OpenFOAM/C3/Creating-a-sphere-in-GMSH/English
Tutorial: Creating a sphere in GMSH
Script and Narration: Pavan Mehta
Keywords: Video tutorial, CFD, GMSH, unstructured mesh, curved lines, circular arc, ruled surface
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Slide 1 | Hello and welcome to the spoken tutorial on Creating a sphere in GMSH. |
Slide 2: Learning Objective | In this tutorial, we will learn to
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Slide 3: System requirement | To record this tutorial I am using
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Slide 4: Pre-requisite | As a pre-requisite, user should have basic knowledge of creating points.
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Slide 5: Points for sphere | Let us begin.
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Switch to terminal
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Let us now open GMSH from the terminal.
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Switch to GMSH's interface | I have already created 7 points for the sphere, as shown here.
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In GMSH's interface, selecting circle arc option | I'll now demonstrate how to make a circular arc.
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Select circle arc in LHS menu | To create an arc, select circle arc option in the left-hand-side menu. |
Creating curved lines by selecting 1st , 2nd and then 3rd point | Now, I will select the right-most point as the starting point of the arc.
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Pause recording and create all the arcs and complete the sphere. | Repeat the process till all arcs are created.
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Selecting the option ruled surface
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Now select ruled surface option from the left-hand side menu, to create the curved surface.
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Press E
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Press E on the keyboard to execute this selection.
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Pause recording and create all the surfaces
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Repeat the process and create all 8 surfaces of the sphere. |
Show the completed sphere | On completion, your sphere should look like this. |
Going to home folder and opening sphere1.geo text file, by double clicking | Now, go to the Home folder.
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Narration | Information related to the geometrical entities that we just created, are stored here. |
Explaining general syntax of GMSH | In GMSH, the general syntax is
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Explaining syntax of point
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Here, for point, the expression is
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Explaining further on syntax of point | This value is the desired mesh element size.
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Replacing the numerical value to a variable, s | Let us now replace the numerical value of the points of the sphere, to a variable, s. |
Type s=0.1; at the beginning of the document | At the beginning, type s = 0.1;
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Explaining the necessity of refinement
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To capture the boundary layer, we will refine the mesh near the sphere.
Mesh.CharacteristicLengthFromCurvature = 0.05; |
Explaining the syntax Mesh.CharacteristicLenghtFromCurvature | The syntax Mesh.CharacteristicLengthFromCurvature
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Type Surface Loop | For volume creation, we require all the bounding surfaces.
Surface Loop followed by its identity
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Saving and Closing the text file | Now save and close the sphere1.geo file. |
Switch to GMSH's interface
Select Physical Groups >> Add >> Surface option --> select all the surfaces --> Press E |
Let's switch to the GMSH interface.
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Double-click to open sphere1.geo file >> go to the last line of the file. | Now, again open sphere1.geo file in the Text Editor.
Right at the bottom, notice that a new line of code has been added. |
Replace this number with sphere in double inverted commas and explaining it's importance | Replace this number with sphere within quotes.
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Save and close the file. | Now save and close the file. |
Narration | This completes this tutorial. Let us summarize. |
Slide 6: Summary | In this tutorial we learnt to
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Slide 7: Assignment | As an assignment,
Create a sphere with a larger radius. |
Slide 8: About FOSSEE | OpenFOAM series is created by the FOSSEE Project, IIT Bombay.
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Slide 9: About the Spoken tutorial project
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The video at this link summarises the Spoken Tutorial project.
Please download and watch it. |
Slide 10:
Spoken tutorials Workshops
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The Spoken Tutorial Project Team conducts workshops and gives certificates on passing online tests.
For more details, please write to us. |
Slide 11: Acknowledgement | Spoken Tutorial Project is funded by NMEICT, MHRD, Government of India.
More information on this Mission is available at this link.
Thanks for joining. |