Difference between revisions of "OpenFOAM/C2/2D-Laminar-Flow-in-a-channel/English-timed"
From Script | Spoken-Tutorial
(Created page with "One line is said twice @08:35 {|border=1 | '''Time''' | '''Narration''' |- | 00:01 | Hello and welcome to the spoken tutorial on ''' Simulating 2D Laminar Flow in a Channel u...") |
|||
| Line 1: | Line 1: | ||
| − | |||
{|border=1 | {|border=1 | ||
| '''Time''' | | '''Time''' | ||
Revision as of 18:00, 7 December 2015
| Time | Narration |
| 00:01 | Hello and welcome to the spoken tutorial on Simulating 2D Laminar Flow in a Channel using openfoam |
| 00:09 | In this tutorial I will show you
2D geometry of channel Meshing the Geometry Solving and Post Processing results in Paraview and Validation using analytic result |
| 00:25 | To record this tutorial I am using Linux Operating system Ubuntu 12.04 .
OpenFOAM version 2.1.1 ParaView version 3.12.0 |
| 00:39 | Note that OpenFOAM version 2.1.1 is supported on ubuntu version 12.04 |
| 00:45 | Hence forth all the tutorials will be covered using OpenFOAM version 2.1.1 and ubuntu version 12.04 |
| 00:56 | As a Pre-requisite for this tutorial You should know how to create geometry using OpenFOAM |
| 01:03 | If not, please refer to the relevant tutorials on our website |
| 01:09 | we simulate flow in a channel to determine flow development length along the downstream Channel flow problem description |
| 01:19 | The boundary names and the inlet conditions are shown in this figure |
| 01:26 | The flow develpoment length is given by the formula L= 0.05 * Re * D |
| 01:32 | Re which is the Reynolds number and D which is the channel height |
| 01:37 | Using the formula length of the channel comes out to be 5 meters and height is kept as 1 meter. |
| 01:45 | The Inlet velocity is 1 meters per second And we are solving this for a Reynolds number ( Re ) equal 100 |
| 01:53 | This is a steady state problem .Therefore we are using a steady state incompressible solver for this case |
| 02:01 | This is the file structure of our case the folder should be created in the solver type that we choose I have already created a folder in simpleFoam folder of incompressible flow solvers |
| 02:18 | The folder is named as channelNow let me switch to the folder |
| 02:25 | Copy 0,Constant and System folders of any other case file in the simpleFoam directory |
| 02:34 | I have copied the file structure of the case of pitzDaily |
| 02:38 | Paste it inside the channel folder and make the necessary changes in the geometry,boundary faces and boundary condition |
| 02:48 | Now let me open the command terminal |
| 02:51 | To do this press Ctrl+Alt +t keys simultaneously on your keyboard |
| 02:57 | In the terminal Type run and press enter |
| 03:01 | now type cd space tutorials and press enter |
| 03:08 | now type cd space incompressible and press enter |
| 03:15 | type cd space simpleFoam and press enter |
| 03:20 | now type cd channel and press enter |
| 03:28 | now type ls and press enter |
| 03:33 | You will see three folders 0 , Constant and System |
| 03:37 | now type cd constant and press enter |
| 03:48 | now type ls and press enter |
| 03:52 | In this you will see files containing properties of fluid and a folder named polymesh |
| 03:59 | RASProperties contains Reynolds-averaged stress model |
| 04:03 | transportProperties contain the transport model and kinematic viscosity that is (nu) in this case is set at 0.001 m²/s. |
| 04:17 | Now in terminal type cd polyMesh and press enter.Now type ls and press enter |
| 04:30 | You will see the blockMeshDict file here |
| 04:33 | To open up the blockMeshDict file in the terminal type gedit blockMeshDict and press enterScroll down |
| 04:48 | The geomery is in meters so the convertTometers is set to 1 next we have defined the vertices of the channel |
| 04:59 | We have used a 100 X 100 mesh size here and cell spacing is kept as ( 1 1 1 ) |
| 05:07 | Next we have setup the boundary conditions and their types which are inlet ,outlet,top and bottom |
