OpenFOAM/C3/Flow-over-a-flat-plate/English

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Tutorial: Flow over a flat plate using OpenFOAM.

Script and Narration: Rahul Joshi

Keywords: Video tutorial, CFD, Flat plate, Boundary layer, glyph (vector plotting).

Visual Cue Narration
Slide 1 Hello and welcome to the spoken tutorial on Flow over a flat plate using OpenFOAM
Slide 2 : Learning Objectives In this tutorial I will teach you about
  • Geometry of the flat plate
  • Changing the grid spacing in meshing
  • Post Processing results in ParaView and
  • Visualizing using Vector Plots
Slide 3:

System Requirement

To record this tutorial

I am using

  • Linux Operating system Ubuntu version 12.04
  • OpenFOAM version 2.1.1 and
  • 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: Flow over Flat Plate Flow over flat plate is a fundamental problem in fluid mechanics
Slide 6: Flow over Flat Plate

Flow over a flat plate diagram

We can visualise the growth of the boundary layer

Boundary layer is a very thin region above the body

where the velocity is 0.99 times the free stream velocity

Slide 7: Diagram of boundary conditions. This is a diagram of the flow over the flat plate

The boundary conditions are given as follows

  • You have the Inlet
  • the Plate
  • Top which is the Farfield
  • and Outlet which is the pressure outlet boundary
Slide 8: Inlet parameters
  • The Free stream velocity U is 1 m/s, and
  • we are solving this for a Reynolds number (Re) = 100
Click on home>> OpenFoam >> Run >> Tutorials >> Incompressible >> SimpleFoam Now let us Go to the Home folder, In the Home folder, click on the OpenFoam folder

Then go to the Run directory

You will see Tutorials. Click on it

Scroll down and then click on Incompressible

Scroll down

You will see the simpleFoam folder

Click on it

This solver suits our case

Right click >> Create new folder >> flatplate In this, create a folder by the name flatplate

Right click Create New Folder flatplate

Double-click pitzdaily folder Now, let us open the pitzdaily case
Zoom in Let me zoom this.
Select 0, constant and system folders Copy the three folders 0, constant and system
Copy them Copy this
Go back to SimpleFoam >> flatplate folder

Paste them there

Now let us go one level back

Paste these three folders inside the flatplate folder

Click on constant >> polyMesh Open the constant folder and then the polyMesh folder
Change the geometry and boundary condition names in the blockMeshDict file
I have already made the changes.

Let us open the blockMeshDict file . Scroll down

The geometry is in meters

We have set the dimensions of the flatplate
Simplegrading (1 3 1) You can see the simpleGrading

It is kept as (1 3 1) as we need a finer mesh near the plate

Now close this

Go two levels back

Similarly, make changes in the boundary condition names inside the files in the 0 folder

These files have pressure velocity and wall functions

To calculate the values of wall functions


please refer to the earlier tutorials in the OpenFoam series

Let us go one level back

The system folder can be kept default

Let us close this

Let us Open the terminal window :

Press Ctrl+Alt+t keys simultaneously

Now let us open the terminal window

In the terminal window, type run and press Enter

Type cd tutorials Now type cd space tutorials press' Enter
Type cd incompressible Now type cd incompressible press Enter
Type cd simpleFoam Now type cd space simpleFoam press Enter
Type ls Now type ls and press Enter
We can see the flatplate folder.
Type cd flatplate Now type cd space flatplate and press Enter
Type ls Now type ls and press Enter
You can see the three folders 0 constant and system
Type blockMesh Now, we will mesh the geometry.

We are using a course mesh for this problem

Meshing can be done by typing blockMesh in the terminal

Press Enter

Meshing has been done

Note that if there is some error in the blockMesh file

it will be shown in the terminal window

Type paraFoam To view the geometry, type “paraFoam
And press Enter
Paraview window click on APPLY button on left hand side After the ParaView window opens, on the left hand side of the object inspector menu, click Apply

We can see the geometry

Close the ParaView window

Let me switch back to the slides

Slide 9: solver The solver we are using here is simpleFoam

SimpleFoam is a steady state solver for incompressible

and turbulent flows

Demo :

type simpleFoam

Let me switch back to the terminal window

In the terminal window ,type simpleFoam and press Enter


You will see the iterations running in the terminal window

Type paraFoam Once the solving is done, type paraFoam to view the results
In the Paraview window click on APPLY button on left hand side On the left hand side of the Object Inspector menu, click Apply to view the geometry
Properties Scroll down the properties panel of the Object Inspector menu for time step, regions and fields
Change the drop down menu from Solid Color to U To view the contours from the drop down menu,

in the Active Variable Control menu,

change from solid color to capital U

You can see the initial condition of the velocity
VCR control Now on top of the ParaView window, you will see the VCR control
Click on Play button of VCR control Click on the Play button
You will see the contour of Pressure or Velocity on the flat plate accordingly
Toggle on the Color legend This is the velocity contour

Toggle on the Color legend

Color legend left hand side top icon To do this, click on the color legend icon on the Active Variable Control menu
Click on APPLY button Click Apply in the Object inspector menu
Click on Display In the Object inspector menu, click on Display
Click on rescale to data range Scroll down and click on Rescale to data range
Shift color legend on top of the geometry Let me shift this Color legend on top
Top menu >> Filter > Common > glyph To visualize the Vector Plot,

go to the Filters Menu > Common > glyph

Go to the Properties in Object Inspector menu
Click Apply on the left hand side of Object Inspector Menu
Changing vector size You can change the number of vectors by changing their size at the bottom
Scroll down and click on edit button

set scale factor 0.1

Also, the size of the vectors can be changed by clicking on the Edit button

The set scale factor can be changed to 0.1

Click the apply button Again, click the Apply button
Now let me zoom this
Click on ZoomToBox icon To do this, in the Active Variable Control menu, click on the zoomToBox option
And zoom over any area that you desire
Parabolic variation of vector plot We can see the parabolic variation of vector plots as the flow moves over the plate
Delete the vector plot Delete this. Now delete the vector plot
Corresponding to color of 1 in color legend Also, we can see that the color near to 1

corresponds to the velocity of 0.99 times the free stream velocity

To plot the data along x and y axis We can also plot the variation of velocity along the x and y axes using the plot data over line
Slide 10: Summary This brings us to the end of the tutorial

In this tutorial we learnt :

  • Geometry and meshing of the flat plate geometry and
  • Vector plotting in ParaView
Slide 11: Assignment As an Assignment,

Create a geometry of flow over the flat plate

Refine the grid spacing near the plate

Slide 12 : 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 13: Spoken Tutorial Worekshops The Spoken Tutorial Project Team

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contact(at the rate)spoken(hyphen)tutorial(dot)org

Slide 14: 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/

Slide 15: Forum to answer questions
  • Questions not related to the Spoken Tutorial?
  • Do you have general/technical questions on the Software?
  • Please visit the FOSSEE forum

http://forums.fossee.in/

  • Choose the Software and post your question
Slide 16: 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/

Slide 17: Case Study Project
  • We invite students to solve a feasible CFD problem statement of reasonable complexity using OpenFOAM
  • We give honorarium and certificate to those who do this

For more details visit this site: http://cfd.fossee.in/

Slide 18:

Acknowledgement


Spoken Tutorial project is a part of the Talk to a Teacher project,

It is supported by the National Mission on Education through ICT, MHRD, Government of India

More information on this mission is available at this URL 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

DeepaVedartham, Nancyvarkey, Rahuljoshi, Sneha