OpenFOAM/C2/Supersonic-flow-over-a-wedge/English-timed

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Time Narration
00:01 Hello and welcome to the spoken tutorial on Supersonic flow over a wedge using OpenFOAM.
00:07 In this tutorial, I will show you: * How to solve a compressible flow problem of supersonic flow over a wedge How to postprocess the results in paraView.
00:18 To record this tutorial, I am using:Linux Operating system Ubuntu version 10.04OpenFOAM version 2.1.0ParaView version 3.12.0
00:30 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
00:35 To practice this tutorial, a learner should have some basic knowledge of Compressible flows andGas Dynamics.
00:43 Let us now solve supersonic flow over a wedge using OpenFOAM and see the shock structure formed using paraview.
00:52 The problem consists of a wedge with a semi-angle of 15 degrees kept in a uniform supersonic flow.
01:00 The Inlet velocity is 5 meters per second.
01:05 The boundary conditions are set as shown in the figure.
01:10 The type of solver I am using here is rhoCentralFoam.
01:15 It is a Density-based compressible flow solver. It is based on central- upwind schemes of Kurganov and Tadmor.
01:26 Open a command terminal . To do this, press ctrl +alt+ t keys simultaneously on your keyboard.
01:33 In the command terminal, type the path for supersonic flow over a wedge.
01:40 In the terminal, type "run" and press Enter.
01:45 cd space tutorials and press Enter.cd space compressible and press Enter.cd space rhoCentralFoam and press Enter.
02:07 cd space wedge15Ma5
02:18 This is the name of the folder of supersonic flow over the wedge in rhoCentralFoam and press Enter.
02:26 Now, type "ls" and press Enter.
02:29 You will see three folders: 0, constant and system.
02:34 Now, open the blockMeshDict file. To do this,
02:39 type cd space constant and press Enter.
02:46 cd space polyMesh note that 'M' here is capital and press Enter.
02:54 Now type "ls" and press Enter. You can see the blockMeshDict file.
02:59 To view the blockMeshDict file, type gedit space blockMeshDict. Note that 'M' and 'D' here are capital, press Enter.
03:13 Let me drag this to the capture area, scroll down.
03:19 In this, you need to calculate the co-ordinates for the wedge.
03:25 This has been already calculated and set up in the problem.
03:28 The rest of the data remains the same.
03:34 In boundary patches, boundaries are set as shown in the figure.
03:38 Close blockMeshDict file.
03:41 In the command terminal, type cd space ..(dot dot) twice to return back to wedge folder.
03:50 Now open the 0 (zero) folder.
03:56 To do this, type cd space 0 and press Enter.
04:03 Type "ls" and press Enter.
04:07 This contains the initial boundary condition for pressure, velocity and Temperature.
04:15 Type cd space .. (dot dot) and press Enter. Now we need to mesh the geometry.
04:24 To do this, in the command terminal, type "blockMesh" and press Enter. Meshing has been done.
04:37 Now, to view the geometry- in the command terminal, type "paraFoam" and press Enter. This will open the paraview window.
04:50 On the left hand side of object inspector menu, click APPLY.
04:58 In this, you can see the geometry in which the rectangular section upstream changes to a wedge downstream. Close the paraview window.
05:10 Now, run the solver rhoCentralFoam.
05:16 To do this, in the command terminal, type "rhoCentralFoam" and press Enter.
05:25 The iterations running can be seen in the terminal window.
05:29 Iterations running will stop after it converges or at the end of the time steps. Now, the solving has been done.
05:39 To visualize these results, let us open the paraview window once again.
05:45 In the command terminal, type “paraFoam” and press Enter.
05:54 Again on the left hand side of object inspector menu, click APPLY.
06:01 On the left hand side top, in active variable control menu, you will see a drop-down menu showing solid color. Now, click on it and change from solid color to capital 'U'.
06:19 Now, make the color legend ON by clicking on the left hand side top of active variable control menu and make the color legend 'ON'. Click on it.
06:33 On top of the Paraview window, you can see the VCR control. Click on PLAY.
06:42 You can see the final results of U velocity.
06:47 Now, scroll down the properties in object inspector menu on the left hand side. Now click on Display besides Properties.
07:01 Scroll down and click on Rescale to Size. You can see the final value of Velocity, magnitude.
07:10 Similarly, you can select pressure. You can see the final result of pressure. Now, close the paraView window.
07:21 You can also calculate the Mach number for the flow. To do this, we can use the Openfoam utility by typing "Mach" in the command terminal.
07:31 Type Mach.
07:34 Note that 'M' here is capital and press Enter. You can see that Mach number is calculated for each time step.
07:41 Now, again open the paraview window by typing in the command terminal "paraFoam" and press Enter.
07:53 Click APPLY, scroll down. In volume fields, check the 'Ma' box and again click APPLY.
08:09 On top of the active variable control menu, click on Solid Color and change it to 'Ma'.
08:16 In the VCR control menu, again click on PLAY and make the color legend 'ON'.
08:26 You can see the Mach number in the color legend and the corresponding colours.
08:34 We notice here that when the wedge is kept in supersonic flow, it produces a shock across which the flow properties like temprature, pressure

and density drastically change.

08:48 Now, let me switch back to the slides. The solved tutorial can be validated with exact solution available in basic books of Aerodynamics by John D Anderson.
09:00 In this tutorial, we learnt: * Solving a compressible flow problem

Velocity and pressure contour for the wedge and OpenFOAM utility for calculating the Mach number.

09:11 As an Assignment, vary the wedge angle between 10 ° to 15 ° to view the shock characteristic for the flow.
09:19 This brings us to the end of the tutorial. Watch the video available at this URL: http://spoken-tutorial.org/What_is_a_Spoken_Tutorial
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10:20 This script has been contributed by Arvind M and this is Rahul Joshi from IIT Bombay, signing off. Thanks for joining.

Contributors and Content Editors

DeepaVedartham, PoojaMoolya, Pratik kamble, Sandhya.np14