Difference between revisions of "OpenFOAM/C3/Introduction-to-SnappyHexMesh/English-timed"

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(Created page with "{| border=1 | '''Time''' | '''Narration''' |- | 00:00 | Hello and welcome to the spoken tutorial on Introduction to '''snappyHexMesh''' in '''OpenFOAM'''. |- | 00:07 | In th...")
 
 
(4 intermediate revisions by 2 users not shown)
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|-
 
|-
 
| 00:00
 
| 00:00
−
| Hello and welcome to the spoken tutorial on Introduction to '''snappyHexMesh''' in '''OpenFOAM'''.
+
| Hello and welcome to the '''spoken tutorial''' on '''Introduction to snappyHexMesh''' in '''OpenFOAM'''.
  
 
|-
 
|-
 
| 00:07
 
| 00:07
 
| In this tutorial, we will learn about  
 
| In this tutorial, we will learn about  
−
The parameters in '''snappyHexMesh'''  
+
the parameters in '''snappyHexMesh'''  
−
To generate '''Mesh''' in '''OpenFOAM'''.
+
to generate '''Mesh''' in '''OpenFOAM'''.
  
 
|-
 
|-
 
|00:14
 
|00:14
−
| As a pre-requisite, the user requires
+
| As a pre-requisite, the user requires:
−
* Surface data files in '''STL''' format, located in '''constant/trisurface''' sub-directory of the '''case''' directory
+
Surface data files in '''STL''' format, located in '''constant/trisurface''' sub-directory of the '''case''' directory
−
* A domain with '''hex mesh'''
+
A domain with '''hex mesh'''
−
* '''snappyHexMeshDict''' dictionary located in the '''system''' sub-directory of''' case'''
+
'''snappyHexMeshDict''' dictionary located in the '''system''' sub-directory of''' case'''.
  
 
|-
 
|-
 
| 00:35
 
| 00:35
−
| To record this tutorial, I am using  
+
| To record this tutorial, I am using:
−
* '''Ubuntu Linux''' operating system 12.04
+
'''Ubuntu Linux operating system''' 12.04
−
* '''OpenFOAM''' version 2.2.2
+
'''OpenFOAM''' version 2.2.2
−
* '''ParaView''' version 3.12.0
+
'''ParaView''' version 3.12.0
  
 
|-
 
|-
 
| 00:50
 
| 00:50
−
| Let us learn to create a Mesh with the '''snappyHexMesh''' utility.
+
| Let us learn to create a '''Mesh''' with the '''snappyHexMesh''' utility.
  
 
|-
 
|-
Line 38: Line 38:
 
Step 3 : Remove unused '''cells'''
 
Step 3 : Remove unused '''cells'''
 
Step 4 : '''Snap mesh''' to surface
 
Step 4 : '''Snap mesh''' to surface
−
Step 5 : Add layers
+
Step 5 : Add '''layers'''.
  
 
|-
 
|-
 
| 01:18
 
| 01:18
−
| We will open the '''terminal '''and enter the path for '''flange '''as shown.
+
| We will open the '''terminal '''and enter the '''path''' for '''flange '''as shown. Type: '''cd space OpenFOAM-2.2.2/tutorials/mesh/snappyHexMesh/flange''' and press '''Enter'''.
−
Type '''cd OpenFOAM-2.2.2/tutorials/mesh/snappyHexMesh/flange''' and press '''Enter'''.
+
  
 
|-
 
|-
 
| 01:40
 
| 01:40
−
| Now type '''ls''' and press '''Enter.'''There are two folders '''constant '''and '''system'''.
+
| Now type "ls" and press '''Enter.''' There are two folders '''constant '''and '''system'''.
  
 
|-
 
|-
Line 55: Line 54:
 
|-
 
|-
 
| 01:55
 
| 01:55
−
| Now type '''ls''' and press '''Enter.'''You can see '''snappyHexMeshDict '''file.
+
| Now type '''ls''' and press '''Enter.''' You can see '''snappyHexMeshDict '''file.
  
