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Revision as of 21:17, 17 December 2013
| 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
|
| 00:18 | 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 ParaView version 3.12.0 |
| 00:33 | Lid driven cavity is the most widely used 2D test
|
| 00:36 | case for validation of a CFD code |
| 00:39 | This is diagram of Lid Driven Cavity |
| 00:42 | The boundary conditions remain the same
|
| 00:44 | A moving wall and three fixedwalls |
| 00:47 | We are solving this for Reynolds no (Re) = 100
|
| 00:50 | The moving wall has a velocity of 1 meters 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 simultaneously on your keyboard |
| 01:08 | In the command terminal type the path for lid driven cavity |
| 01:12 | Now 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. |
| 02:02 | 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 blockMeshDictfile type gedit blockMeshDict
|
| 02:30 | This will Open up the blockMeshDict file
|
| 02:32 | Let me drag this to the capture area |
| 02:36 | This contains : cordinates for 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
|
| 02:51 | edges and mergePatchPairs can be kept empty |
| 02:57 | 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, |
| 03:16 | 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 | AndfvSchemes contains equation for solver,
|
| 03:38 | tolerance etc. |
| 03:40 | Now again type cd (space) (dot dot) . . and press enter |
| 03:47 | 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
|
| 04:00 | 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 course 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 | TheMeshing is done. |
| 04:27 | If there is some error 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 ,
|
| 05:10 | skewness and other parameters
|
| 05:12 | which are associated with the mesh |
| 05:15 | Let me switch back to the slides. |
| 05:18 | 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 |
| 05:44 | to view the geometry and the results |
| 05:54 | On the left hand side of object inspector menu
|
| 05:57 | click on Apply |
| 05:59 | Now Scroll down the properties on objector inspector menu
|
| 06:02 | you can see mesh part,volume fields etc |
| 06:07 | Check or uncheck these boxes in the mesh part
|
| 06:11 | 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
|
| 06:21 | dropdown menu change this from solid color to p orcapital U
|
| 06:26 | 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 can see the VCR control
|
| 06:44 | Click on the play button |
| 06:47 | Now this is the final result of velocity for 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 axis |
| 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
|
| 07:44 | 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 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 point 1(Y-axis) columns
|
| 08:46 | in another spreadsheet |
| 08:48 | Now divide both these coloumns
|
| 08:52 | 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 |
| 09:11 | 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
|
| 09:22 | 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 | AndValidation |
| 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
