OpenFOAM/C3/Generating-Mesh-using-snappyHexMesh/English-timed
From Script | Spoken-Tutorial
| Time | Narration |
| 00:01 | Hello and welcome to the spoken tutorial on generating mesh using snappyHexMesh in OpenFOAM. |
| 00:08 | In this tutorial, we will learn to:
Generate mesh using snappyHexMesh utility Simulate temperature distribution of a flange. |
| 00:18 | As a pre-requisite, you should know parameters in snappyHexMeshDict to generate mesh.
For more details, refer the tutorial on introduction to snappyHexMesh in OpenFOAM. |
| 00:31 | To record this tutorial, I am using:
Ubuntu Linux Operating system version 12.04. OpenFOAM version 2.2.2 ParaView version 3.12.0 |
| 00:46 | We are solving an existing case of flange fromlaplacianFoam in basic directory.
'laplacianFoam' solver solves simple Laplace equations. |
| 00:58 | Now, let us go to home folder and click on OpenFoam-2.2.2 folder. |
| 01:05 | You will see tutorials. Click on it. |
| 01:09 | Then click on mesh folder. |
| 01:12 | You will see the snappyHexMesh folder. Click on it. |
| 01:17 | In this folder, create a new folder by name flange_1. |
| 01:24 | Now, let's go back two levels. |
| 01:27 | Open the basic folder. You will see laplacianFoam folder. Click on it. |
| 01:36 | You will see flange case. Click on it to open the folder. |
| 01:42 | Copy the three folders 0, constant and system. |
| 01:46 | Now, let us go three levels back. Paste the copied folders inside the flange_1 folder. |
| 01:56 | Now, let us go one level back. Click on flange folder. You will see constant and system folders. |
| 02:05 | Click on system folder. |
| 02:08 | Copy snappyHexMeshDict and surfaceFeatureExtractDict from this folder. Now, let us go two levels back. |
| 02:18 | Paste these two files inside the system directory of flange_1 folder. |
| 02:27 | Now, let us go one level back. Click on constant folder. In this, create a folder by name triSurface. |
| 02:40 | Now, let us go four levels back. |
| 02:44 | Open the resources folder. |
| 02:48 | You will see geometry folder. Now, open the geometry folder. |
| 02:53 | In this, you will see flange.stl.gz file. Extract this file. |
| 03:04 | Give the path of triSurface folder in constant directory of flange_1 folder. Now close this. |
| 03:16 | Open command terminal and enter the path for flange_1 as shown. Type: cd space OpenFOAM-2.2.2/tutorials/mesh/snappyHexMesh/flange_1 and press Enter. |
| 03:42 | Now type "ls" and press Enter. |
| 03:46 | There are three folders 0, constant and system. Type cd space constant and press Enter. |
| 03:55 | Now type "ls" and press Enter. You will see the polymesh and triSurface folders.Type: cd space polymesh and press Enter. |
| 04:09 | Now type: "ls" and press Enter. You can see the blockMeshDict file. |
| 04:16 | To view the contents of the file, type: gedit space blockMeshDict and press Enter. |
| 04:26 | This will open up the blockMeshDict file. This file contains co-ordinates for hex mesh and boundary patches. |
| 04:36 | Now close this and in the command terminal, type: cd (space) .. (dot) (dot) and press Enter. Again type: cd (space) .. (dot) (dot) and press Enter. |
| 04:48 | Now, type: cd space system and press Enter. |
| 04:53 | Now type: "ls" and press Enter. You can see the surfaceFeatureExtractDict file. |
| 05:01 | To view the contents of the file, type: gedit space surfaceFeatureExtractDict and press Enter(Note that F, E and D here are capital). |
| 05:15 | This will open up the surfaceFeatureExtractDict file. |
| 05:19 | This file contains the information about geometry’s feature edges. The included angle is taken as 150. |
| 05:29 | Now close this. In command terminal, type: gedit space snappyHexMeshDict and press Enter(Note that H, M and D here are capital). |
| 05:45 | This will open up the snappyHexMeshDict file. This file contains all the instructions about snappyHexMesh. |
| 05:53 | In snappyHexMeshDict, I have already made some changes. I have named flange.stl same as that of STL file which is in the constant/trisurface directory. |
| 06:11 | For Explicit feature edge refinement in castellatedMeshControls, I have given the file name flange.eMesh. This file is obtained by surfaceFeatureExtract utility. |
| 06:23 | The remaining details in the snappyHexMesh have changed as per requirements. |
| 06:30 | Now close this and in command terminal, type cd (space) .. (dot) (dot) and press Enter. |
| 06:38 | Type: cd space 0 (zero) and press Enter. |
| 06:44 | Type "ls" and press Enter. You can see the 'T' file. |
| 06:50 | Now type: gedit space T and press Enter. |
| 06:55 | This will open up the 'T' file. You will see the initial conditions for every patch. |
| 07:04 | Now, we have to give initial conditions for all patches of flange. |
| 07:11 | Copy the initial conditions for patch 1 and paste it after patch 4, in the same file 'T.' Now type "flange_" before this patch 1. |
| 07:28 | Similarly, we can do this for patch 2, 3 and 4. Save this 'T' file and close it. |
| 07:37 | And, in the command terminal type: cd (space) .. (dot) (dot)and press Enter. |
| 07:43 | Now, we need to mesh the geometry. For that, in command terminal, type: blockMesh and press Enter. Meshing is done. |
| 07:55 | Now type: surfaceFeatureExtract and press Enter (Note that F and E here are capital).Surface feature extraction is done. |
| 08:09 | Now, type: snappyHexMesh -(dash) overwrite and press Enter. - (dash) overwrite command will prevent copying the files from the last time folders. |
| 08:24 | If not, the resulting meshes will be inside the next time folders, possibly the folders 1, 2 and 3. |
| 08:31 | Meshing will take some time. Now meshing is completed. |
| 08:36 | For simulating temperature distribution, we are using 'laplacianFoam' solver. |
| 08:42 | In the command terminal, type: laplacianFoam and press Enter (Note that F here is capital). |
| 08:51 | Iterations running will be seen in the terminal window. |
| 08:55 | Once solving is completed, type: paraFoam and press Enter to view the geometry and the results. This will open up the Paraview window. |
| 09:07 | On the left hand side of Paraview window, click on Apply. The geometry can be seen here. |
| 09:15 | Scroll down the properties panel of the Object Inspector menu. Check the box for T in the Volume Fields and click on Apply. |
| 09:25 | Now go to the top of Active variable control drop-down menu. Change from solid color to capital 'T', which is the initial condition for the flange. |
| 09:37 | Now on the top of the Paraview window, you can see the VCR controls. Click on the Play button. Now, this is the final result for temperature distribution of a flange. |
| 09:58 | Toggle on the color legend by clicking on top left of the Active variable control menu.This is the colour legend for temperature T. |
| 10:09 | Now, let me get back to the slides. |
| 10:12 | This brings us to the end of the tutorial. As an assignment- |
| 10:16 | Change some parameters in the snappyHexMeshDict:
Refinement parameters locationInMesh co-ordinates snapControls etc. |
| 10:26 | You can also change the temperature in the '0' (zero) folder and view the results in the Paraview. |
| 10:33 | In this tutorial, we learnt :
To generate mesh by snappyHexMesh utility in OpenFoam. Simulate temperature distribution of a flange. |
| 10:44 | 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. |
| 10:57 | 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 |
| 11:14 | Spoken Tutorials are part of Talk to a Teacher project. It is supported by 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 |
| 11:29 | This is Chaitrali Ghodke from IIT Bombay, signing off. Thanks for joining. |