| 05:19 | As this is a 2D Geometry front And Back are kept as empty |
| 05:27 | Also this being a simple geometry mergePatchPair and edges are to be kept empty.Close the blockMeshDict file |
| 05:38 | In the command terminal Type cd space ..(dot dot) and press enter |
| 05:44 | Again type cd space .. (dot dot) and press enter |
| 05:49 | Now in the terminal type cd space 0 (Zero) and press enterNow Type ls and press enter |
| 05:58 | This contains the intial boundary conditions and wall functions for the channel case |
| 06:05 | It should contain various files such as epsilon ,k, nut,nuTilda which are the wall functionsand p , R and capital U
which the are initial conditions of the flow |
| 06:20 | Let me switch back to the slides |
| 06:24 | Calculate k which is the turbulent kinetic energy from the formula given in the slide |
| 06:29 | Where Ux, Uy and Uz are the velocity components in the x, y and z direction And U' ( dash ) = 0.05 times u actual |
| 06:43 | Calculate epsilon from the formula given Where epsilon is the rate of disspiation turbulent energy C mu is a constant and its value is 0.09 |
| 06:56 | And l is the length of the channel Let me minimise this |
| 07:02 | Change only the boundary names in each of the above folder |
| 07:07 | Note that the values of nut, nuTilda and R are to kept default |
| 07:13 | Rest of the files should contain initial value for each of the boundary faces |
| 07:21 | Now in the terminal Type cd (space) ..(dot dot) and press enter |
| 07:27 | There are no change to be done in the system folder |
| 07:31 | Now We need to mesh the geometry To do this In the command terminal type blockMesh and press enter |
| 07:40 | Meshing is done.Now Let me switch back to the slide |
| 07:45 | The type of solver we are using here is SimpleFoamIt is a Steady-state solver for incompressible, turbulent flow |
| 07:55 | let me minimise this |
| 07:56 | In the command terminal type simpleFoam and Press enter |
| 08:03 | Iterations running will be seen in the command terminal |
| 08:07 | Iterations running may take some time |
| 08:11 | The iterations will stop once the solution is converged or it reaches its end time value |
| 08:16 | To view the results in paraview in the terminal |
| 08:20 | type paraFoam and press enter.This will open up the paraview window |
| 08:28 | On let hand side of the paraview window click Apply.The geometry can be seen here. |
| 08:35 | On top of active variable control menu change the drop down menu from solid color to capital U |
| 08:50 | You can see the initial state of velocity magnitude at inlet.. On top of the paraview window click on theplay button of the VCR control |
| 09:00 | you can see the final value of the velocity magnitude |
| 09:07 | Also' toggle on the color legend from the left hand side top of active variable control menu'Click APPLY again |
| 09:16 | Now go to displayScroll down You can see Rescale, click on it |
| 09:24 | We can see that once the flow has fully developed it attains a maximum uniform velocity at the centerNow let me switch back to the slides |
| 09:36 | The results obtained can be validated with the analytical solution for laminar flow in achannel which is u(max)=1.5 Uavg |
| 09:46 | Using openfoam we obatain a velocity of 1.48 meters per second which is a good match.This brings us to the end of the tutorial |
| 09:57 | In this tutorial we learnt The File structure of channel
Obtained solution using steady state solver Viewed the geometry in paraview 'Validation' with analytic results |
| 10:08 | As an assignment
Solve the problem for Reynold Number 1500 and validate it with the analytical result |
| 10:17 | 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. |
| 10:28 | 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 |
| 10:42 | 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. |
| 10:52 | More information on the same is available at the following URL link http://spoken-tutorial.org/NMEICT-Intro |
| 10:57 | This is Rahul Joshi from IIT BOMBAY signing off.Thanks for joining |
