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 a simple geometry in OpenFOAM |
| 00:06 | In this tutorial I will show you |
| 00:08 | How to create a simple geometry |
| 00:11 | How to view the geometry in paraview |
| 00:15 | To record this tutorial |
| 00:16 | I am using Linux Operating system Ubuntu version10.04 OpenFOAM version 2.1.0 ParaView version 3.12.0 |
| 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 he earlier tutorial, |
| 00:41 | 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 constant and press enter |
| 01:03 | NowType ls and press enter |
| 01:06 | In this there is another folder called as polymesh |
| 01:10 | Now type cd 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 blockMeshDict( Note that M and D are capital) and press enter |
| 01:45 | Let me drag this to the capture area |
| 01:49 | Now Minimise this |
| 01:53 | Let me switch back to the slides |
| 01:55 | In openfoam the entire geometry is broken into blocks |
| 02:02 | The blocks are numbered starting from 0 as shown in the figure |
| 02:08 | Note that in OpenFOAM for creating a 2D geometry |
| 02:12 | you need to give a a unit cell thickness value in the z-axis. |
| 02:19 | lid driven cavity is of length 1 and height 1 minimise the slide |
| 02:29 | On your desktop create an empty file by |
| 02:33 | 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 |
| 02:55 | 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 |
| 03:31 | Again press Enter in 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 |
| 04:57 | close the bracket and insert a semicolon after it. Press enter,again press enter |
| 05:04 | Below vertices are the blocks. Type blocks and press enter. Insert a Open bracket and press enter |
| 05:17 | 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 theclockwise sense |
| 05:31 | We are using here hexa hedal blocks for meshing. |
| 05:34 | Now type hex leave some space |
| 05:39 | in brackets enter ( 0 space 1 2 3 4 5 6 7 ) again leave some space
|
| 05:54 | Note thatFor 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 enter (30 space 30 space 1) ,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 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 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 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 |
| 10:19 | The complete blockMeshDict file is as shown here. |
| 10:26 | Close the both the blockMeshDict files
|
| 10:29 | Note that the command terminal will not work until blockMeshDict file is closed |
| 10:35 | Come back to the termina.l now type cd (dot) (dot) twice to return back to the cavity folder. Now Mesh the geometry |
| 10:46 | 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 |
| 11:00 | This will open the ParaView window |
| 11:04 | Now On the left hand side click Apply on object inspector menuthus you can see the geometry. |
| 11:13 | now let me switch back to theslides |
| 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 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. |
| 11:47 | 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 |
| 12:09 | This is Rahul Joshi from IIT BOMBAY signing off.
Thanks for joining. |
Contributors and Content Editors
DeepaVedartham, Gaurav, PoojaMoolya, Pratik kamble, Sandhya.np14, Sneha
