View source for OpenFOAM-version-7/C2/Setting-up-a-Test-Case-in-OpenFOAM/English-timed


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|| '''Time'''
|| '''Narration'''
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|| 00:01
|| Hello and welcome to this tutorial on '''Setting up a test case in OpenFOAM'''.

|- 
|| 00:07
|| In this tutorial, we will learn to:

Set up a '''case''' in '''OpenFOAM'''

|- 
|| 00:13
||  Access the '''case files''' using '''terminal'''

|- 
|| 00:17
||  '''Pre-process''' a '''case'''

|- 
|| 00:20
||  '''Run''' a '''case''', and  '''Post-process''' a '''case'''
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|| 00:25
|| This tutorial is recorded using,

'''Ubuntu Linux''' OS version 18.04

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|| 00:34
||  '''OpenFOAM''' version 7

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|| 00:37
||  '''ParaView''' version 5.6.0, and  '''gedit Text editor'''

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|| 00:45
|| You may use any other '''text editor''' of your choice.
|- 
|| 00:50
|| As a prerequisite:  You should be familiar with basic '''Linux commands'''.

|- 
|| 00:58
||  If not, please go through the prerequisite '''Linux '''tutorials on this website.
|- 
||01:04
|| In this tutorial, we will learn to set up the '''lid driven cavity case'''.

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|| 01:10
|| '''Lid driven cavity''' is one of the most widely used '''2D test cases''' for the validation of a '''CFD '''code.
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|| 01:19
|| This is the diagram of '''Lid Driven Cavity Flow'''.

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|| 01:24
|| It consists of 3 fixed walls and a moving top wall.
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|| 01:30
|| Open a '''terminal''' by pressing the '''Ctrl, Alt '''and''' T''' keys together.
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|| 01:37
|| Here onwards please remember to press the '''Enter''' key after typing each '''command'''.
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|| 01:44
|| Now, let’s create a '''RUN directory'''.

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|| 01:48
|| To do so, type the '''command''' as shown.
|- 
|| 01:52
|| '''Tutorial cases''' will later be copied into the '''RUN directory'''.
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|| 01:57
|| Go to the '''RUN directory''' using the '''cd command'''.

|- 
|| 02:02
|| Now our present working directory is the '''RUN directory'''.
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||02:07
|| '''OpenFOAM''' installation comes with a set of '''test cases'''.

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|| 02:12
|| The '''TUTORIALS directory''' contains these '''test cases'''. 

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|| 02:17
|| The '''Lid driven cavity case''' already exists inside the '''TUTORIALS directory'''.
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|| 02:23
|| We’ll now copy the '''Lid driven cavity case''' from the '''TUTORIALS directory''' into the '''RUN directory'''.

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|| 02:31
|| To do so, type the following '''command'''.
|- 
|| 02:36
||  The '''mesh generator''' for '''OpenFOAM''' is a utility called '''blockMesh'''.

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|| 02:42
||  The '''input dictionary''' for '''blockMesh''' utility is '''blockMeshDict'''.
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|| 02:49
|| The '''blockMeshDict''' file is located in the '''system''' folder.

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|| 02:55
|| Open the '''blockMeshDict''' file in a '''text editor'''.
|- 
|| 03:00
|| Now let’s look at the contents of the file.

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|| 03:04
|| The '''blockMeshDict''' contains details of the geometry like vertices, blocks, edges and boundaries.
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|| 03:17
|| Close the '''blockMeshDict''' file.
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|| 03:20
|| The '''0''' folder contains the '''initial''' and '''boundary conditions''' for the '''simulation'''.

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|| 03:27
|| Type the following '''command''' to move into the '''0''' folder inside the '''cavity case directory'''.
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|| 03:35
|| Type '''ls''' and press '''Enter''' to view the files in the '''0''' folder.
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|| 03:41
|| The '''0''' folder contains the '''kinematic pressure file p''' and the '''velocity file U'''.
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|| 03:49
|| Open the '''kinematic pressure file p''' in a '''text editor'''.
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|| 03:54
|| The '''p''' file contains the '''initial''' and '''boundary conditions''' of '''kinematic pressure'''.
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|| 04:01
|| The '''dimensions''' of '''kinematic pressure''' is meter squared per second squared. 
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|| 04:07
|| The '''internalField''' defines the values in the interior of the domain.
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|| 04:13
|| The initial field is set as '''0 kinematic pressure'''.

