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

Title of script: Creating simple geometry in OpenFOAM

Author: Rahul Ashok Joshi

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

Visual Cue	Narration
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
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 of the previous tutorial as an example. Recall the path for the earlier tutorial, I have already opened the command terminal and entered the path for lid driven cavity
In the command terminal constant>>polyMesh	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 This contains the geometry file called as blockMeshDict
Open the blockMeshDict file type gedit 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
	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
Slide : About spoken tutorials	Watch 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.
Slide : about spoken tutorials	The Spoken Tutorial Project Team -Conducts workshops using spoken tutorials -Gives certificates to those who pass an online test -For more details, please write to us at contact@spoken-tutorial.org
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 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, Nancyvarkey, Rahuljoshi