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

Tutorial: Simulating Flow in a Lid Driven Cavity.

Script and Narration : Rahul Joshi

Keywords: Video tutorial,CFD,Lid Driven Cavity,Ghia et.al.

Visual cue	Narration
Slide 1	Hello and welcome to the spoken tutorial on Simulating Flow in a Lid Driven Cavity using openfoam
Slide 2 : Learning Objectives	In this tutorial I will show you The Lid Driven Cavity file structure Meshing the Geometry Solving and post-processing results in Paraview Plotting & validating results on a spreadsheet.
Slide 3: System Requirement	To record this tutorial I am using Linux Operating system Ubuntu version 10.04 . OpenFOAM version 2.1.0 ParaView version 3.12.0
Slide 4: System Requirement	The tutorials were recorded using the versions specified in previous slide Subsequently the tutorials were edited to latest versions To install latest system requirements go to Installation Sheet
Slide 4: About Lid Driven Cavity flow	Lid driven cavity is the most widely used 2D test case for validation of a CFD code
Slide 5 : Diagram	This is diagram of Lid Driven Cavity
Slide: Boundary Conditions	The boundary conditions remain the same A moving wall and three fixedwalls
	We are solving this for Reynolds no (Re) = 100 The moving wall has a velocity of 1 meters per second
Path for lid driven cavity	The path for the Lid Driven Cavity is the same as discussed in the installation tutorial
Open a command terminal	Now Open a command terminal and
Press ctrl +Alt+t keys simultaneously on keyboard	To do this press Ctrl+Alt+t simultaneously on your keyboard
Path for lid driven cavity in terminal	In the command terminal type the path for lid driven cavity
Type run and press enter	type run and press enter
Type cd tutorials and press enter	cd (space) tutorials and Press enter
Type cd incompressible and press enter	cd (space) incompressible and Press enter
Type cd icoFoam and press enter	cd (space) icoFoam (Note that F here is capital) and Press enter
Type cd cavity	type cd (space) cavity and Press Enter
Type ls and press enter	type ls and press enter
Three folders 0, constant and system	In the file structure of cavity you will see 3 folders : 0 , constant , and system
Type cd constant	Now type cd (space) constant and press enter
Type ls and press enter	Now type ls and press enter
Constant >> polyMesh	The constant folder contains another folder named polymesh and a file describing the physical properties of fluid.
Cd polyMesh and press enter	Now type cd (space) polymesh and Press Enter Polymesh contains a file named blockMeshDict
Type ls	Now type ls and press enter
	You can see the blockMeshDict
Type gedit blockMeshDict and press enter	To view the file type gedit blockMeshDict (Note that M and D here are capital) Now press enter
	This will Open up the blockMeshDict file Let me drag this to the capture area
In blockMeshDict file	This contains : -cordinates for lid driven cavity -blocking and meshing parameters -and boundary patches.
No patches and arcs in the geometry	Since there are arcs as well as no patches to be merged edges and mergePatchPairs can be kept empty
	Now close this
Terminal type cd .. and do this twice	In the command terminal type : cd (space) .. (dot) (dot)
	you will come back to the cavity folder
Cd system and press enter	Now type cd (space) system and press enter,
Type ls and press enter	Now type ls and press enter this contains three files controlDict, fvSchemes and fvSolutions
ControlDict fvSolution fvSchemes	controlDict contains control parameters for start/end time. fvSolution contains discritization schemes used in run time. fvSchemes contains equation for solver, tolerance etc.
Type cd .. and press enter	Now again type cd (space) (dot dot) . . and press enter
Cd 0 and press enter	Now type cd ( space ) 0 (zero) and Press enter
	Now type ls and press enter
Initial values for bounary	This contains the initial values for boundary conditions like Pressure ,Velocity,Temperature etc.
Type cd ..	Type cd ( space ) (dot dot) . . to return to the cavity folder
Mesh the geometry	Now we need to mesh the geometry We are using a course mesh here.
	Mesh the geometry by typing blockMesh in the terminal.
In terminal type blockMesh and press enter	Now type blockMesh (Note that M here is capital) and press enter
	Meshing is done.
	If there is some error in the blockMesh file it will be shown in the terminal
Type paraFoam and press enter	To view the geometry Type paraFoam , Note that F here is capital and press enter
	This will open the paraview window
Click on apply button	Now on the left hand side of the object inspector menu click on Apply.
	You can see the lid driven cavity geometry close this
