OpenFOAM/C2/Creating-simple-geometry-in-OpenFOAM/English-timed
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Revision as of 16:07, 21 June 2016 by Sandhya.np14 (Talk | contribs)
| 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, |
| 00:16 | I am using:
|
| 00:27 | In CFD the Pre-processing part consists of creating geometry and meshing it. |
| 00:33 | Let us take the Lid driven cavity case of the previous tutorial as an example. |
| 00:38 | Recall the path for the earlier tutorial, |
| 00:40 | I have already opened the command terminal and entered the path for lid driven cavity. |
| 00:48 | There are three folders '0, constant' and 'system'. 'Geometry' is inside the 'polymesh' folder of 'constant'. |
| 00:55 | In the command terminal, type: cd space constant and press Enter. |
| 01:03 | Now, type "ls" and press Enter. |
| 01:06 | In this, there is another folder called as 'polymesh'. |
| 01:10 | Now type: cd space polymesh and press Enter. |
| 01:18 | Now type "ls" and press Enter. |
| 01:22 | This contains the 'geometry' file called as 'blockMeshDict'. |
| 01:26 | Open the 'blockMeshDict' file with any editor of your choice. |
| 01:30 | In the terminal, type: gedit space blockMeshDict( Note that M and D are capital) and press Enter. |
| 01:45 | Let me drag this to the capture area. |
| 01:49 | Now minimize this. |
| 01:53 | Let me switch back to the slides. |
| 01:55 | In openfoam, the entire geometry is broken into blocks . |
| 01:59 | The blocks are numbered starting from 0 as shown in the figure., |
| 02:08 | Note that in OpenFOAM, for creating a 2D geometry you need to give an unit cell thickness value in the z-axis. |
| 02:19 | lid driven cavity is of length 1 and height 1. Minimize the slide. |
| 02:29 | 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). |
| 02:48 | Open this. Now Copy the data from the original lid driven cavity 'blockMeshDict' file to the new 'blockMeshDict' file from line 0. |
| 02:59 | Scroll up line 0 upto 'convertTometers'. Copy this and paste it here. |
| 03:15 | Scroll down. Now leave some space after 'converttometers'. |
| 03:21 | Enter 1 as the geometry is in meters. Insert a semicolon and press Enter. |
| 03:30 | Again press Enter. In the file, type "vertices" and press Enter. |
| 03:39 | Insert the open bracket and press Enter. |
| 03:43 | Press the tab key. Start with point 0, insert open, close brackets, Enter. |
| 03:52 | 0 space 0 space 0 and press Enter. Again, press tab key, open close bracket . |
| 04:02 | Move towards point 1 in positive x-axis and enter 1 space 0 space 0 and press Enter. |
| 04:12 | Again press tab key, open close bracket. Move towards point 2 in positive x-y plane and enter 1 space 1 space 0 and press Enter. |
| 04:26 | Again press tab key, open close bracket. Enter the 3rd point in positive y-axis 0 space 1 space 0 , press Enter. |
| 04:39 | Again press tab key. Enter the 4th point on the front face, open close bracket 0 space 0 space 0.1 and press Enter. |
| 04:51 | Similarly, enter the other points with one unit value in the positive z- axis. |
| 04:56 | close the bracket and insert a semicolon after it. Press Enter, again press Enter. |
| 05:03 | Below vertices are the blocks. Type blocks and press Enter. Insert a Open bracket and press Enter. |
| 05:16 | Let me switch back to the slides. |
| 05:19 | Note that Lid driven cavity is taken as a single block. |
| 05:24 | Let me switch back to 'blockmeshdict'. |
| 05:27 | Enter the points for the blocks in the clockwise sense. |
| 05:31 | We are using here hexa hedal blocks for meshing. |
| 05:34 | Now, type "hex". Leave some space. In brackets, enter 0 space 1 2 3 4 5 6 7 , again leave some space. |
| 05:53 | Note that for multiple blocks, the points will be more. |
| 05:58 | After this, enter the grid points in the x, y and z directions. |
| 06:02 | In brackets open close brakets enter 30 space 30 space 1 leave some space , you can modify the grid as an when needed |
| 06:16 | Grid point in z-axis can be taken as one |
| 06:22 | Now leave some space and type simple grading leave some space open close bracket enter 1 space 1 space 1 |
| 06:36 | This is the grid spacing in the x y and z direction. Press Enter |
| 06:43 | Insert close bracket, insert a semicolon and press Enter |
| 06:48 | Again press Enter. Now type edges, and press Enter |
| 06:55 | As this is a simple geometry edges can be kept empty |
| 07:00 | Insert open bracket press Enter, close the bracket ,insert a semicolon and press Enter |
