Difference between revisions of "OpenFOAM/C3/Flow-over-a-flat-plate/English-timed"

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| In this tutorial, I will teach you about:   * Geometry of the flat plate  
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* Geometry of the flat plate  
 
* Changing the grid spacing in '''meshing'''
 
* Changing the grid spacing in '''meshing'''
 
* Postprocessing results in '''ParaView''' and  
 
* Postprocessing results in '''ParaView''' and  

Revision as of 18:05, 28 June 2016

Time Narration
00:01 Hello and welcome to the spoken tutorial on Flow over a flat plate using OpenFOAM.
00:06 In this tutorial, I will teach you about:
  • Geometry of the flat plate
  • Changing the grid spacing in meshing
  • Postprocessing results in ParaView and
  • Visualizing using Vector Plot.
00:19 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
00:30 Flow over flat plate is a fundamental problem in fluid mechanics.
00:35 We can visualize the growth of the boundary layer. Boundary layer is a very thin region above the body
00:41 where the velocity is 0.99 times the free stream velocity.
00:46 This is a diagram of flow over the flat plate.
00:49 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.

01:00 The Free stream velocity U = 1 m/s' and we are solving this for Reynolds number (Re) = 100'.
01:08 Now let us go to the home folder. In the home folder, click on the OpenFoam folder.
01:15 Then go to the Run directory. You will see Tutorials. Click on it.

Scroll down and then click on Incompressible. Scroll down.

01:27 You will see the simpleFoam folder. Click on it. This solver suits our case.
01:34 In this, create a folder by the name flatplate. Right click - Create New Folder - flatplate.
01:44 Now, let's open the pitzdaily case.
01:47 Let me zoom this. Copy the three folders - 0, constant and system. Copy this.
01:56 Now let us go one level back. Paste these three folders inside the flatplate folder.
02:05 Open the constant folder and then the polyMesh folder.
02:10 Change the geometry and boundary condition names in the blockMeshDict file.
02:15 I have already made the changes. Let us open the blockMeshDict file . Scroll down. The geometry is in meters.
02:25 We have set the dimensions of the flatplate.
02:29 We can see the simpleGrading. It is kept as (1 3 1) as we need a finer mesh near the plate.
02:35 Now close this. Go two levels back.
02:41 Similarly, make changes in the boundary condition names inside the files in the '0' folder.
02:48 These files have pressure, velocity and wall functions.
02:54 To calculate the values of wall functions, please refer to the earlier tutorial in the OpenFoam series. Let us go one level back.
03:03 The system folder can be kept default. Let us close this.
03:09 Now let us open the terminal window. In the terminal window, type "run" and press Enter.
03:16 Type cd space tutorials press Enter.
03:21 Type cd incompressible press Enter.
03:25 Type cd space simpleFoam press Enter.
03:31 Now type "ls" and press Enter.
03:34 We can see the flatplate folder.
03:37 Now, type cd space flatplate and press Enter.
03:42 Now type "ls" and press Enter.
03:45 You can see the three folders 0, constant and system.
03:49 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.
03:58 Press Enter. Meshing has been done.
04:01 Note that if there is some error in the blockMesh file, it will be shown in the terminal window.
04:07 To view the geometry, type “paraFoam”, press Enter.
04:13 After the ParaView window opens, on the left hand side of the object inspector menu, click Apply.
04:21 We can see the geometry. Close the ParaView window. Let me switch back to the slides.
04:28 The solver we are using here is simpleFoam. SimpleFoam is a steady state solver for in compressible and turbulent flows.
04:37 Let me switch back to the terminal window. In the terminal window, type "simpleFoam" and press Enter.
04:45 You will see the iterations running in the terminal window.
04:51 Once the solving is done, type "paraFoam" to view the results.
04:55 On the left hand side of the Object Inspector menu, click Apply to view the geometry.
05:01 Scroll down the properties panel of the Object Inspector menu for time step, regions and fields.
05:08 To view the contours from the top drop down menu, in the Active Variable Control menu, change from solid color to capital 'U'.
05:19 You can see the initial condition of the velocity.
05:23 Now on top of the ParaView window, you will see the VCR control.
05:28 Click on the Play button.
05:33 You will see the contour of Pressure or Velocity on the flat plate accordingly.
05:39 This is the velocity contour. Toggle on the Color legend.
05:43 To do this, click on the color legend icon on the Active Variable Control menu.
05:50 Click Apply in the Object inspector menu.
05:53 In the Object inspector menu, click on Display.
05:57 Scroll down and click on Rescale to data range.
06:03 Let me shift this Color legend on top to visualize the Vector Plot. Go to the Filters Menu > Common > glyph.
06:15 Go to the Properties in Object Inspector menu.
06:20 Click Apply on the left hand side of Object Inspector Menu.
06:24 You can change the number of vectors by changing their size at the bottom.
06:29 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
06:41 Again, click the Apply button.
06:44 Now let me zoom this.
06:46 To do this, in the Active Variable Control menu, click on zoomToBox option.
06:52 And zoom over any area that you desire.
06:58 We can see the parabolic variation of vector plot as the flow moves over the plate.
07:04 Delete this. Now delete the vector plot.
07:09 Also, we can see that the color near to 1 corresponds to the velocity of 0.99 times the free stream velocity.
07:17 You can also plot the variation of velocity along the X and Y axes using the plot data over line.
07:26 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.
07:37 As an Assignment-

Create a geometry of flow over a flat plate. Refine the grid spacing near the plate.

07:45 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.

07:55 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: contact@spoken-tutorial.org

08:08 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.
08:17 More information on this mission is available at this URL: http://spoken-tutorial.org/NMEICT-Intro.

This is Rahul Joshi from IIT Bombay, signing off. Thanks for joining.

Contributors and Content Editors

DeepaVedartham, PoojaMoolya, Pratik kamble, Sandhya.np14