 
|-
 
|-
 
| 02:04
 
| 02:04
−
| To view the contents of the file type -'''gedit snappyHexMeshDict '''and press '''Enter.'''
+
| To view the contents of the file, type: -'''gedit space snappyHexMeshDict '''and press '''Enter.'''(Note that H, M and D here are in capital letters.)
−
(Note that H, M and D here are in capital letters.)
+
  
 
|-
 
|-
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|-
 
|-
 
|02:50
 
|02:50
−
| The parameters that govern the process of cell splitting are described in '''castellatedMeshControls''' section.
+
| The '''parameter'''s that govern the process of cell splitting are described in '''castellatedMeshControls''' section.
  
 
|-
 
|-
 
| 02:58
 
| 02:58
−
| The parameters that are listed below are well explained in '''snappyHexMeshDict''' file.'''nCellsBetweenLevels''' defines number of cells for each refinement level.  
+
| The parameters that are listed below are well explained in '''snappyHexMeshDict''' file. '''nCellsBetweenLevels''' defines the number of cells for each refinement level.  
  
 
|-
 
|-
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|-
 
|-
 
|03:17
 
|03:17
−
| In the '''Explicit feature edge refinement''' section, you can set specific refinement level for geometry’s feature edges.The''' .eMesh''' file can be obtained with the '''surfaceFeatureExtract '''utility.
+
| In the '''Explicit feature edge refinement''' section, you can set specific refinement level for geometry’s feature edges. The ".eMesh" file can be obtained with the '''surfaceFeatureExtract '''utility.
  
 
|-
 
|-
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|-
 
|-
 
| 03:45
 
| 03:45
−
| Mesh selection is a very important parameter.If the chosen point is inside the surface described in '''geometry''' file, then '''snappyHexMesh''' will create the internal mesh.
+
| '''Mesh selection''' is a very important parameter. If the chosen point is inside the surface described in '''geometry''' file, then '''snappyHexMesh''' will create the internal mesh.
  
 
|-
 
|-
 
| 03:59
 
| 03:59
−
|Otherwise the external part (inside the blockMesh) is meshed.
+
|Otherwise, the external part (i.e. inside the blockMesh) is meshed.
  
 
|-
 
|-
 
| 04:04
 
| 04:04
−
| The next step involves moving cell vertex points onto the surface geometry.
+
| The next step involves moving '''cell''' vertex points onto the surface geometry.
  
 
|-
 
|-
 
| 04:12
 
| 04:12
 
| The '''snapping''' process is carried out by four parameters:
 
| The '''snapping''' process is carried out by four parameters:
−
* '''nSmoothPatch'''
+
'''nSmoothPatch'''
−
* '''tolerance'''
+
'''tolerance'''
−
* '''nSolveIter'''
+
'''nSolveIter'''
−
* '''nRelaxIter'''
+
'''nRelaxIter'''.
  
 
|-
 
|-
 
|04:23
 
|04:23
−
|These parameters control the number of iterations and tolerance between '''mesh''' and '''STL''' surface.
+
|These parameters control the number of '''iterations''' and '''tolerance''' between '''mesh''' and '''STL''' surface.
  
 
|-
 
|-
 
| 04:32
 
| 04:32
−
|'''nSmoothPatch '''option specifies the number of times the exterior ( that is the boundary wall) should be iterated.The '''mesh''' will become smoother if the number of iterations are more.
+
|'''nSmoothPatch '''option specifies the number of times the exterior (that is the boundary wall) should be iterated. The '''mesh''' will become smoother if the number of iterations are more.
  
 
|-
 
|-
 
| 04:46
 
| 04:46
−
|'''Tolerance''' option specifies the distance the program should look, for a point to '''snap'''.The distance will be the number that is in '''tolerance.'''
+
|'''Tolerance''' option specifies the distance the program should look for a point to '''snap'''. The distance will be the number that is in '''tolerance.'''
  
 
|-
 
|-
 
| 04:58
 
| 04:58
−
| '''nSolveIter '''option specifies the number of times the '''snapping''' part of '''snappyHexMesh '''should be run.
+
| '''nSolveIter '''option specifies the number of times the '''snapping''' part of '''snappyHexMesh '''should be '''run'''.
  
