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Title of script: Creating simple geometry in OpenFOAM

Author: Rahul Ashok Joshi

Keywords: Video Tutorial,Computational Fluid Dynamics (CFD),OpenFOAM geometry

Visual Cue
Slide 1

Hello and welcome to the spoken tutorial on creating a simple geometry in OpenFOAM
Slide 2: Learning Objective In this tutorial I will show you

How to create a simple geometry

How to view geometry in paraview

Slide 3: System Requirement To record this tutorial

I am using Linux Operating system Ubuntu 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

Only narration

run>> tutorials >> incompressible>> icoFoam >>cavity

In CFD the Pre-processing part consists of creating geometry and meshing it.

Let us take the Lid driven cavity case as an example.

I have already opened the command terminal and entered

the path for lid driven cavity

Slide 5: For OpenFOAM v 5.0 To source the OpenFOAM version 5, type:


To go to the run folder, type:


To open the cavity case directory, type:

$cd tutorials/incompressible/icoFoam/cavity/cavity

To list the contents of case directory, type:


In the command terminal


There are three folders 0,constant,and system

Geometry is inside the polymesh folder of constant

Terminal window: type cd constant In the command terminal type cd constant and press enter
Type ls Type ls and press enter

In this there is another folder called as polymesh

Type cd polyMesh type cd polymesh and press enter
Type ls type ls and press enter
Slide 6: For OpenFOAM v 5.0 To list the contents of the cavity directory, type:

$ls 0 constant system

To open the system directory, type:

$cd system

To list the contents of the system directory, type:

$ls blockMeshDict controlDict fvSchemes fvSolution

Open the blockMeshDict file

type gedit blockMeshDict

This contains the geometry file called as blockMeshDict

Open the blockMeshDict file with any editor of your choice

In the terminal type gedit blockMeshDict and press enter

Minimise the blockMeshDict file

Slides Let me switch back to the slides
Hover over the diagram In openfoam the entire geometry is broken into blocks
Block vertex starts from 0 The blocks are numbered starting from 0 as shown in the figure
For 2D geometry enter a unit thickness cell in z axis Note that in OpenFOAM for creating a 2D geometry

you need to give a a unit cell thickness value in the z-axis.

Dimension of Cavity Lid driven cavity is of length 1 and height 1

minimise the slide

Create empty file

right click >create document>empty file

On your desktop create an empty file by

right click > create document > Empty file

and name it as blockMeshDict.

(Note that M and D here are capital)

Copy data from old blockMeshDict file

upto convertToMeters

Copy the data from the original lid driven cavity blockMeshDict file

to the new blockMeshDict file form line 0 to convertTometers.

In the blockMeshDict file

type vertices

In the file type vertices and press enter
Insert ( Put the open brackets and in the next line
Start with point 0

(0 0 0) and move to positive x axis

enter (1 0 0)

Start with 0 point, in brackets enter

(0 space 0 space 0) and press enter move towards the point 1 in positive x-axis

and enter (1 space 0 space 0) and press enter

Point 2 in the x-y plane move towards point 2 in positive x-y plane and enter (1 space 1 space 0) and press enter
Point 3 in y direction enter the 3 point in positive y axis

(0 space 1 space 0 ) and press enter

Point 4 in the front face

enter (1 0 1)

enter 4 point (1 space 0 space 1) on the front face and press enter
Points 5,6,7 with unit cell thickness in z axis Similarly enter the other points with one unit value in the positive z -axis

Inert ) and ; close the bracket and insert a semicolon after it
Type blocks and insert (

Lid driven cavity is a single block

Below vertices are the blocks Insert a Open bracket and press enter

Note that Lid driven cavity is taken as a single block

Enter the vertices of block

block (0 1 2 3 4 5 6 7 ) total 8 points

Enter the points for the blocks in a clockwise sense

in brackets enter ( 0 put space after each point and enter 1 2 3 4 5 6 7 )

For multiple blocks the points will be more.

Enter grid points in x, y and z axis After this enter the grid points in the x,y,and z directions
Enter the mesh/grid size

enter ( 30 30 1)

In brackets enter (30 space 30 space 1) ,you can modify the grid when needed
Grid point in z axis is kept as 1 Grid point in z-axis can be kept as one
Enter simpleGrading value ( 1 1 1 )

insert ) and ;

Leave a space and in brackets enter the simple grading for the mesh (1 space 1 space 1)

Close the bracket and insert a semicolon and press enter

Type edges Now type edges,as this is a simple geometry edges can be kept empty
Insert ( ); Insert open and closed bracket ,put a semicolon and press enter
Boundary conditions Below edges are the boundary conditions.
Here you need to enter the boundary name for the faces
Type boundary

insert (

Type boundary and in the next line and press enter

insert a open bracket and press enter

Let me switch back to slides

Slide : Geometry In the geometry the upper wall is moving and other three walls are fixed.
Front and back faces are kept as empty The front and back faces are termed as empty as this is a 2D problem
Open the current blockMeshDict file Open the New blockMeshDict file again
Boundary patch as moving wall In boundary put the name of the patch as moving wall
Insert { Insert a open curly bracket
Type of moving wall : wall

insert ;

Enter type for the moving wall as wall and

insert a semicolon

Enter and type faces

Enter open and close brackets In brackets enter the points for faces

Let me switch to slides
Slide : Geometry Note that order the points in such a way that the thumb should be normal to that face
Clockwise curl of fingers And fingers make a clockwise curl as shown in the figure
Points should be entered matching the points inserted in vertices Also note that the points should match with the points inserted in vertices
Enter (3 7 6 2)

insert } and ;

Enter the face points as (3 space 7 space 6 space 2) as shown in the figure

Insert a curly brackets and put a semicolon.

Boundary patches for fixedWalls Similarly enter boundary condition and faces for the fixed wall
For front and back face enter type as empty Being a 2D problem the type of boundary

for front and back face can be kept empty

Insert Insert open-closed brackets and put a semicolon.
BlockMeshDict file is completed

We are done with creating the blockMeshDict file.

The complete blockMeshDict file is as shown here.

Close the original blockMeshDict file

The command terminal will not work till blockMeshDict is closed

Close the original blockMeshDict file

Note that command terminal will not work until blockMeshDict file is closed

Type cd .. twice type cd (dot) (dot) twice to return to the cavity folder Mesh the geometry
Meshing, type blockMesh in terminal type: blockMesh and press enter
Viewing the geometry type paraFoam View the geometry by typing in the command terminal paraFoam and press enter

In the object inspector menu click Apply On the left hand side click Apply on object inspector menu
Slide In this tutorial we learnt:

Creating a simple geometry in OpenFOAM

Viewed the geometry in Paraview

This brings us to the end of the tutorial

Slide : Assignment Assignment

Change the geometry parameters : Enter the grid points as (40 40 1) and (50 50 1).

View the geometry in paraview

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Slide: 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

About the contributor This is Rahul Joshi from IIT BOMBAY signing off.

Thanks for joining.

Contributors and Content Editors

Chandrika, DeepaVedartham, Rahuljoshi