OpenFOAM/C2/Creating-curved-geometry-in-OpenFOAM/English

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Tutorial: Creating curved geometry in OpenFOAM.


Script and Narration: Rahul Joshi


Keywords: Video tutorial, CFD, Flow over cylinder, edges, blocks.


Visual Cue Narration
Slide 1 Hello and welcome to the spoken tutorial on creating Curved geometry in OpenFOAM
Slide 2 : Learning Objectives In this tutorial I will show you


Steps for creating a create a curved geometry in openfoam


Viewing the results in paraview

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 5:


Hover over cylinder


Hover over the geometry


Hover over blocks


break the circle into 4 parts

We will create a geometry for flow over cylinder.


Note that I am using this case just for explanation.


The cylinder is in a form of a semi circle.


Meshing is a body fitted grid.


The entire geometry is divided into blocks.


We break the semi circle into equal number of parts.


Now minimise this

Open the lid driven cavity blockMeshDict file


Hover over arcs

Open a blockMeshDict file of the previous tutorial


I have already opened it


Scroll down, for simple geometries you can see that


edges is kept empty

Now Create a new blockMeshDict file


To do this let us minimise this first

On the desktop


Right click > create document >create file

Now Right click > create document > empty file
Name this as blockMeshDict name this as blockMeshDict.


Note that M and D here are capital


Open this

Copy the blockMeshDict of Lid driven cavity file from line 0 to line

convert to meters

Now you can copy the initial few lines from the lid driven cavity upto convertTometers
Copy these lines Go up copy this upto convertToMeters
Paste in the new blockMeshDict file Copy this and paste it in the new blockMeshDict file
Change the geometry to point one to one Change the convert to meters from point one to one
Geometry is in meters As our geometry is in meters we will keep this as one
Press enter Now press enter ,


press enter again

Refer to the figure of flow over cylinder in slide 4


After this you need to enter the co-ordinates of the geometry in vertices


Note that the points should be in an ordered way starting from 0,1,2,3 etc. as shown in the figure

Type vertices after convertTometers Now type vertices in the blockMeshDict file and press enter
Insert a open bracket


Press enter

Enter the co-ordinates as shown in the diagram Now enter the co-ordinates of points as shown in the diagram.
Let me switch back to the slides
Refer to the next slide for half semi-circle For explanation I will use the right half of the semi-circle
current blockMeshDict file Enter the values for the points in the figure starting from 0


Let me switch back to the blockMeshDict file

leave some space and enter co-ordinates of point 0
Point 0 - Insert (0.5 0 0) Open close bracket and enter (0.5 (space) 0 (space) 0)
Again leave some space , open close bracket
Point 1- Insert (1 0 0) Enter co-ordinates for point 1 (1 (space) 0 (space) 0)


Press enter

leave two vertical spaces ,


press enter


again press enter

leave some space and enter co-ordinate for the point number 4
Point 4 – Insert (0.707 0.707 0) Open close bracket, enter (0.707 (space) 0.707 (space) 0)
Press enter


Leave some space


Open close bracket



Point 5 -Insert (0.353 0.353 0) Enter the co-ordinates for point 5


Enter (0.353 (space) 0.353 (space) 0), press enter

Now leave 4 vertical spaces and
Enter co-ordinates for point number 9
Vertical spaces 1 2 3 4 , again press enter


leave some space


Open close bracket

Point 9 – Insert (0 1 0) Enter (0 (space) 1 (space) 0), press enter
Leave some space


Enter co-ordinates for point number 10

Point 10 -Insert (0 0.5 0) Open close bracket (0 (space) 0.5 (space) 0) and press enter
Remaining part of the semi-circle


use the same procedure

Similarly enter the co-ordinates for remaining points in the geometry.