 
|-
 
|-
 
| 05:07
 
| 05:07
−
| '''nRelaxIter''' option specifies the number of times the mesh should run a relaxing script, that removes bad '''mesh''' points.
+
| '''nRelaxIter''' option specifies the number of times the mesh should '''run''' a relaxing script, that removes bad '''mesh''' points.
  
 
|-
 
|-
 
| 05:19
 
| 05:19
−
| The process of '''mesh''' layer addition involves shrinking the existing '''mesh''' from the boundary and inserting layers of cells.
+
| The process of '''mesh layer''' addition involves shrinking the existing '''mesh''' from the boundary and inserting layers of '''cell'''s.
  
 
|-
 
|-
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|-
 
|-
 
| 05:36
 
| 05:36
−
| '''RelativeSizes '''option ( that is true or false) changes the way to read the parameters given next.
+
| '''RelativeSizes '''option (that is '''true''' or '''false''') changes the way to read the parameters given next.
 
'''true''': next parameters define the layers' dimensions as parameters.
 
'''true''': next parameters define the layers' dimensions as parameters.
 
'''false''': next parameters define directly the layers' dimensions.
 
'''false''': next parameters define directly the layers' dimensions.
Line 154: Line 152:
 
|-
 
|-
 
| 05:55
 
| 05:55
−
| In '''layers''' option, you can define the number of '''layers''' and the patch on which to attach the '''layers'''.It must be an'''Bold text''' STL patch in '''geomery''' sub-menu, and not a user defined region.
+
| In '''layers''' option, you can define the number of '''layers''' and the '''patch''' on which to attach the '''layers'''. It must be an '''STL''' (Bold text)  patch in '''geomery''' sub-menu, and not a user defined region.
  
 
|-
 
|-
 
| 06:10
 
| 06:10
−
| '''ExpansionRatio''' parameters sets the growth factor of the '''layers''' (that is ratio between two subsequent layers).
+
| '''ExpansionRatio''' parameters set the growth factor of the '''layers''' (that is ratio between two subsequent layers).
  
 
|-
 
|-
 
| 06:19
 
| 06:19
−
| '''finalLayerThickness''' parameter sets the thickness of the last layer.'''minThickness''' parameter sets the minimum allowable thickness of layer.
+
| '''finalLayerThickness''' parameter sets the thickness of the last layer. '''minThickness''' parameter sets the minimum allowable thickness of layer.
  
 
|-
 
|-
 
| 06:34
 
| 06:34
−
|"'''Advanced settings''' is the second group of parameters.It contains more specific controls that can help in layer creation.
+
|'''Advanced settings''' is the second group of parameters. It contains more specific controls that can help in layer creation.
  
 
|-
 
|-
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|-
 
|-
 
| 06:52
 
| 06:52
−
| '''nRelaxIter''' option specifies the number of times the mesh will run a relaxing script.
+
| '''nRelaxIter''' option specifies the number of times the '''mesh''' will '''run''' a relaxing script.
  
 
|-
 
|-
 
| 07:00
 
| 07:00
−
| '''maxFaceThicknessRatio''' option specifiess the maximum allowable value of aspect ratio.
+
| '''maxFaceThicknessRatio''' option specifies the maximum allowable value of '''aspect ratio'''.
  
 
|-
 
|-
 
| 07:10
 
| 07:10
−
| meshQualityControls parameter sets the minimum thresholds to generate '''mesh''' in '''snap''' and add-layers parts.
+
| '''meshQualityControls''' parameter sets the minimum thresholds to generate '''mesh''' in '''snap''' and '''add-layers''' parts.
  
 
|-
 
|-
 
| 07:18
 
| 07:18
−
|In 99% of the cases, it is better to leave the default values.But sometimes, you can deactivate one or more controls to force mesh generation.
+
|In 99% of the cases, it is better to leave the '''default''' values. But sometimes, you can '''deactivate''' one or more controls to force mesh generation.
  
