OpenFOAM/C2/Creating-simple-geometry-in-OpenFOAM/English-timed
From Script | Spoken-Tutorial
| Time | Narration |
| 00:01 | Hello and welcome to the spoken tutorial on creating simple geometry in OpenFOAM. |
| 00:06 | In this tutorial, I will show you: |
| 00:08 | How to create simple geometry |
| 00:11 | How to view the geometry in paraview. |
| 00:15 | To record this tutorial,I am using: Linux Operating system Ubuntu version 10.04 OpenFOAM version 2.1.0 ParaView version 3.12.0 |
| 00:26 | The tutorials were recorded using the versions specified in previous slide. Subsequently the tutorials were edited to latest versions. To install latest system requirements go to Installation Sheet. |
| 00:30 | In CFD the Pre-processing part consists of creating geometry and meshing it. |
| 00:37 | Let us take the Lid driven cavity case of the previous tutorial as an example. |
| 00:41 | Recall the path for the earlier tutorial. |
| 00:44 | I have already opened the command terminal and entered the path for lid driven cavity. |
| 00:48 | To source the OpenFOAM version 5, type:$of5. To go to the run folder, type:$cd $FOAM_RUN. To open the cavity case directory, type:$cd tutorials/incompressible/icoFoam/cavity/cavity. To list the contents of case directory, type:$ls.
|
| 00:54 | There are three folders '0, constant' and 'system'. 'Geometry' is inside the 'polymesh' folder of 'constant'. |
| 01:11 | In the command terminal, type: cd space constant and press Enter. |
| 01:19 | Now, type "ls" and press Enter. |
| 01:21 | In this, there is another folder called as 'polyMesh'. |
| 01:26 | Now type: cd space polymesh and press Enter. |
| 01:34 | Now type "ls" and press Enter. |
| 01:39 | To list the contents of the cavity directory, type:$ls. 0 constant system. To open the system directory, type:$cd system. To list the contents of the system directory, type:$ls blockMeshDict controlDict fvSchemes fvSolution. |
| 01:45 | This contains the 'geometry' file called as 'blockMeshDict'. |
| 01:48 | Open the 'blockMeshDict' file with any editor of your choice. |
| 01:52 | In the terminal, type: gedit space blockMeshDict( Note that M and D are capital) and press Enter. |
| 02:07 | Let me drag this to the capture area. |
| 02:11 | Now minimize this. |
| 02:15 | Let me switch back to the slide. |
| 02:17 | In openfoam, the entire geometry is broken into blocks . |
| 02:21 | The blocks are numbered starting from 0 (zero) as shown in the figure. |
| 02:30 | Note that in OpenFOAM, for creating a 2D geometry you need to give an unit cell thickness value in the z-axis. |
| 02:41 | lid driven cavity is of length 1 and height 1. Minimize the slide. |
| 02:51 | On your desktop, create an empty file by right click > create document > Empty file. Name this as 'blockMeshDict'. (Note that M and D here are capital). |
| 03:10 | Open this. Now, copy the data from the original lid driven cavity 'blockMeshDict' file to the new 'blockMeshDict' file from line 0. |
| 03:21 | Scroll up line 0 upto 'convertTometers'. Copy this and paste it here. |
| 03:38 | Scroll down. Now leave some space after 'converttometers'. |
| 03:44 | Enter 1 as the geometry is in meters. Insert a semicolon and press Enter. |
| 03:52 | Again press Enter. In the file, type "vertices" and press Enter. |
| 04:01 | Insert the open bracket and press Enter. |
| 04:04 | Press the tab key. Start with point 0, insert open, close brackets, Enter. |
| 04:14 | 0 space 0 space 0 and press Enter. Again, press tab key, open close bracket . |
| 04:24 | Move towards point 1 in positive x-axis and enter 1 space 0 space 0 and press Enter. |
| 04:34 | Again press the tab key, open close bracket. Move towards point 2 in the positive x-y plane and enter 1 space 1 space 0 and press Enter. |
| 04:48 | Again press tab key, open close bracket. Enter the 3rd point in positive y-axis 0 space 1 space 0 , press Enter. |
| 05:01 | Again press the tab key. Enter the 4th point on the front face, open close bracket, 0 space 0 space 0.1 and press Enter. |
| 05:13 | Similarly, enter the other points with one unit value in the positive z- axis. |
| 05:19 | close the bracket and insert a semicolon after it. Press Enter, again press Enter. |
| 05:26 | Below vertices are the blocks. Type blocks and press Enter. Insert a open bracket and press Enter. |
| 05:39 | Let me switch back to the slides. |
| 05:41 | Note that Lid driven cavity is taken as a single block. |
| 05:46 | Let me switch back to 'blockmeshdict'. |
| 05:48 | Enter the points for the block in the clockwise sense. |
| 05:53 | We are using here hexa hedral blocks for meshing. |
| 05:56 | Now, type "hex". Leave some space. In brackets, enter 0 space 1 2 3 4 5 6 7 , again leave some space. |
| 06:15 | Note that for multiple blocks, the points will be more. |
| 06:20 | After this, enter the grid points in the x, y and z directions. |
| 06:25 | In brackets, open close brackets, enter 30 space 30 space 1. Leave some space, you can modify the grid as and when needed. |
