OpenFOAM-version-7/C2/Creating-3D-Pipe-Geometry-and-Mesh-in-OpenFOAM/English

Title of the script: Creating 3D Pipe Geometry and Mesh in OpenFOAM

Author: Divyesh Variya

Keywords: OpenFOAM, 3D-Geometry, Pipe, Meshing, ParaView, Pre-Processing, Video-Tutorial, blockMesh

Visual Cue	Narration
Slide: Opening slide	Welcome to this tutorial on Creating 3D Pipe Geometry and Mesh in OpenFOAM.
Slide: Learning Objective	In this tutorial, we will learn to: Create a 3D Geometry using blockMeshDict Mesh a 3D geometry Label the boundary patches Check the mesh results using checkMesh command View the 3D geometry and mesh in ParaView
Slide: System Specifications	To record this tutorial, I am using, Ubuntu Linux OS version 18.04 OpenFOAM version 7 ParaView version 5.6.0 gedit Text editor You may use any other editor of your choice.
Slide: Prerequisites If not, please go through the prerequisite OpenFOAM tutorial on https://spoken-tutorial.org	As a prerequisite: You should be familiar with creation of a basic geometry using the blockMesh utility. If you are not, please go through the prerequisite OpenFOAM tutorial on this website.
Slide: Code Files	The files used in this tutorial are available in the Code Files link on this tutorial page Please download and extract them Make a copy and then use them while practising
Slide: Hagen Poiseuille flow through a pipe	In this tutorial, we will learn to create the geometry for Hagen Poiseuille flow through a pipe. The problem description of Hagen Poiseuille flow through a pipe is shown in the diagram.
Slide: Pipe Geometry	This is the diagram of the geometry for Hagen Poiseuille flow through a pipe. The left and right faces are the inlet and outlet respectively. The cylindrical face of the geometry is a wall. The diameter of the pipe is 1 centimeter and its length is 30 centimeters.
CTRL + ALT + T	Open the terminal by pressing Ctrl, Alt & T keys.
[Terminal] Type: cd $FOAM_RUN	At the prompt, type the following command to go to the run directory.
Only Narration	Here onwards, please remember to press the Enter key after typing each command.
[Terminal] Type: cp -r $FOAM_TUTORIALS/incompressible/icoFoam/cavity/cavity pipe	Let’s now copy the cavity case from the icoFoam tutorial directory to the run directory. Type the following command to do so.
[Terminal] Highlight: pipe	Note that the cavity case is copied to the pipe directory.
[Terminal] Type: mv pipe/0 pipe/0.Orig	In this tutorial we don’t need to define initial and boundary conditions in zero time. Type this command to rename “0” folder to “0.Orig”
[Terminal] Type: gedit pipe/system/blockMeshDict	The blockMeshDict file is located in the system folder. Open this file in a text editor. I am doing it in the gedit text editor.
[gedit - blockMeshDict]	Now we can see the blockMeshDict file in the text editor.
[gedit - blockMeshDict] Highlight Selection in the Text Editor >> Delete	Delete the lines from convertToMeters to the end of the file as shown here. The remaining content is common for all blockMeshDict files.
[gedit - pipe]	Next, open the pipe.txt file that you had downloaded in the text editor.
[gedit - blockMeshDict] Highlight Selection in the Text Editor >> Copy	Copy the entire content of the text file.
[gedit - blockMeshDict]	Now switch back to the blockMeshDict file.
[gedit - blockMeshDict] Paste	And paste the copied contents into the blockMeshDict file as shown.
[gedit - blockMeshDict] Highlight 0.01	Note that all the dimensions will be in centimeters.
Slide: Vertices Detail	Vertices are shown in the slide. Here we are going to use 18 vertices to define the geometry of a pipe. For example, two reference points 0 and 17 are on (0 0 0) and (0 0 30) respectively.
[gedit - blockMeshDict] Highlight Selection in the Text Editor >> vertices	All 18 points are defined in the vertices section in the blockMeshDict file as shown.
Only Narration	Now let me switch back to the Slides.
Slide: Block Detail	Here we will use 5 hexahedral blocks to define the pipe geometry. As you can see, the center hexahedral block is separately shown in the figure on the right. To define this block, we need to type the back plane’s vertices first. The vertices should be ordered anti-clockwise when viewed along the negative z-axis. The front plane’s vertices should also follow the same order.
Slide: Block Detail Highlight: hex (1 2 3 4 9 10 11 12) (8 8 80) simpleGrading (1 1 1)	An example is shown in the slide. The same block can be defined correctly in more than one way.
Slide: Block Detail Highlight: (8 8 80)	To generate 3D mesh we are using: 8 cells in X direction, 8 cells in Y direction and 80 cells in Z direction.
[gedit - blockMeshDict] Highlight Selection in the Text Editor >> blocks	Other 4 blocks are defined in the blockMeshDict file as shown.
Slide: Geometry Arc Detail	For the curved geometry, we need to define the edges.