 
|-
 
|-
 
| 07:30
 
| 07:30
−
| These are the different parameters in '''snappyHexMeshDict'''.These parameters are important to generate '''mesh''' using '''snappyHexMesh''' utility.
+
| These are the different parameters in '''snappyHexMeshDict'''. These parameters are important to generate '''mesh''' using '''snappyHexMesh''' utility.
  
 
|-
 
|-
Line 198: Line 196:
 
|-
 
|-
 
| 07:42
 
| 07:42
−
| In this tutorial we learnt Different parameteres in '''snappyHexMesh '''to generate mesh in '''OpenFoam'''.
+
| In this tutorial, we learnt different parameters in '''snappyHexMesh '''to generate mesh in '''OpenFoam'''.
  
 
|-
 
|-
 
| 07:50
 
| 07:50
−
| Watch the video available at this URLhttp://spoken-tutorial.org/What_is_a_Spoken_Tutorial  
+
| Watch the video available at this URL:
−
It summarizes the Spoken Tutorial project. If you do not have good bandwidth, you can download and watch it.
+
http://spoken-tutorial.org/What_is_a_Spoken_Tutorial  
 +
It summarizes the Spoken Tutorial project.
 +
If you do not have good bandwidth, you can download and watch it.
  
 
|-
 
|-
 
| 08:03
 
| 08:03
−
| The Spoken Tutorial Project TeamConducts workshops using spoken tutorials
+
| The Spoken Tutorial Project team:
−
Gives certificates to those who pass an online test For more details, please write to  
+
Conducts workshops using spoken tutorials.
−
contact@spoken-tutorial.org
+
Gives certificates to those who pass an online test.
 +
For more details, please write to:'''contact@spoken-tutorial.org'''
  
 
|-
 
|-
 
| 08:21
 
| 08:21
−
| Spoken Tutorials are part of Talk to a Teacher project, It is supported by the National Mission on Education through ICT, MHRD, Government of India. More information on the same is available at following URL link http://spoken-tutorial.org/NMEICT-Intro
+
| '''Spoken Tutorial'''s are part of '''Talk to a Teacher''' project. It is supported by the National Mission on Education through ICT, MHRD, Government of India.  
 +
More information on the same is available at following URL:
 +
http://spoken-tutorial.org/NMEICT-Intro
  
 
|-
 
|-
 
| 08:37
 
| 08:37
−
| This is Chaitrali Ghodke from IIT BOMBAY signing off.Thanks for joining.
+
| This is Chaitrali Ghodke from '''IIT Bombay''', signing off. Thanks for joining.
  
 
|}
 
|}

Latest revision as of 15:47, 10 March 2017

Time Narration
00:00 Hello and welcome to the spoken tutorial on Introduction to snappyHexMesh in OpenFOAM.
00:07 In this tutorial, we will learn about

the parameters in snappyHexMesh to generate Mesh in OpenFOAM.

00:14 As a pre-requisite, the user requires:

Surface data files in STL format, located in constant/trisurface sub-directory of the case directory A domain with hex mesh snappyHexMeshDict dictionary located in the system sub-directory of case.

00:35 To record this tutorial, I am using:

Ubuntu Linux operating system 12.04 OpenFOAM version 2.2.2 ParaView version 3.12.0

00:50 Let us learn to create a Mesh with the snappyHexMesh utility.
00:55 The steps are as follows-

Step 1 : Create a base mesh by using blockMesh utility Step 2 : Refine base mesh Step 3 : Remove unused cells Step 4 : Snap mesh to surface Step 5 : Add layers.

