View source for OpenFOAM/C2/Creating-simple-geometry-in-OpenFOAM/English-timed


{| border=1
|| '''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: 

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| 00:08
|* How to create '''simple geometry''' 

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| 00:11
|* How to view the geometry in '''paraview'''.

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| 00:15
| To record this tutorial, 

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| 00:16
| I am using:
* '''Linux Operating system Ubuntu''' version 10.04 
* '''OpenFOAM''' version 2.1.0 
* '''ParaView''' version 3.12.0 
|-
| 00:27
| In '''CFD''' the '''Pre-processing''' part consists of  creating geometry and '''mesh'''ing it. 

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| 00:33
| Let us take the '''Lid driven cavity''' case of the previous tutorial as an example. 

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| 00:38
| Recall the '''path''' for  the earlier tutorial, 

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| 00:40
| I have already opened the '''command terminal''' and entered  the '''path''' for '''lid driven cavity'''. 

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|  00:48
| There are three folders '0, constant' and 'system'. 'Geometry' is inside the 'polymesh' folder of 'constant'.

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| 00:55
| In the command terminal, type: '''cd space constant''' and press '''Enter'''.

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|  01:03
| Now, type "ls" and press '''Enter'''.

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| 01:06
| In this, there is another folder called as 'polymesh'. 

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| 01:10
|Now type: '''cd space polymesh''' and press '''Enter'''.

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| 01:18
|Now type "ls" and press '''Enter'''.

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| 01:22
| This contains the 'geometry' file called as 'blockMeshDict'.

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| 01:26
| Open the 'blockMeshDict' file with any '''editor''' of your choice. 

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| 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.

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| 01:49
|Now minimize this. 

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|  01:53
|  Let me switch back to the '''slide'''s. 

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|  01:55
| In '''openfoam''', the entire '''geometry''' is broken into '''blocks '''.

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|  01:59
|  The blocks are numbered starting from''' 0 '''as shown in the figure., 

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| 02:08
| Note that in '''OpenFOAM''', for creating a '''2D geometry''' you need to give an ''' unit cell thickness value''' in the '''z-axis'''.

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| 02:19
| '''lid driven cavity''' is of length 1 and height 1.  Minimize the slide. 

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| 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).

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|  02:48
| Open this. Now Copy the data from the original '''lid driven cavity''' 'blockMeshDict' file to the new 'blockMeshDict' file from line 0.

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|  02:59
| Scroll up line 0 upto 'convertTometers'. Copy this and '''paste''' it here. 

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|  03:15
| Scroll down. Now leave some space after 'converttometers'.

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|  03:21
|  Enter 1 as the geometry is in meters. Insert a semicolon and press  '''Enter'''.

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|  03:30
|Again press  '''Enter'''. In the file, type "vertices" and press  '''Enter'''.

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|   03:39
| Insert the open bracket and press  '''Enter'''.

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|   03:43
| Press the tab key. Start with point 0, insert open, close brackets,   '''Enter'''.

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| 03:52
| '''0 space 0 space 0 '''and press '''Enter'''. Again, press tab key, open close bracket .

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|  04:02
|   Move towards point 1 in positive x-axis and enter ''' 1 space 0 space 0''' and press  '''Enter'''.

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|  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'''.

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|  04:26
|Again press tab key, open close bracket. Enter the 3rd point in positive y-axis '''0 space 1 space 0 ''',  press  '''Enter'''.

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| 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'''.

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|  04:51
| Similarly, enter the other points with one unit value in the positive z- axis. 

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| 04:56
| close the bracket and insert a semicolon after it. Press  '''Enter''', again press '''Enter'''.

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| 05:03
|  Below vertices are the blocks. Type blocks and  press  '''Enter'''. Insert a Open bracket and press '''Enter'''. 

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| 05:16
|Let me switch back to the slides.

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| 05:19
| Note that '''Lid driven cavity''' is taken as a single block.

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| 05:24
| Let me switch back to 'blockmeshdict'.

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| 05:27
|Enter the points for the blocks in the clockwise sense. 

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| 05:31
|We are using here '''hexa hedal blocks '''for '''meshing.'''

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| 05:34
|Now, type "hex". Leave some space. In brackets, enter ''' 0  space  1 2 3 4 5 6 7  ''', again leave some space.

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| 05:53
| Note that for multiple blocks, the points will be more. 

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|  05:58
|After this, enter the grid points in the x, y and z directions. 

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| 06:02
|In brackets, open close brackets, enter '''30 space 30 space 1'''. Leave some space, you can  modify the grid as and when needed. 