| 06:38 | Grid point in the z-axis can be taken as one. |
| 06:44 | Now, leave some space and type "simple Grading". Leave some space, open close bracket, enter 1 space 1 space 1 . |
| 06:58 | This is the grid spacing in the x, y and z directions. Press Enter. |
| 07:05 | Insert close bracket, insert a semicolon and press Enter. |
| 07:11 | Again press Enter. Now type "edges" and press Enter. |
| 07:17 | As this is a simple geometry, edges can be kept empty. |
| 07:21 | Insert open bracket, press Enter, close the bracket. Insert a semicolon and press Enter. |
| 07:28 | Again press Enter. Below edges are the boundary conditions. |
| 07:33 | Here you need to enter the boundary names for the faces. |
| 07:37 | Type "boundary" and press Enter . |
| 07:41 | Insert an open bracket and press Enter. |
| 07:45 | Now, let me switch back to the slides. |
| 07:48 | In the geometry, the upper wall is moving and other three walls are fixed. |
| 07:53 | The front and back faces are named as 'empty' as this is a 2D problem. |
| 08:01 | Open the new 'blockMeshDict' file again. |
| 08:04 | In boundary, put the name of the patch as 'moving wall' . Press Enter. |
| 08:16 | Now, insert a open curly bracket and press Enter. |
| 08:20 | Now, enter the type for the moving wall , enter "type" space "wall". |
| 08:28 | Insert a semicolon and press Enter. |
| 08:33 | Now, faces, now press Enter, insert open bracket and press Enter. Press the tab key, open close bracket. |
| 08:47 | In this bracket, enter the points for faces. |
| 08:51 | Let me switch back to the slide. |
| 08:54 | Note that the order of the points should be in such a way that the thumb should be normal to the face |
| 09:01 | and fingers making a curl as shown in the figure. |
| 09:06 | The curl can be clockwise or anti-clockwise. |
| 09:09 | Also note that the points should match with the points inserted in vertices. |
| 09:14 | Now, let me switch back to the new 'blockMeshDict' file. |
| 09:18 | Now in the faces, enter 3 space 7 space 6 space 2. |
| 09:28 | Let me switch back to the slide. These are the points for the moving wall 3, 7, 6, 2. |
| 09:35 | Minimize this. Note that you can start from any point on that face. Now press Enter. |
| 09:44 | Close the bracket. Again press Enter. Close the curly bracket. |
| 09:55 | Another note: we need to enter a semi colon after you insert the points for faces. Now after the curly brackets, press Enter, again press Enter. |
| 10:01 | Now, similarly enter boundary condition and faces for the fixed walls. |
| 10:06 | Being a 2D problem the type of boundary for the front and back faces can be kept as empty. |
| 10:13 | Refer to the figure in the slide. For entering the points, minimize this. |
| 10:19 | Insert the closed brackets, put a semicolon and press Enter, again press Enter. |
| 10:26 | Now type "mergePatchPairs" and press Enter. |
| 10:32 | Since there are no patches to be merged, it can be kept empty. |
| 10:35 | Insert open close brackets. Insert a semicolon and press Enter. |
| 10:41 | We are done with creating the 'blockMeshDict' file. Save this. |
| 10:46 | The complete 'blockMeshDict' file is as shown here. |
| 10:54 | Close both the 'blockMeshDict' files. |
| 10:56 | Note that the command terminal will not work until the blockMeshDict file is closed. |
| 11:01 | Switch back to the terminal. Now, type cd space (dot) (dot) twice to return back to the 'cavity' folder. Now Mesh the geometry. |
| 11:12 | To do this, on the terminal, type: "blockMesh" and press Enter. |
| 11:20 | Now, view the geometry by typing on the command terminal paraFoam and press Enter. |
| 11:27 | This will open the ParaView window. |
| 11:30 | Now, on the left hand side, click Apply on object inspector menu. Thus, you can see the geometry. |
| 11:39 | Now, let me switch back to the slides. |
| 11:43 | In this tutorial, we learnt: |
| 11:45 | Creating a simple geometry in OpenFOAM |
| 11:49 | Viewing the geometry in Paraview . |
| 11:52 | This brings us to the end of the tutorial. |
| 11:56 | As an Assignment- |
| 11:58 | Change the dimensions of the lid driven cavity, change the grid size to 50 50 1 and view the geometry in paraView. |
| 12:08 | Watch the video available at this URL: [1] |
| 12:11 | It summarizes the Spoken Tutorial project. |
| 12:13 | If you do not have a good bandwidth, you can download and watch it. |
| 12:18 | The Spoken Tutorial project team: |
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contact@spoken-tutorial.org |
| 12:48 | Spoken Tutorial project is part of the Talk to a Teacher project. |
| 12:51 | It is supported by the National Mission on Education through ICT, MHRD, Government of India. |
| 12:57 | More information on this mission is available at the following URL: |
| 13:02 | This is Rahul Joshi from IIT Bombay, signing off. Thanks for joining. |
Contributors and Content Editors
DeepaVedartham, Gaurav, PoojaMoolya, Pratik kamble, Sandhya.np14, Sneha