01:18 We will open the terminal and enter the path for flange as shown. Type: cd space OpenFOAM-2.2.2/tutorials/mesh/snappyHexMesh/flange and press Enter.
01:40 Now type "ls" and press Enter. There are two folders constant and system.
01:50 Type cd space system and press Enter.
01:55 Now type ls and press Enter. You can see snappyHexMeshDict file.
02:04 To view the contents of the file, type: -gedit space snappyHexMeshDict and press Enter.(Note that H, M and D here are in capital letters.)
02:19 This will open up the snappyHexMeshDict file.
02:23 snappyHexMeshDict file contains all the instructions and the entire process revolves around this file.
02:32 With the first rows of snappyHexMeshDict, you can activate or skip sections of the process.
02:40 In the geometry section, all active regions that take part in snappy process can be defined.
02:50 The parameters that govern the process of cell splitting are described in castellatedMeshControls section.
02:58 The parameters that are listed below are well explained in snappyHexMeshDict file. nCellsBetweenLevels defines the number of cells for each refinement level.
03:12 The higher it is, the more gradual the mesh will be.
03:17 In the Explicit feature edge refinement section, you can set specific refinement level for geometry’s feature edges. The ".eMesh" file can be obtained with the surfaceFeatureExtract utility.
03:34 In the surface-based refinement section, you can set the refinement levels of all surfaces defined in geometry file.
03:45 Mesh selection is a very important parameter. If the chosen point is inside the surface described in geometry file, then snappyHexMesh will create the internal mesh.
03:59 Otherwise, the external part (i.e. inside the blockMesh) is meshed.
04:04 The next step involves moving cell vertex points onto the surface geometry.
04:12 The snapping process is carried out by four parameters:

nSmoothPatch tolerance nSolveIter nRelaxIter.

04:23 These parameters control the number of iterations and tolerance between mesh and STL surface.
04:32 nSmoothPatch option specifies the number of times the exterior (that is the boundary wall) should be iterated. The mesh will become smoother if the number of iterations are more.
04:46 Tolerance option specifies the distance the program should look for a point to snap. The distance will be the number that is in tolerance.
04:58 nSolveIter option specifies the number of times the snapping part of snappyHexMesh should be run.
05:07 nRelaxIter option specifies the number of times the mesh should run a relaxing script, that removes bad mesh points.
05:19 The process of mesh layer addition involves shrinking the existing mesh from the boundary and inserting layers of cells.
05:27 The first group of parameters define the dimensions for layers and surface, on which they will be attached.
05:36 RelativeSizes option (that is true or false) changes the way to read the parameters given next.

true: next parameters define the layers' dimensions as parameters. false: next parameters define directly the layers' dimensions.

05:55 In layers option, you can define the number of layers and the patch on which to attach the layers. It must be an STL (Bold text) patch in geomery sub-menu, and not a user defined region.
06:10 ExpansionRatio parameters set the growth factor of the layers (that is ratio between two subsequent layers).
06:19 finalLayerThickness parameter sets the thickness of the last layer. minThickness parameter sets the minimum allowable thickness of layer.
06:34 Advanced settings is the second group of parameters. It contains more specific controls that can help in layer creation.
06:45 FeatureAngle is the angle above which the surface will not be extruded.
06:52 nRelaxIter option specifies the number of times the mesh will run a relaxing script.
07:00 maxFaceThicknessRatio option specifies the maximum allowable value of aspect ratio.
07:10 meshQualityControls parameter sets the minimum thresholds to generate mesh in snap and add-layers parts.
07:18 In 99% of the cases, it is better to leave the default values. But sometimes, you can deactivate one or more controls to force mesh generation.
07:30 These are the different parameters in snappyHexMeshDict. These parameters are important to generate mesh using snappyHexMesh utility.
07:40 Let us summarize.
07:42 In this tutorial, we learnt different parameters in snappyHexMesh to generate mesh in OpenFoam.
07:50 Watch the video available at this URL:

http://spoken-tutorial.org/What_is_a_Spoken_Tutorial It summarizes the Spoken Tutorial project. If you do not have good bandwidth, you can download and watch it.

08:03 The Spoken Tutorial Project team:

Conducts workshops using spoken tutorials. Gives certificates to those who pass an online test. For more details, please write to:contact@spoken-tutorial.org

08:21 Spoken Tutorials are part of Talk to a Teacher project. It is supported by the National Mission on Education through ICT, MHRD, Government of India.

More information on the same is available at following URL: http://spoken-tutorial.org/NMEICT-Intro

08:37 This is Chaitrali Ghodke from IIT Bombay, signing off. Thanks for joining.

Contributors and Content Editors

PoojaMoolya, Pratik kamble, Sandhya.np14

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