| 07:07 | Again press Enter. Below edges are the boundary conditions. |
| 07:11 | Here you need to enter the boundary name for the faces |
| 07:15 | Type boundary and press Enter . |
| 07:19 | insert a open bracket and press Enter |
| 07:23 | Now let me switch back to the slides |
| 07:26 | In the geometry the upper wall is moving and other three walls are fixed. |
| 07:31 | The front and back faces are named as empty as this is a 2D problem |
| 07:39 | Open the new blockMeshDict file again |
| 07:42 | In boundary put the name of the patch as moving wall . Press Enter |
| 07:51 | Now Insert a open curly bracket and press Enter |
| 07:56 | Now enter the type for the moving wall , enter type space wall |
| 08:06 | insert a semicolon and press Enter |
| 08:09 | Now insert open bracket, and press Enter. Press the tab key. Open close bracket. |
| 08:20 | In this bracket enter the pointfor for faces |
| 08:24 | Let me switch to the slide |
| 08:27 | Note that order of the points should be in such a way that the thumb should be normal to the face |
| 08:34 | And fingers making a curl as shown in the figure . |
| 08:39 | The curl can be clockwise or anti- clockwise |
| 08:43 | Also note that the points should match with the points inserted in vertices |
| 08:48 | Now let me switch back to the new blockmeshdict file . |
| 08:52 | Now in the faces enter 3 space 7 space 6 space 2. |
| 09:01 | Let me switch back to the slide. These are the point for the moving wall 3,7,6,2. |
| 09:09 | Minimise this. Note that you can start from any point on that face. Now press Enter |
| 09:17 | Close the bracket again press Enter. Close the curly bracket. |
| 09:22 | Another note we need to enter a semi- colon, after you insert the points, a faces now after the curly brackets, press Enter again press Enter |
| 09:35 | Now similarly enter boundary condition and faces for the fixed wall |
| 09:40 | Being a 2D problem the type of boundary for front and back face can be kept as empty. |
| 09:46 | Refer to the figure in the slide. For entering the points. Minimise this |
| 09:52 | Insert the closed brackets, put a semicolon and press Enter, again press Enter |
| 09:59 | Now type mergePatchPairs and press Enter |
| 10:04 | Since their are no patches to merge it can be kept empty |
| 10:08 | Insert open close bracket. Insert a semi-colon and press Enter |
| 10:14 | We are done with creating the blockmeshdict file. Save this |
| 10:18 | The complete blockMeshDict file is as shown here. |
| 10:26 | Close both the blockMeshDict files |
| 10:29 | Note that the command terminal will not work until blockMeshDict file is closed |
| 10:35 | Switch back to the terminal. Now type cd (dot) (dot) twice to return back to the cavity folder. Now Mesh the geometry |
| 10:45 | To do this in a terminal type: blockMesh and press Enter |
| 10:53 | Now View the geometry by typing in the command terminal paraFoam and press Enter |
| 10:59 | This will open the ParaView window |
| 11:03 | Now On the left hand side click Apply on object inspector menu thus you can see the geometry. |
| 11:13 | Now let me switch back to the slides |
| 11:16 | In this tutorial we learnt: |
| 11:18 | Creating a simple geometry in OpenFOAM |
| 11:22 | Viewing the geometry in Paraview |
| 11:25 | This brings us to the end of the tutorial |
| 11:29 | As an Assignment |
| 11:31 | Change the direction of lid driven cavity ,Change the grid size to 50 50 1and View the geometry in paraview |
| 11:41 | Watch the video available at this URL: http://spoken-tutorial.org/What_is_a_Spoken_Tutorial |
| 11:44 | It summarizes the Spoken Tutorial project. |
| 11:46 | If you do not have good bandwidth, you can download and watch it. |
| 11:51 | The Spoken Tutorial Project Team |
| 11:53 | -Conducts workshops using spoken tutorials |
| 11:55 | -Gives certificates to those who pass an online test |
| 11:59 | -For more details, please write to contact@spoken-tutorial.org |
| 12:05 | Spoken Tutorial project is part of Talk to a Teacher project, |
| 12:09 | It is supported by the National Mission on Education through ICT, MHRD, Government of India. |
| 12:15 | More information on the same is available at the following URL link http://spoken-tutorial.org/NMEICT-Intro |
| 12:19 | This is Rahul Joshi from IIT BOMBAY signing off.Thanks for joining. |
Contributors and Content Editors
DeepaVedartham, Gaurav, PoojaMoolya, Pratik kamble, Sandhya.np14, Sneha
