Introduction to transient turbulence modeling (RAS,LES) - Part 1

"Introduction to transient turbulence modeling (RAS,LES)" - Part 1

This material is published under the creative commons license CC BY-NC-SA (Attribution-NonCommercial-ShareAlike). If you plan to use it, please acknowledge it.

Download the blockMeshDict file here:

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This video contains auxiliary material for students at the Johannes Kepler University in Linz, Austria. Students from other universities are welcome to use it for their learning purposes.

Thanks to Gavin Tabor from the University of Exeter for his input.

This series is based upon CFD tutorials created at the Vienna University of Technology in a cooparation with Bahram Haddadi, Christian Jordan and Michael Harasek and further improved at the Johannes Kepler University in Linz, Austria.

The used OpenFOAM version was precompiled by Andras Horvath from Rheologic GmbH, you can download it here:

[DaylightDigital]

PLEASE do not stop making these, they are great!!!

[yiannis.]

Just Thank you! Your work is a great help for many people!

[nourelislamlounis]

u don't know how much u helped me man
u don't know for real :'(

[leimiao]

In openFOAM 3.*.*, the "LESProperties" and the "RASProperties" are combined in "turbulenceProperties".

[somethingsomething]

The videos are quite nice. I hope you come around to make more :).

[kennydoritos]

How did you arrive at the definition of the turbulent viscosity at 6:00? nu_tau=0.09 X k^2/epsilon

[joseomardavalosramirez]

Hi József. All your tutorials are great, best Openfoam tutorials ever. Let me ask you a question, could I to use k-omega turbulence model instead k-epsillon?

[sumitzanje]

If we want to use the DNS model for the same configuration, how to modify (or build new) case file for it?


Please suggest how to use the DNS turbulence model so that we can compare it with the RANS and LES model.

[cartoonsindia]

kindly make video for internal compressible gas flow turbulence modelling

[oscar]

Hi József,

I want to simulate the flow of a seminfinite 2D domain which corresponds to a horizontal wall moving in the horizontal x-direction. In practice the fluid extends infinitely far away in positive/negative x-direction and positive y-direction. The initial conditions are such that the fluid is at rest and then the plate is started from rest. The pressure should be atmospheric everywhere from the start as well. What are the appropriate boundary conditions for the velocity, pressure on my 'top' and 'inlet' 'outlet' faces? If I where to use a Smagorinsky model what would be the appropriate boundary conditions for NuSgs?

many thanks,

Oscar

[yumengwang]

Hi I want to know is there similar paper, which the parameter of the BC and domain size almost identical with the video

[pingchang]

Hi Jozsef Nagy, ,
Firstly, thanks for your videos, really helpful. And I have two questions about fvsolution.In fvsolution, tolerance is already exist to control the convergence of the equation, why OF set relTol to control convergence .

And I found the value of reTol are varies in many cases. Could you tell me the reason of this?

Thanks a lot.

[simonedebellis]

Hi Jòzsef, I have a problem: I'm doing a CFD simulation around a NACA profile of 0.055 m that is in an air flow at the velocity of 25 m/s on x axis using the model K- omega, but I don't how can I estimate the values of K and omega...
What values would you insert?
Thanks.

Simone

[sumitzanje]

What about y+ value? If we are comparing different turbulence models such as k-Omega, k-epsilon, realizable k--epsilon, SST k -omega, etc. Do we need to check y+ value in each case?

Do we need to check even after using wall functions? please clarify on this.

[filippopagnoni]

Hi József, great video !
Just a little question, why for nuSGS u compute k using the deviatoric part of symm(gradU) tensor? Normally, would not be sufficient to evaluate the magnitude of symm(gradU) in your formula (slide at 8':51'') ? Thank you in advance for your really helpful videos!
Filippo

[killua]

Can we have a 2D mesh for LES cases? I always find people use 3D and I don't know why!

[michaelvillame]

Hello Prof., when I run your tutorial, I got this error in OpenFOAM 7, and I don't know why. any ideas??

--> FOAM FATAL ERROR:
Attempt to cast type zeroGradient to type nutWallFunction

[ashishtiwari]

I am looking for implementation of k-omega SST model in openfoam. Can you suggest where could i find those? And I have question related implementation of k-omega SST model. I know that theoretically k=0 at the wall but why is omega not zero at the wall?

[panittkamma]

Hi József

I saw you've slightly changed the discrete schemes in this tutorial. Now, I'm working with reacting flow problem but when I've tried to change the scheme (discrete) then the result largely changed. I've been confusing about which discrete is exactly suitable with my problem. Could you recommend about where can I find or get more knowledge to bring me out from this problem.

Thank you a lot for your help.

[McHumaty]

József.. I would like to ask if possible, make videos of 'postChannel' solver, for other non-channel geometries.