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|| 04:17
|| This field is '''uniform''' across the domain.
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|| 04:21
|| You can see that all walls are imposed with a '''zero gradient pressure boundary condition'''.
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|| 04:29
|| Let us close the '''p''' file.
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|| 04:32
|| Now open the '''velocity file U''' in a '''text editor'''.
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|| 04:37
|| The '''U file''' contains the '''initial''' and '''boundary conditions''' of '''velocity'''.
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|| 04:43
|| You can see that the moving wall is imposed with a '''velocity''' of '''1 m/s''' in the x direction.
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|| 04:52
|| Also notice that the '''no-slip condition''' is imposed on the three fixed walls.
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|| 04:59
|| Now let us close the '''U''' file.
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|| 05:02
|| We’ll go back to the '''cavity''' folder.

Type '''cd (space)(dot)(dot)'''
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|| 05:10
|| Next, we will view the '''transport properties file '''which is in the '''constant '''folder.
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|| 05:17
|| The '''transportProperties''' file contains the details of '''kinematic viscosity'''.
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|| 05:24
|| The dimensions of '''kinematic viscosity''' is meter squared per second.

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|| 05:30
|| The '''kinematic viscosity''' is defined by: '''''nu'' equals magnitude of ''U'' times ''d'' by ''Re'''''

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|| 05:41
|| where '''velocity''' is '''1 m per second'''

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|| 05:45
|| characteristic length is '''0.1 meters'''

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|| 05:50
|| The '''Reynolds number (Re)''' for the '''flow''' is taken as '''10'''.

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|| 05:55
|| The '''kinematic viscosity''' is therefore '''0.01 meter squared per second'''
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|| 06:01
|| Now let me switch back to '''transportProperties''' file.
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|| 06:05
|| The value of '''kinematic viscosity''' is indicated in the '''transportProperties''' file.
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|| 06:11
|| Close the '''transportProperties''' file.
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|| 06:14
|| To move into the '''system''' folder, type the following '''command'''.
|- 
|| 06:19
|| Type '''ls''' to view the contents of the '''system''' folder.
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|| 06:24
|| The '''system''' folder contains the following files:

'''blockMeshDict, controlDict, fvSchemes''' and '''fvSolution'''.
|- 
|| 06:37
|| The '''fvSchemes dictionary''' contains the '''finite volume discretisation schemes'''.
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|| 06:44
|| The '''fvSolution dictionary''' contains the '''linear equation solvers''' and '''tolerances'''.

|- 
|| 06:51
|| It contains other '''algorithm controls''' as well.
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|| 06:56
|| The '''controlDict dictionary''' contains the '''simulation control parameters'''. 

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|| 07:02
|| The '''dictionary''' input includes the '''control''' of '''time''' and '''reading''' and '''writing''' of the '''solution data'''.
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||07:09
|| Let’s open the '''controlDict''' file in a '''text editor'''.
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|| 07:14
|| The '''start '''and''' stop times''' and the '''time step''' for the '''run''' must be set.
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|| 07:21
|| The '''start time''' is set at '''0''' seconds.
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|| 07:25
|| The time at which the '''simulation''' stops, is specified using the '''keyword stopAt'''.

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|| 07:32
|| Here, '''stopAt''' is specified using the keyword '''endTime'''.
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|| 07:38
|| The '''endTime''' is set at '''0.5 seconds'''.

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|| 07:43
|| This means that '''simulation''' stops after '''0.5 seconds'''.
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|| 07:49
|| The value of the '''keyword deltaT''' defines the '''time step''' for the '''simulation'''.

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|| 07:56
|| The '''time step''' for the current '''simulation''' is set as '''0.005 seconds'''.