Check the mesh	Check the mesh by typing checkMesh in the terminal Note that M here is capital and press enter
After the checkMesh command	you can see the the number of cells , skewness and other parameters which are associated with the mesh
	Let me switch back to the slides.
Slide ; icoFoam	The solver we are using here is icoFoam :
	icoFoam is a Transient solver for incompressible flow of newtonian fluids
	Let me switch back to the terminal
In terminal type icoFoam and press enter	In the terminal type icoFoam Note that F here is capital and press enter
	Iterations running will be seen in the terminal window.
Type paraFoam and press enter	Once the solving is done type paraFoam in the terminal to view the geometry and the results
Click on APPLY	On the left hand side of object inspector menu click on Apply
Scroll down in object inspector menu	Now Scroll down the properties panel of the objector inspector menu for time step,regions and volume fields etc
Check or uncheck these boxes	Check or uncheck these boxes in the mesh part to view the different boundary regions of Lid driven cavity
Change from solid color to capital U initial condition I will select capital U	Now after this on top of the active variable control dropdown menu change from solid color to capital p or U which are the initial conditions such as pressure or velocity I will select capital U Now this will show you the initial condition of velocity
VCR control on top	Now on top of the paraview window you can see the VCR control Click on the play button
Final result of velocity in lid driven cavity	Now this is the final result of velocity for lid driven cavity
Toggle on the color legend	Toggle on the color legend by clicking on top left of the active variable control menu
	This is the color legend for U velocity
Validation of result	We need to validate the results obtained To do this let us plot the U and V velocity
	We need to validate the result obtained to do this let us plot the U and V velocity.
Menu > filters > data analysis > plot over line	For this Go to Filters Menu > Data Analysis > Plot Over line
	Click on it
	You can see the X , Y and Z axis
Select the X and Y axis Select the X axis	Select the X & Y axis turn by turn. I will select the X axis and click Apply
	You can see the Pressure and velocity plots being plotted
For non-dimensional analysis	Since it is a non dimensional analysis we need to plot the graph for u/U v/s y/L for Reynolds number =100
PLot data Line click Y axis and apply	To do this in Plot Data click on the Y-axis And click APPLY
Plot can be seen Go to file save data	You can see the plot In menu bar go to File > Save Data
	Give and appropriate name to your file
Give a name to the file save as .csv format	I will give this as cavity The file will be saved as .csv file
	Now click ok Again click ok
Go to the cavity folder in icoFoam cavity.csv file	Now go to the cavity folder of openfoam directory. Scroll down you can see the cavity.csv file
	Open it in Open office or LibreOffice Spreadsheet
Copy u0 and points 1 and save it another page of spreadsheet	In the libreoffice spreadsheet copy the U0 (u velocity) and to the right points1(Y-axis) columns in another spreadsheet
U/U and y/L	Now divide both these coloumns that is u zero by capital U and points 1 by capital L
PLot the results using chart option of spreadsheet	Plot the results in libreoffice charts option on top of the menu bar.
	Now let me switch back to the slides
Slide 7 : Lid Driven Cavity (OpenFOAM)	Results obtained will be similar to this figure
Slide 8: Ghia et al.(1982) & Fluent	Validate the result obtained on Lid Driven Cavity by : Ghia et al. (1982) and Results obtained from Fluent
Slide 9 Summary	In this tutorial we learnt how to install File structure of Lid Driven cavity Solved lid driven cavity. Post-processing of results Validation
Slide 10: Assignment	As as Assignment, Change some parameters in the lid driven cavity Velocity Magnitude in the 0 folder Kinematic viscosity in transportPorpoerties in constant folder Plot the results of u/U and y/L This brings us to the end of the tutorial
Slide 11 : About Spoken tutorials	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.
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Slide 13: Acknowledgement	Spoken Tutorials are part of Talk to a Teacher project, It is supported by the National Mission on Education through ICT, MHRD, Government of India. More information on the same is available at the following URL link http://spoken-tutorial.org/NMEICT-Intro
Slide 14: About the contributor	This is Rahul Joshi from IIT BOMBAY signing off. Thanks for joining

Contributors and Content Editors

Chandrika, DeepaVedartham, Nancyvarkey, Rahuljoshi