Slide: Geometry Arc Detail	There are a total of 16 arcs that we need to define. The arcs and the intermediate points are shown in the slide. Note that I have used the midpoint of the arc as the intermediate point. However, any other point through which the arc passes is acceptable.
Slide: Geometry Arc Detail Highlight: arc 5 6 (0 0.5 0)	For example, the edge from Point number 5 to 6 is passing through (0 0.5 0).
[gedit - blockMeshDict] Highlight Selection in the Text Editor >> edges	All 16 arcs are defined in the edges section in the blockMeshDict file as shown.
[gedit - blockMeshDict] Highlight arc 5 6 (0 0.5 0)	The curved edge connecting points 5 and 6 is defined as shown.
[gedit - blockMeshDict] Highlight arc	The edge is an arc.
[gedit - blockMeshDict] Highlight 5 6	Its two end points are 5 and 6.
[gedit - blockMeshDict] Highlight (0 0.5 0)	The coordinates of the point through which the arc passes through is 0, 0.5, 0
Only Narration	Let’s label the boundary patches. The boundary faces should be labelled appropriately. The labels are used to impose boundary conditions on the respective faces.
[gedit - blockMeshDict] Highlight Selection in the Text Editor >> inlet	The inlet boundary is defined as shown.
[gedit - blockMeshDict] Highlight Selection in the Text Editor >>	The inlet boundary has 5 faces. These faces are defined as shown.
[gedit - blockMeshDict] Highlight Selection in the Text Editor >> outlet and wall	The outlet and wall boundary is defined as shown.
Only Narration	Note that all boundaries have more than one face.
[gedit - blockMeshDict] Highlight Selection in the Text Editor >> mergePatchPairs	We do not have any patches or internal faces to merge. Therefore, we leave the mergePatchPairs field empty.
CTRL+S >> Close Text Editor	Now, save the blockMeshDict file and close the text editor.
[Terminal] Type: cd pipe	Now, go to the terminal and navigate to the pipe directory.
[Terminal] Type: blockMesh	Type blockMesh command and press Enter.
[Terminal] Highlight End	The meshing is now complete.
[Terminal] Highlight Patches section	As we can see in terminal results, three patches are created.
[Terminal] Type: checkMesh	Now, let’s check mesh results and quality. To do that type checkMesh in the terminal and press Enter. Note that M in checkMesh is capital.
Only Narration	We get the results printed of the mesh we created.
[Terminal] Highlight Max skewness = 0.6954 OK. Non-orthogonality check OK. Max aspect ratio = 30.3404 OK. Overall domain bounding box	Here we can see: Skewness Orthogonality Aspect ratio Negative volume values if they are present In our case, no negative volume is present. Bounding box coordinates and
[Terminal] Highlight Overall number of cells of each type: hexahedra: 25600 prisms: 0 wedges: 0 pyramids: 0 tet wedges:0 tetrahedra:0 polyhedra: 0	Number of cells with their types
[Terminal] Type paraFoam	To view mesh in paraview type paraFoam and press Enter.
[ParaView] Click Apply	Click on Apply on the left side of your window in the Properties tab. Now you can see pipe geometry in the Layout window.
[ParaView] Rotate geometry	You can rotate geometry in the Layout window by pressing the left mouse button and dragging.
[ParaView] Click on Surface >> Click on Surface with Edges	Click on Surface available in the Active Variable Controls. Then change it to Surface with Edges.
[ParaView] Click on vtkBlockColors >> SolidColor	Click on vtkBlockColors available in the Active Variable Controls. and change it to SolidColor. You can now see the mesh structure of pipe geometry that we created.
[ParaView] Close ParaView	You can close the ParaView window.
Only Narration	With this we have come to the end of the tutorial. Let’s summarize.
Slide: Summary	In this tutorial, we have learnt to, Create a 3D Geometry using blockMeshDict Mesh a 3D geometry Label the boundary patches Check the mesh results using checkMesh command View the 3D geometry and mesh in ParaView
Slide: About the Spoken Tutorial Project	The video at the following link summarises the Spoken Tutorial project. Please download and watch it.
Slide: Spoken Tutorial Workshops	We conduct workshops using Spoken Tutorials and give certificates. Please contact us.
Slide: Spoken Tutorial Forum	Please post your timed queries in this forum.
Slide: FOSSEE Forum	Do you have any general/technical questions? Please visit the forum given in the link.
Slide: FOSSEE Case Study Project	The FOSSEE team coordinates solving feasible CFD problems of reasonable complexity using OpenFOAM. We give honorarium and certificates to those who do this. For more details, please visit these sites.
Slide: Spoken Tutorial	The Spoken Tutorial project is supported by MHRD, Govt. of India. The script for this tutorial is contributed by Divyesh Variya. And this is Swetha Sridhar from IIT Bombay signing off. Thanks for joining.

Contributors and Content Editors

Divyesh7, Nancyvarkey