OpenFOAM/C2/Simulating-flow-in-a-Lid-Driven-Cavity/English-timed

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 results 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 an assignment,
09:35	Change some parameters in the lid driven cavity.
09:38	Velocity Magnitude in the 0 folder.
09:41	Kinematic viscosity in transport Properties 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:
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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: 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