Difference between revisions of "OpenFOAM/C3/Creating-and-Meshing-aerofoil-in-Gmsh/English-timed"

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| 06:04
 
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| Now, we will extrude the surface to make it 3D. Go to '''Translate''', '''Extrude Surface.'''  
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| Now, we will extrude the surface to make it 3D. Go to '''Translate >> Extrude Surface.'''  
  
 
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| A new window will appear asking for cordinates for translation.
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| A new '''window''' will appear asking for the coordinates for translation.
  
 
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| Since we want to extrude the surface in positive Z direction,  
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| Since we want to extrude the surface in Z direction, enter the coordinates for Z direction as 1.
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And, click on the boundary of the surface.  
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* enter the coordinates for Z direction as 1
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* and click on the boundary of the surface.  
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| Use the left click of the mouse to move the geometry.  
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| Use the left click of the '''mouse''' to move the '''geometry'''.  
  
 
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| Close this. Close the '''gmsh '''window
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| Close this. Close the '''gmsh '''window.
  
 
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| Inside '''Extrude '''add these lines :
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| Inside '''Extrude''', add these lines:
  
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'''Layers{1};''' Press Enter
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'''Layers{1};''' Press '''Enter'''.
  
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'''Recombine;'''Save this file.
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'''Recombine;''' '''Save''' this file.
  
 
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| Now in the '''terminal '''window, open the '''geo '''file.
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| Now, in the terminal window, open the '''geo '''file.
  
 
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| Now we have our geometry, we will do the meshing.
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| Now we have our geometry, we will do the '''meshing'''.
  
 
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| '''Gmsh''' automaticaly generates the mesh of the defined geometry.  
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| '''Gmsh''' automatically generates the mesh for the defined geometry.  
  
 
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| We can also refine the mesh by clicking on the '''Refine by Splitting '''parameter in the mesh menu.  
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| We can also refine the '''mesh''' by clicking on the '''Refine by Splitting '''parameter in the '''mesh''' menu.  
  
 
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| Now let us save our work.  
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| Now, let us '''save''' our work.  
  
 
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| Go to '''File''' menu and click on '''Save as. '''
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| Go to '''File''' menu and click on '''Save as.'''
  
 
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| And type the name the file as '''aerofoil.msh'''  
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| And type the name of the file as '''aerofoil.msh'''.
  
 
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| Click '''Ok ''' Again click '''Ok'''
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| Click '''OK '''. Again click '''OK'''.
  
 
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| As an '''assignment''' create another '''aerofoil''' by using different '''dat '''file for different '''aerofoil '''shapes.  
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| As an assignment, create another '''aerofoil''' by using different '''dat '''file for different '''aerofoil '''shapes.  
  
 
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|08:37
 
|08:37
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| In this tutorial we learnt:  
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| In this tutorial, we learnt:  
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* How To create an aerofoil in Gmsh.  
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* How to create an '''aerofoil''' in '''Gmsh'''.  
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* How to do meshing in Gmsh
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* How to do '''meshing''' in '''Gmsh'''.
  
 
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| 08:45
 
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| Watch the video available at this URL:
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| Watch the video available at this URL.
 
It summarizes the Spoken Tutorial project.  
 
It summarizes the Spoken Tutorial project.  
  
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| The Spoken Tutorial Project Team.Conducts workshops using spoken tutorials  
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| The Spoken Tutorial Project team: Conducts workshops using spoken tutorials.
  
 
|-
 
|-
 
| 09:00
 
| 09:00
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| Gives certificates to those who pass an online test  
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| Gives certificates to those who pass an online test.
  
 
|-
 
|-
 
| 09:03
 
| 09:03
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| For more details, please write to us contact@spoken-tutorial.org  
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| For more details, please write to us at:
 +
'''contact@spoken-tutorial.org'''
  
 
|-
 
|-
 
| 09:06
 
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| Spoken Tutorials are part of Talk to a Teacher project,
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| '''Spoken Tutorials''' are part of '''Talk to a Teacher''' project.
  
 
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| 09:15
 
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| More information on the same is available at the following URL link [http://spoken-tutorial.org/NMEICT-Intro http://spoken-tutorial.org/NMEICT-Intro]
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| More information on the same is available at the following URL:
 +
http://spoken-tutorial.org/NMEICT-Intro  
  
 
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| 09:19
 
| 09:19
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| The script was written by Gautam Sharma and this is Rahul Joshi from IIT Bombay signing off. Thanks for joining.
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| The script was written by Gautam Sharma and this is Rahul Joshi from '''IIT Bombay''', signing off. Thanks for joining.
  
 
|}
 
|}

Revision as of 18:25, 5 July 2016

Time Narration
00:01 Hello and welcome to the spoken tutorial on Creating and Meshing aerofoil in Gmsh.
00:08 In this tutorial, we will learn how to create an aerofoil using Gmsh
00:14 and mesh the created aerofoil.
00:17 As a prerequisite, the user should have knowledge of aerofoil and Gmsh.
00:23 If not, for Gmsh, please see the tutorial on Installing and running Gmsh on the spoken tutorial website.
00:31 To record this tutorial, I am using:
  • Ubuntu Linux Operating system version 14.04 and
  • Gmsh version 2.8.3
00:42 Let me introduce you to aerofoil.
00:45 Aerofoils are streamline shaped wings which are used in airplanes and turbo machinery.
00:53 These shapes are such that the drag force is a very small fraction of the lift.
00:59 This is a picture of an aerofoil.
01:03 The predefined coordinates for aerofoil are available in simple text file with ".dat" extension.
01:11 I will download the .dat file and Python script from this url:
01:19 Let me open the website.
01:22 Download the .dat file and the Python script and go to the Downloads folder.
01:31 Copy and paste both these files on the Desktop from the Downloads folder.
01:37 Open the .dat file.
01:40 This file contains the calculated X and Y coordinates for each point that defines the aerofoil.