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|  06:16
|Grid point in z-axis can be taken as one. 

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|  06:22
|Now, leave some space and type "simple grading". Leave some space, open close bracket, enter '''1 space 1 space 1 '''.

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| 06:36
| This is the grid spacing in the x, y and z direction. Press  '''Enter'''.

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| 06:43
| Insert close bracket, insert a semicolon and press  '''Enter'''.

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| 06:48
| Again press '''Enter'''. Now type "edges" and press  '''Enter'''.
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| 06:55
|  As this is a simple geometry. edges can be kept empty. 

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| 07:00
|  Insert  open  bracket, press  '''Enter''',  close the  bracket, Insert  a semicolon and press  '''Enter'''.

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|  07:07
| Again press  '''Enter'''. Below '''edges''' are the '''boundary conditions'''. 

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|   07:11
| Here you need to enter the '''boundary name''' for the '''faces'''.

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|  07:15
|Type "boundary" and  press '''Enter''' . 

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| 07:19
|Insert an open bracket and press  '''Enter'''.

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| 07:23
|Now let me switch back to the slides. 

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|07:26	 
|In the geometry, the upper wall is moving and other three walls are fixed. 

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| 07:31
| The front and back faces are named as 'empty' as this is a 2D problem.

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| 07:39
| Open the new 'blockMeshDict' file again.

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|07:42
| In '''boundary''', put the name of the '''patch''' as 'moving wall' . Press  '''Enter'''.

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| 07:51
| Now, insert a open curly bracket and press  '''Enter'''.

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| 07:56
| Now enter the '''type''' for the '''moving wall''' , enter '''type''' space  '''wall'''.  

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| 08:06
| Insert a semicolon and press  '''Enter'''.
|-
| 08:09
|Now insert open bracket and press '''Enter'''. Press the tab key, open close bracket.
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|  08:20
|In this bracket, enter the point for faces.
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|  08:24
|Let me switch to the slide.

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| 08:27
| Note that order of the points  should be in such a way that the '''thumb''' should be '''normal''' to the '''face '''.

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|  08:34
| And fingers making a  curl  as shown in the figure.

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|  08:39
|The curl can be clockwise or anti-clockwise. 
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|  08:43
| Also, note that the points should match with the points inserted in vertices.

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|  08:48
|Now, let me switch back to the new 'blockmeshdict' file.

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|  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 points for the moving wall 3, 7, 6, 2.

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| 09:09
|Minimize this. Note that you can start from any point on that face. Now press  '''Enter'''.
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| 09:17
|Close the bracket again, press  '''Enter'''. Close the curly bracket.
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| 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'''.

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| 09:35	
|Now, similarly enter '''boundary condition''' and '''faces''' for the '''fixed wall '''.

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| 09:40
| Being a 2D problem the type of boundary for front and back faces can be kept as empty.
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| 09:46
|Refer to the figure in the slide. For entering the points, minimize this.

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| 09:52
| Insert the closed brackets,  put a semicolon and press  '''Enter''',  again press  '''Enter'''.

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| 09:59
|Now type "mergePatchPairs" and press  '''Enter'''.

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| 10:04
| Since there are no patches to merge, it can be kept empty.
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| 10:08
| Insert open close bracket. Insert a semicolon and press  '''Enter'''.
|-
| 10:14
| We are done with creating the  'blockmeshdict' file. '''Save''' this. 	   
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| 10:18
| The complete 'blockMeshDict' file is as shown here. 

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|10:26
| Close  both the 'blockMeshDict' files.

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| 10:29
| Note that the '''command terminal''' will not work until '''blockMeshDict''' file is closed. 

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|  10:35
|  Switch back to the terminal. Now, type '''cd (dot) (dot)''' twice to return back to the 'cavity' folder. Now '''Mesh the geometry'''. 

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|10:45
|To do this, on the '''terminal''', type: "blockMesh" and press  '''Enter'''.

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| 10:53
|Now, view the '''geometry''' by typing in the '''command terminal''' '''paraFoam''' and press  '''Enter'''.

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| 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.

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| 11:13
| Now let me switch back to  the slides.

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| 11:16
|  In this tutorial, we learnt: 

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| 11:18
|* Creating a simple geometry in '''OpenFOAM''' 

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| 11:22
|* Viewing the '''geometry''' in '''Paraview '''.

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| 11:25
| This brings us to the end of the tutorial. 

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| 11:29
| As an Assignment- 

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| 11:31
| Change the direction  of '''lid driven cavity''', change  the '''grid size''' to '''50 50 1'''and 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. 
|}