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 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 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.
02:01	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 : 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, 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 solver, 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 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	The Meshing 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, 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 objector 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 , dropdown 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 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, 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 in another spreadsheet
08:48	Now divide both these coloumns 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