OpenFOAM/C2/Simulating-flow-in-a-Lid-Driven-Cavity/English-timed
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| Time | Narration |
| 00:01 | Hello and welcome to the spoken tutorial on Simulating Flow in a Lid Driven Cavity using openFoam. |
| 00:07 | In this tutorial, I will show you: |
| 00:09 | * The Lid Driven Cavity file structure |
| 00:12 | * Meshing the Geometry |
| 00:14 | * Solving and post-processing results in Paraview |
| 00:17 | * Plotting & validating results on a spreadsheet. |
| 00:21 | To record this tutorial, |
| 00:22 | I am using: Linux Operating system Ubuntu version 10.04 |
| 00:27 | OpenFOAM version 2.1.0 and ParaView version 3.12.0. |
| 00:32 | Lid driven cavity is the most widely used 2D test |
| 00:36 | case for validation of a CFD code. |
| 00:39 | This is the diagram of Lid Driven Cavity, |
| 00:41 | the boundary conditions remain the same. |
| 00:44 | A moving wall and three fixedwalls. |
| 00:46 | We are solving this for Reynolds no (Re) = 100. |
| 00:50 | The moving wall has a velocity of 1 meter per second. |
| 00:54 | The path for the Lid Driven Cavity is the same as discussed in the installation tutorial. |
| 01:00 | Now, open a command terminal. |
| 01:02 | To do this, press Ctrl+Alt+t keys simultaneously on your keyboard. |
| 01:08 | In the command terminal, type the path for the lid driven cavity |
| 01:12 | and type "run" and press Enter. |
| 01:15 | cd (space) tutorials and press Enter. |
| 01:20 | cd (space) incompressible and press Enter. |
| 01:26 | cd (space) icoFoam (Note that F here is capital) and press Enter. |
| 01:33 | cd (space) cavity and press Enter. |
| 01:38 | Now, type "ls" and press Enter. |
| 01:41 | In the file structure of cavity, you will see 3 folders : 0 , constant , and system. |
| 01:46 | Now, type cd (space) constant and press Enter. |
| 01:52 | Now type "ls" and press Enter. |
| 01:55 | The constant folder contains another folder named polyMesh and a file describing the physical properties of fluid. |
| 02:01 | Now, type cd (space) polymesh and Press Enter. |
| 02:08 | PolyMesh contains a file named 'blockMeshDict'. |
| 02:12 | Now type "ls" and press Enter. |
| 02:15 | You can see the blockMeshDict |
| 02:17 | To open up the blockMeshDict file, type gedit space blockMeshDict.
(Note that M and D here are capital) Now press Enter. |
| 02:30 | This will Open up the blockMeshDict file. |
| 02:32 | Let me drag this to the capture area. |
| 02:36 | This contains: coordinates for the lid driven cavity, |
| 02:41 | blocking and meshing parameters |
| 02:44 | and boundary patches. |
| 02:47 | Since there are no arcs as well as no patches to be merged, edges and mergePatchPairs can be kept empty. |
| 02:56 | Now close this. |
| 02:58 | In the command terminal, type : cd (space) .. (dot) (dot) and press Enter. |
| 03:04 | Do this twice. You will come back to the cavity folder. |
| 03:09 | Now, type cd (space) system and press Enter. |
| 03:15 | Now type "ls", press Enter. This contains three files- |
| 03:22 | controlDict, fvSchemes and fvSolutions. |
| 03:26 | controlDict contains control parameters for start/end time.
|
| 03:30 | fvSolution contains discritization schemes used in run time. |
| 03:35 | And, fvSchemes contains equation for solvers, tolerance etc. |
| 03:40 | Now, again type cd (space) (dot dot) .. and press Enter. |
| 03:46 | Now type cd ( space ) 0 (zero) and Press Enter. |
| 03:53 | Now type "ls" and press Enter. |
| 03:57 | This contains the initial values for boundary conditions like Pressure, Velocity, Temperature etc. |
| 04:03 | Now type cd ( space ) (dot dot) . . to return back to the cavity folder. |
| 04:09 | Now we need to mesh the geometry. |
| 04:11 | We are using a coarse mesh here. |
| 04:14 | Mesh the geometry by typing blockMesh in the terminal. |
| 04:18 | Now type blockMesh (Note that M here is capital) and press Enter. |
| 04:25 | The Meshing is done. |
| 04:27 | If there are some errors in the blockMesh file, it will be shown in the terminal. |
| 04:31 | To view the geometry, |
| 04:32 | type paraFoam. Note that 'F' here is capital and press Enter. |
| 04:40 | This will open the paraview window. |
| 04:44 | Now on the left hand side of the object inspector menu, click on Apply. |
| 04:49 | You can see the lid driven cavity geometry. Now close this. |
| 04:58 | Check the mesh by typing "checkMesh" in the terminal. |
| 05:04 | Note that 'M' here is capital and press Enter. |
| 05:08 | you can see the number of cells, skewness and other parameters which are associated with the mesh. |
