Difference between revisions of "OpenFOAM/C3/Turbulent-Flow-in-a-Lid-driven-Cavity/English"

Learning Objectives

• Solving turbulent case in OpenFOAM and
• Plotting streamlines in ParaView

System Requirement

• Linux operating system Ubuntu version 12.04
• OpenFoam version 2.1.1 and
• ParaView version 3.12.0

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

Prerequisites

• Turbulence modelling
• Knowledge of how to solve flow in a Lid driven cavity
• If not so please refer to the relevant tutorial on our website

Set up working Directory

Please make a note this problem is already set up in pisoFoam solver in OpenFoam directory

The boundary conditions are the Lid velocity U is 1 m/s

And we are solving this for a Reynolds number Re equal to 10000

Type cd tutorials

Now type cd space tutorials and press Enter

Two Folders les and ras

Cavity folder inside RAS

In this you will see two folders les and ras

Our problem setup is inside ras folder which is called as reynolds averaged stress

ls

Now type cd space ras and press Enter

Now type ls and press Enter

ls

Now type cd space cavity and press Enter

Now type ls and press Enter

Boundary and Initial conditions

0 folder

The initial conditions are specified within the files in the '0' directory

Now let us take a look at the files in the '0' directory

Type ls

Now type ls and press Enter

These files are to be kept as default until the inlet parameters don't change

If any changes are to be done please refer to the tutorial on Simulating flow in a channel using OpenFoam, to calculate these values

Let me clear this off

Type ls

To do this type cd space constant and press Enter

Now type ls and press Enter

• the geometry of the case inside blockMeshDict
• and the fluid properties

Let us open these two files

Scroll down

RASProperties contain the Reynolds average stress model for this case, which is kept as kEpsilon

Close this

Scroll down

The simulation type model for this case is kept as RASModel

Close this

Change the value of viscosity

To do this, in the terminal type gedit space transportProperties and press Enter

The transportModel we are using here is Newtonian and the Viscosity is kept as 1 e raise to -4

Close this

The system folder is to be kept default

So we need not go inside the polyMesh folder and look at the blockMeshDict file

It can be kept as it is

We will keep the system folder default as there are no changes inside it

blockMesh

Meshing is done

We can mesh the geometry

To do this in the terminal window type blockMesh and press Enter

Meshing has been done

To do this in the terminal type pisoFoam and press Enter

The iterations running can be seen in the terminal window

It may take some time for the iterations to stop

To visualize the results let us open the ParaView window

To do this in the terminal type paraFoam and press Enter

This will open the ParaView window

Lid driven cavity geometry

Change the drop down menu from solid color to U

You can see the lid driven cavity geometry

A common visualization is surface plots

Change the display to Surface in the column and from the drop down menu change from solid colour to capital U

You can see the initial condition of velocity

Toggle on the color legend

Click on the Play button

You can see the motion of the fluid inside the cavity

You can also toggle on the colour legend from the left hand side top of ParaView active variable control menu

Click on it. You can see the colour legend

Filters > Common > Stream Tracers

• On top of the menu bar of ParaView
• Go to Filters > Common and Stream Tracer
• Click on it

You can see the stream lines at the centre of the lid driven cavity

To do this , scroll down

You can see the seed type

Click on the Y axis

Click on the X axis

Delete this

Select any of these axis in which you would like to view the stream lines

I will select the Y axis and click Apply

You can see the streamlines along the Y axis

Similarly you can select the X axis and plot the streamlines along the X axis

Now delete this

Save as .csv format

To do this go to Filter > Data Analysis and Plot over line

Save the data as dot csv file from the file menu

Click on Save Data

Validate the results with Ghia et.al.

For Re= 10000

Now let me switch back to the slides

The results obtained can be validated by using results of Ghia et.al for Reynolds Number , Re equal to 10000

Summary

Let us summarise.

• Turbulent Flow in a Lid Driven Cavity
• and plotting stream lines in ParaView

This brings us to the end of the tutorial

• Modify the grid size of the cavity

• Change it to 100 100 1

• And visualise the results in ParaView using streamlines

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