Z coordinate is kept as zero.

01:51 We need the X, Y and Z co-ordintes in Gmsh acceptable format.
01:56 This can be done manually but this is time consuming.
02:01 Now open the Python script.
02:04 This Python script converts the data in the .dat file and gives the output in a separate file which is understood by Gmsh.
02:14 Now open the Terminal window. Type: cd space Desktop.
02:21 Now type: python space dat2gmsh.py space, the name of the dat file and press Enter.
02:31 Now type ls. We can see that a new file by the name naca5012xyz.dat .geo will be generated.
02:43 Open the geo file.
02:46 This contains the co-ordinates in Gmsh format.
02:50 Here, nac_lc is the characteristic length which is defined in the first line as is 0.005.
02:59 I will change this to 0.5.
03:03 This is because we require a coarser mesh.
03:07 You can change this value according to your mesh requirement. Now save this file.
03:15 In the terminal window, type: gmsh space, name of the geo file and press Enter.
03:25 This opens gmsh with the aerofoil.
03:29 Now, zoom in by scrolling at the tail end of the aerofoil.
03:35 You will note that the aerofoil has an open trailing edge.
03:40 Close gmsh. Now go back to the geo file. Scroll down.
03:48 We will add the last point and join it.
03:53 Now, above spline, enter Point open close bracket 1046 space = open close curly bracket space 1.005 comma space -0.0005 comma space 0.00000 comma space nac_lc close it with a semicolon.
04:26 Modify the spline as Spline(1000) = curly braces open 1000 colon 1046 comma 1000 close the curly bracket semicolon.
04:44 Save the geo file.
04:47 Now, open the modified file in Gmsh. We can see that the edge is joined.
04:56 Now we will make a boundary around the aerofoil using points.
05:02 Enter these coordinates 4, 3, 0 and change the prescribed mesh element size to 0.5 .

Press Enter.

05:17 Similarly, add the other points.

4 -3 0

-4 -3 0

-4 3 0

05:29 Now, join the points with a straight line.
05:44 Now click on Plane surface and select the surface boundary.
05:52 Zoom-in and select the aerofoil as the hole boundary.
05:58 Press e to end selection. You can see we have our surface.
06:04 Now, we will extrude the surface to make it 3D. Go to Translate >> Extrude Surface.
06:14 A new window will appear asking for the coordinates for translation.
06:19 Since we want to extrude the surface in Z direction, enter the coordinates for Z direction as 1.

And, click on the boundary of the surface.

06:30 Press e to end selection.
06:33 Use the left click of the mouse to move the geometry.
06:37 You can see that the geometry has been extruded.
06:42 Close this. Close the gmsh window.
06:45 Open the geo file.
06:48 Scroll down and go to Extrude.
06:52 Inside Extrude, add these lines:

Layers{1}; Press Enter.

Recombine; Save this file.

07:09 This will ensure that the mesh is one element thick.
07:14 Now, in the terminal window, open the geo file.
07:19 Now we have our geometry, we will do the meshing.
07:23 Gmsh automatically generates the mesh for the defined geometry.
07:28 Go to Mesh.
07:30 Click on 1D mesh, 2D mesh and 3D mesh.
07:36 The mesh has been generated.
07:39 You may notice that the mesh is finer near the aerofoil and gets coarser as we move towards the boundary.
07:48 We can also refine the mesh by clicking on the Refine by Splitting parameter in the mesh menu.
07:56 Now, let us save our work.
07:59 Go to File menu and click on Save as.
08:05 A new window will appear. In the drop down, change to the mesh format.
08:11 And type the name of the file as aerofoil.msh.
08:17 Note that here msh stands for the file type mesh.
08:22 Click OK . Again click OK.
08:26 This brings us to the end of the tutorial.
08:29 As an assignment, create another aerofoil by using different dat file for different aerofoil shapes.
08:37 In this tutorial, we learnt:
  • How to create an aerofoil in Gmsh.
  • How to do meshing in Gmsh.
08:45 Watch the video available at this URL.

It summarizes the Spoken Tutorial project.

08:52 If you do not have good bandwidth, you can download and watch it.
08:56 The Spoken Tutorial Project team: Conducts workshops using spoken tutorials.
09:00 Gives certificates to those who pass an online test.
09:03 For more details, please write to us at:

contact@spoken-tutorial.org

09:06 Spoken Tutorials are part of Talk to a Teacher project.
09:09 It is supported by the National Mission on Education through ICT, MHRD, Government of India.
09:15 More information on the same is available at the following URL:

http://spoken-tutorial.org/NMEICT-Intro

09:19 The script was written by Gautam Sharma and this is Rahul Joshi from IIT Bombay, signing off. Thanks for joining.

Contributors and Content Editors

PoojaMoolya, Pratik kamble, Sandhya.np14

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