kept as one Leave a space and in brackets enter the simple grading for the mesh (1 space 1 space 1) Close the bracket and insert a semicolon and press enter | |
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Now type edges,as this is a simple geometry edges can be kept empty Insert open and closed bracket ,put a semicolon and press enter Below edges are the boundary conditions. Here you need to enter the boundary name for the faces Type boundary and in the next line and press enter insert a open bracket and press enter Let me switch back to slides In the geometry the upper wall is moving and other three walls are fixed. The front and back faces are termed as empty as this is a 2D problem Open the New blockMeshDict file again In boundary put the name of the patch as moving wall Insert a open curly bracket Enter type for the moving wall as wall and insert a semicolon. After this in brackets enter the points for face. Let me switch to slides Note that order the points in such a way that the thumb should be normal to that face And fingers make a clockwise curl as shown in the figure Also note that the point should match with the points inserted in vertices Enter the face points as (3 space 7 space 6 space 2) as shown in the figure and Note : you can start from any point of that face. Insert a curly brackets and put a semicolon. Similarly enter boundary condition and faces for the fixed wall Being a 2D problem the type of boundary for front and back face can be kept empty. Insert open-closed brackets and put a semicolon. We are done with creating the blockMeshDict file. The complete blockMeshDict file is as shown here.
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Close the original blockMeshDict file Note that command terminal will not work until blockMeshDict file is closed type cd (dot) (dot) twice to return to the cavity folder Mesh the geometry in terminal type: blockMesh and press enter
On the left hand side click Apply on object inspector menu.
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| Summary |
In this tutorial we learnt: Creating a simple geometry in OpenFOAM Viewed the geometry in Paraview This brings us to the end of the tutorial |
| Slide 7 | Assignment
Change the geometry parameters : Enter the grid points as (40 40 1) and (50 50 1). View the geometry in paraview |
| Slide 9:About Spoken Tuitorial |
Watch the video available at this URL: http://spoken-tutorial.org/What_is_a_Spoken_Tutorial It summarizes the Spoken Tutorial project. If you do not have good bandwidth, you can download and watch it.
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| Slide 10: About spoken tutorial |
The Spoken Tutorial Project Team -Conducts workshops using spoken tutorials -Gives certificates to those who pass an online test -For more details, please write to contact@spoken-tutorial.org |
| Slide 11:Acknowledgement |
Spoken Tutorials are part of Talk to a Teacher project, It is supported by the National Mission on Education through ICT, MHRD, Government of India. This project is coordinated by http://spoken-tutorial More information on the same is available at the following URL link http://spoken-tutorial.org/NMEICT-Intro |
| About the contributor | This is Rahul Joshi from IIT BOMBAY signing off.
Thanks for joining. |