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|| 08:03
|| '''Temporal accuracy''' and '''numerical stability''' is essential while running the '''simulation'''.

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|| 08:10
|| To achieve this, a''' Courant number''' of less than 1 is required.

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|| 08:16
|| Keeping this in mind, the '''time step''' is set to '''0.005 seconds'''.

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|| 08:22
|| Please refer to the '''additional reading material''' on this tutorial page for details.

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|| 08:28
|| It mentions the steps used to calculate the '''time-step'''. 

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|| 08:33
|| '''icoFoam''' is the '''OpenFOAM solver''' used to '''simulate''' the '''lid driven cavity flow'''.

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|| 08:39
|| Close the '''controlDict''' file.
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|| 08:42
|| Go back to the '''cavity''' folder using '''cd command'''.
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|| 08:47
|| Type the '''command blockMesh''' and press '''Enter''' to '''mesh''' the geometry.

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||08:53
||The '''command''' takes input from the '''blockMeshDict dictionary''' and creates the geometry and '''meshes''' it.
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||09:01
|| The '''meshing''' is now complete.
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|| 09:04
|| The '''lid driven cavity flow''' is an '''incompressible flow'''.

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||09:09
||It is solved using the''' OpenFOAM solver icoFoam.'''

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||09:14
||To start the '''simulation''', type '''icoFoam''' in the '''terminal.''' 
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|| 09:20
|| The iterations are now complete.
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|| 09:23
|| Let us view the '''simulated''' results in '''ParaView'''.

So, type '''paraFoam''' in the '''terminal.'''
|- 
|| 09:32
|| In the '''ParaView''' window, go to the '''Properties''' tab on the left.

Then click on the green coloured '''Apply '''button.
|- 
|| 09:41
|| Go to the '''Active Variable Controls '''at the top. 

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||09:46
||Click on the '''vtkBlockColors''' dropdown and select '''U'''.

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||09:52
||Ensure that you click on the '''U''' option with a '''point icon''' and not the '''box icon''', in the dropdown.

|- 
||10:00
||The '''box icon''' would display '''contours''' without any grading.
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|| 10:04
|| The '''velocity contour''' at the start of the '''simulation''' is now displayed in the''' layout'''.
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|| 10:11
|| Let us see how the '''velocity contours''' develop through the '''simulation'''.

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||10:16
||To do so, go to the '''VCR Controls''' and click on the '''Play''' button.

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|| 10:23
|| The '''velocity contour''' at the end of the '''simulation''' is now displayed in the''' layout'''.
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|| 10:30
|| Close the '''ParaView''' window.
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|| 10:34
|| With this we have come to the end of the tutorial.

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|| 10:36
|| To summarise, in this tutorial we have learnt to:

|- 
||10:42
|| Set up a''' case''' in '''OpenFOAM'''

|- 
||10:45
|| Access the '''case files''' using '''terminal'''

|- 
||10:49
|| '''Pre-process''' a '''case'''

'''Run''' a '''case''', and

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||10:54
|| '''Post-process''' a '''case'''
|-
|| 10:57
|| The video at the following link summarises the Spoken Tutorial project.

Please download and watch it.
|-
|| 11:05
|| We conduct workshops using Spoken Tutorials and give certificates.

Please contact us.
|-
|| 11:13
|| Please post your timed queries in this forum.
|-
|| 11:17
||  Do you have any general/technical questions?

Please visit the forum given in this link.
|-
||11:24
||  The FOSSEE team coordinates solving feasible '''CFD''' problems of reasonable complexity using '''OpenFOAM'''.

|- 
||11:31
|| We give honorarium and certificates to those who do this.

|- 
||11:35
|| For more details, please visit these sites.
|- 
|| 11:39
|| The Spoken Tutorial project is supported by MHRD, Govt. of India.

The script for this tutorial is contributed by Ashley Melvin.

|- 
||11:49
||And this is Swetha Sridhar from IIT Bombay signing off.

Thank you for joining.
|-
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