OpenFOAM/C3/Installing-and-running-Gmsh/English

Tutorial: Installing and runing Gmsh

Script : Gautam Sharma

Narration: Rahul Joshi

Keywords: Gmsh, OpenFOAM, Geometry, Finite Element Mesh..

Visual Cue	Narration
Slide 1	Hello and welcome to the spoken tutorial on Installing and running Gmsh.
Slide 2 : Learning Objectives	In this tutorial we will learn how to Install and run Gmsh and create a basic geometry in Gmsh
Slide 2: Pre-requisite	As a pre-requisite, the user should have basic knowledge about mesh.
Slide 3: System Requirement	To record this tutorial, I am using Ubuntu Linux Operating system version 12.04 and Gmsh version 2.8.5
Slide 4: About Gmsh	Let me introduce you to Gmsh. Gmsh is an automatic 3-D finite element mesh generator, with built-in pre and post-processing facilities. It's an Open-source software.
Slide 5 : Advantageous in creating complex geometry using blockMesh	It is advantageous in creating complex geometries in gmsh than blockmesh utility of OpenFOAM. like blades, aerofoil. OpenFOAM supports importing mesh from third party meshing software like Gmsh.
Installing Gmsh	Let me show you how to install Gmsh. Gmsh can be installed using Synaptic Package Manager.
Synaptic Package Manager Gmsh installed	Let me open Synaptic Package Manager for you. It will ask for your password. Type in your password. In search box type gmsh. Click on the checkbox in front of gmsh. And click on Mark for installation. Click on Apply. Again click on Apply. This might take some time. Your Gmsh is now installed.
Open browser	Alternately, you can also download Gmsh from the Gmsh website. Let me open the browser for you.
Type: http://geuz.org/gmsh/	In the address bar, type: http://geuz.org/gmsh/ Press Enter.
Scroll down to stable Linux release Linux 64-bit	Scroll down to Downloads and select the current stable release according to your operating system. I will select Linux 64-bit. Click on Save file and press Ok.
Go to Home>> Downloads Locate the file gmsh-2.8.4-Linux64.tgz	After finishing your download, go to the Downloads folder.
Extract the files	Here you can see the tar file. Extract the file. A new folder will be created.
Open Gmsh folder	Open the folder. Go to bin and click on gmsh icon.
Gmsh start screen	You can see the Gmsh start screen.
Cube	Now we will create a cube using Gmsh.
Diagram	Here you can see the cube with side equal to one unit.
Gmsh window	Let me switch back to Gmsh. On the left hand side, you can see the module tree with Geometry, Mesh and Solver.
Click Add	Go to Geometry - Elementary entitites - Add.
Enter the coordinates of the cube	Click on Point. A new window will appear.
Enter the coordinates	Enter the X,Y and Z coordinates starting with (0 0 0) and press Enter.
(1 0 0) (1 1 0) (0 1 0) z-direction coordinates	Enter the second coordinate as (1 0 0) and press Enter. The third coordinate as (1 1 0) and press Enter. The fourth coordinate as (0 1 0) and press Enter. Similarly, enter the coordinates for the positive z-direction starting with point (0 0 1) and press Enter. Enter the remaining three coordinates and close the window.
Coordinates	I have entered all the eight coordinates.
Move the points	Use the left mouse click to move the points.
8 points visible	You can see all the 8 coordinates as points.
Join the points by Straight lines	Now, click on Straight line.
Select start point	It wiil ask for start point . Select the first point.
Select end point	It will ask for end point . Select the second point.
Straight line	A line will be drawn between the two points. Similarly, join all the points.
Press q to abort	Press q to abort.
Define the faces	Now we will define the faces of the cube.
Click on Plane Surface	Click on Plane surface. It will ask for the surface boundary.
Select the edges Selected boundary appear in red Press e to end selection	Select the edges of the bottom face first. You will notice that the edge we select, turns in red color. It will ask for hole boundaries, if any. Since we don't have any hole in the boundary, press e to end the selection.
Face appears with centre lines	You will notice that the the face will appear with dashed centre lines.
Define the top face	Now define the top face.
Select the remaining faces	Similarly, define the remaining faces. I have defined all the faces. Press q to abort.
Define the Volume	Now, we will define the volume of the cube. It will ask for the volume boundary.
Select the volume boundary	Select any of the surface boundary and press e to end selection.
Green dot appears at centre	A yellow dot appears at the centre of the cube, which represents the volume. Press q to abort.
Define physical groups	Now, we will define the physical groups, which will be used in exporting the geometry to OpenFOAM.
Define surface first	Go to Physical Group - Add and click on Surface.
Select the surface boundary	Select the front surface first and press e to end the selection. Select the back surface and press e to end the selection.
Select the remaining face	Similarly, select the remaining surfaces. I have selected all the surfaces. Press q to abort.
Define the physical volume. Click on volume. Click on the yellow dot Dot appears in red	Now, we'll define the physical volume. Click on Volume. It will ask for volume. Click on the yellow dot at the centre of the cube. The yellow dot will turn red in color. Press e to end selection. Press q to abort.
Save you work	Our cube is complete. Let us save our work.
Click on save as Cube.geo	Go to File - Save as. We will name our file as cube.geo Note that here geo stands for geometry. Click Ok. Again click Ok.
Slide : Assignment	This brings us to the end of this tutorial. As an assignment, create other simple geometry in Gmsh like cylinder and sphere.
Slide : Summary	In this tutorial we learnt : 2 ways to install and run Gmsh using Synaptic Package Manager and website. Created a cube using Gmsh.
Slide : About Spoken tutorials	This video summarizes the Spoken Tutorial project. If you do not have good bandwidth, you can download and watch it.
Slide: About Spoken tutorials	We conduct workshops using spoken tutorials and give certificates Please contact us at this URL contact@spoken-tutorial.org
Slide: Acknowledgement	Spoken Tutorial is funded by NMEICT, MHRD, Government of India.
About the contributor	The script was created by Gautam Sharma and this is Rahul Joshi from IIT BOMBAY signing off. Thanks for joining.

Contributors and Content Editors

Gautam, Nancyvarkey, Rahuljoshi