Insert a close bracket and put a semi-colon


Press enter


Again press enter

In blockMeshDict file type blocks Now Type blocks and press enter


Insert a open bracket and press enter

Let me switch back to the slides
Slide showing blocks Block numbers are circled as shown in the figure
Now let me switch back to the blockMeshDict file
Enter the type of block here Leave some space


Enter the type of block i.e. Hex


leave some space

Enter points for blocks Now enter the points for the blocks


Open close brackets


Leave some space

SimpleGrading (1 1 1) ths simple grading can be kept as (1 1 1)


press enter

Refer to the previous tutorial on simple geometry in openfoam For creating the blocks please refer to the tutorial


on creating simple geometry in OpenFOAM


Note that there will be more number of blocks in this example

Insert close bracket and


semi-colon


Insert a close bracket


Insert a semi-colon and press enter


Again press enter

Type edges in the next line type edges and press enter


insert a open bracket and press enter

Here you need to enter the points which are the end points of the arcs
Enter the arc points Leave some space and type arc and leave some space


Type the points which are the end points of the arc

Insert end points of the arc


From ths slide


In this insert the end points of the arc


We start with 0 5


Let me switch back to the blockMeshDict file


Enter 0 space 5

Leave some space


Insert open close bracket

In brackets enter the co-ordinate of any intermediate point in between the two arc points.


Now Let me switch back again to slides

Slide: for arcs In the figure you can see that you have to pick up a point


in between the two points.

In this geometry I have picked up right half of the circle
Slide shwoing trignometric relations

Sin(theta) and cos(theta) relations

Using simple geometric relations


you can find the co-ordinates of the intermediate point shown in the semi-circle

Repeat the above procedure for the remaining semi-circle Similarly you can repeat the procedure for rest of the semi-circle geometry
Now let me switch back to the blockMeshDict file


Now press enter

Note that there are more number of arcs in this example
Insert a close bracket


Insert a semi -colon and press enter


again press enter

In the next line after arcs


refer to the tutorial on creating simple geometry in openfoam

Enter the boundary patches after arcs


Refer to the tutorial on Simple geometry in OpenFOAM


For entering the boundary patches

Enter boundary Enter boundary


Insert open-close bracket and press enter


Again press enter

Type mergePatchPairs


P here is capital

In the next line type mergePatchPairs


Note that P here is capital

Press enter


Insert a open bracket and press enter

Since there are no patches to be merged this can be kept empty


Insert a close bracket


Insert a semi -colon and press enter

Slide :


Points for the front face in the geometry


Let me switch back to the slides


Similarly enter the co-ordinate points for the points


in the front face of unit thickness of the geometry


as shown in the figure



Press Ctrl+Alt+t keys Open a Command terminal
Type run and press enter

cd tutorials and press enter

cd basic and press enter

cd potentialFoam and press enter

cd cylinder and press enter

In the command terminal type the path for your case file
I have already set the path for the tutorial case of flow over cylinder
Type blockMesh and press enter In the terminal type blockMesh for meshing the geometry and press enter


Meshing is done

Slide: For OpenFOAM v 5.0 To open cylinder case directory, type the following in your run folder:

$cd tutorials/basic/potentialFoam/cylinder

To run Allrun script file, type:

$./Allrun

This will run blockMesh and potentialFoam commands


Type paraFoam and press enter Now Type paraFoam in the terminal


and press enter


to view the geometry

Let me drag this to the capture area
In the object inspector menu click APPLY button Now on the left side of object inspector menu click Apply


The geometry created will be seen in the paraview window

Scroll down the Object inspector menu
Check and uncheck the mesh field box Check and uncheck the Mesh field box
Demo You can see different regions of the geometry.


You can also see the wire frame of the geometry

For wireframe of the geometry


Change from surface to wireframe

On top of active variable control menu in the drop down menu


Change from Surface to wireframe

You can see the wireframe model of the geometry


close this


Let me switch back to the slides

Slide In this tutorial we learnt:

How to create a curved geometry.


How to enter points for edges in OpenFOAM


This brings us to the end of the tutorial

Slide As an Assignment


Create a geometry with inner semi-circle of radius 2 meters


and outer circle of radius 4 meters


and


View the results in paraview

Slide 8:

About Spoken tutorials

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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.

Slide 9:

About Spoken tutorials

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Slide : Forum to answer questions Do you have questions on THIS Spoken Tutorial?

Choose the minute and second where you have the question Explain your question briefly Someone from the FOSSEE team will answer them. Please visit http://forums.spoken-tutorial.org/

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Slide : Lab Migration project We coordinate migration from commercial CFD software like ANSYS to OpenFOAM

We conduct free Workshops and provide solutions to CFD Problem Statements in OpenFOAM For more details visit this site: http://cfd.fossee.in/

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Slide 10:

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

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

Contributors and Content Editors

Chandrika, DeepaVedartham, Rahuljoshi