| 05:15 | Let me switch back to the slides. |
| 05:17 | The solver we are using here is icoFoam: |
| 05:20 | icoFoam is a Transient solver for incompressible flow of newtonian fluids. |
| 05:26 | Let me switch back to the terminal. |
| 05:29 | In the terminal, type "icoFoam". |
| 05:33 | Note that 'F' here is capital and press Enter. |
| 05:37 | The Iterations running will be seen in the terminal window. |
| 05:40 | After the solving is done, type paraFoam in the terminal to view the geometry and the results. |
| 05:54 | On the left hand side of object inspector menu |
| 05:57 | click on Apply. |
| 05:58 | Now Scroll down the properties on object inspector menu. |
| 06:02 | you can see mesh parts, Volume Fields etc. |
| 06:07 | Check or uncheck these boxes in the mesh part, to view the different boundary regions of Lid driven cavity. |
| 06:15 | Now, after this, on top of the left-hand side on active variable control drop-down menu, change this from solid color to p or capital U which are the initial conditions such as pressure, velocity. |
| 06:31 | I will select capital 'U'. Now this will show you the initial condition of velocity. |
| 06:37 | On top of the paraview window, you will see the VCR control. |
| 06:44 | Click on the play button. |
| 06:47 | Now this is the final result of velocity for the lid driven cavity. |
| 06:52 | Toggle on the color legend by clicking on the top left of the active variable control menu. |
| 07:03 | This is the color legend for U velocity. |
| 07:07 | We need to validate the results obtained.
|
| 07:09 | To do this, let us plot the U and V velocity. |
| 07:12 | To do this, go to Filters scroll down > Data Analysis > Plot Over line. |
| 07:21 | Click on it. |
| 07:23 | You can see X , Y and Z axes. |
| 07:25 | Select the X & Y axis turn by turn. |
| 07:31 | I will select the X axis and click Apply. |
| 07:37 | You can see Pressure and velocity plots being plotted. |
| 07:42 | Since it is a non dimensional analysis, we need to plot the graph for u/U v/s y/L for Reynolds number =100 |
| 07:52 | To do this, in Plot Data click on the Y-axis |
| 07:58 | and click APPLY. |
| 08:01 | You can see the plot. |
| 08:03 | Now in menu bar, go to File > Save Data. |
| 08:09 | Give appropriate name to your file. |
| 08:11 | I will give this as "cavity". |
| 08:15 | The file will be saved as ".csv" (dot csv) file. |
| 08:19 | Now click OK. Again click OK. |
| 08:23 | Now go to the cavity folder of openfoam directory. |
| 08:29 | Scroll down. you can see the cavity.csv file. |
| 08:34 | Open it in Open office or LibreOffice Spreadsheet. |
| 08:39 | In the LibreOffice spreadsheet, copy the U0 (u velocity) and to the right points 1(Y-axis) columns
in another spreadsheet. |
| 08:48 | Now, divide both these columns, that is, u zero by capital U and points 1 by capital L |
| 08:59 | and plot the results in libreoffice charts option on top, in the menu bar. |
| 09:08 | Now let me switch back to the slides |
| 09:10 | Results obtained will be similar to this figure |
| 09:16 | Validate the result on a paper published on Lid Driven Cavity by : Ghia et al. (1982) and
Results obtained from Fluent |
| 09:24 | In this tutorial we learnt |
| 09:26 | File structure of Lid Driven cavity |
| 09:28 | Solved lid driven cavity. |
| 09:30 | Post-processing of solutions |
| 09:32 | And Validation |
| 09:34 | As as Assignment, |
| 09:35 | Change some parameters in the lid driven cavity |
| 09:38 | * Velocity Magnitude in the 0 folder |
| 09:41 | * Kinematic viscosity in transportPorpoerties in constant folder |
| 09:45 | And Plot results of u/U and y/L |
| 09:50 | Watch the video available at this URL: http://spoken-tutorial.org/What_is_a_Spoken_Tutorial |
| 09:54 | It summarizes the Spoken Tutorial project. |
| 09:57 | If you do not have good bandwidth, you can download and watch it. |
| 10:00 | The Spoken Tutorial Project Team |
| 10:02 | Conducts workshops using spoken tutorials |
| 10:05 | Gives certificates to those who pass an online test |
| 10:09 | For more details, please write to us at contact @spoken-tutorial.org |
| 10:15 | Spoken Tutorials are part of Talk to a Teacher project, |
| 10:18 | It is supported by the National Mission on Education through ICT, MHRD, Government of India. |
| 10:23 | More information on the same is available at the following URL link http://spoken-tutorial.org/NMEICT-Intro |
| 10:27 | This is Rahul Joshi from IIT BOMBAY signing off. |
| 10:30 | Thanks for joining |
Contributors and Content Editors
DeepaVedartham, Gaurav, Nancyvarkey, PoojaMoolya, Sandhya.np14, Sneha
