Difference between revisions of "OpenFOAM/C2/Creating-simple-geometry-in-OpenFOAM/English-timed"

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Revision as of 17:40, 9 July 2014

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
12:19 This is Rahul Joshi from IIT BOMBAY signing off.

Thanks for joining.

Contributors and Content Editors

DeepaVedartham, Gaurav, PoojaMoolya, Pratik kamble, Sandhya.np14, Sneha