CFD Online Logo CFD Online URL
Home > Forums > Software User Forums > OpenFOAM > OpenFOAM Verification & Validation

Validation of LES models

Register Blogs Members List Search Today's Posts Mark Forums Read

Like Tree7Likes

LinkBack Thread Tools Display Modes
Old   May 3, 2015, 09:04
New Member
Ashvin Chaudhari
Join Date: Aug 2011
Location: Finland
Posts: 23
Rep Power: 9
ashvinc9 is on a distinguished road
Hi Xianbei,

Sorry for my late reply. I just noticed it now.

Sure, we have made some comparison between the two solvers: rk4+projection and pisoFoam. I would encourage you to look the following two papers in order to see/learn the differences between RK-4 method and the built-in second order time integration.


- Ashvin
ashvinc9 is offline   Reply With Quote

Old   December 6, 2016, 07:12
Mukesh Adlak
Join Date: Jun 2016
Posts: 32
Rep Power: 4
Adlak is on a distinguished road
Originally Posted by ashvinc9 View Post
Dear all,

I have been running the Open channel flow simulation using wall function approach. I have done done several LES for open channel flow using different wall-functions, Sgs models, numerics, etc, and I would like to share my results for further suggestions and results corrections.

These all simulations are for relatively higher Re_tau, e.g. 7500 to 60000, and in most of the cases, the grid is really coarse. Earlier (in OF 2.0 and 2.1), I was using "nuSgsUSpaldingWallFunction" wall-function but now in the newer version of OF, it also possible to employ almost all the wall-function which are made for RANS. In my case, I have used
nuSgsUSpaldingWallFunction and nutUSpaldingWallFunction, and nutURoughWallFunction for smooth, and rough wall conditions, respectively.

The LES results for open channel flow using wall-functions are reasonably good as well as the velocity solutions agree reasonably well with the Log-law for both smooth and rough wall surfaces. Actually, in all the cases, LES velocity profile underestimate the Log-law in a near-wall region and produce a kink only for few cell centred values after the first one from the wall (please see the results in the attached file: Static_SGSModel.pdf ). I have been trying a lot in order to rid out of that kink near wall boundary but didn't find any reason for such a kink so far. I also discussed with other researcher those who use LES-wall-function approach, and they say that it is common to have a such a behaviour for few cell centred values where the velocity solution go away from the Log-law. Also, that velocity defect occurs only for few cells (or nodes) so it shouldn't be too serious problem in my opinion. Please correct me if I am wrong? Please share your ideas if you have had experienced such a behaviour of velocity using wall function in LES.

SGS model validation:
Since, the coarse grid has been used in almost all LES for open channel flow, the SGS models play important roles in the simulations, and thus, the results are very sensitive to the SGS model used.
From the open channel flow testing, it seems that one equation eddy viscosity (oneEqEddy) model gives good results for the coarse LES. I also tried standard Smagorinsky model but no improvement was observed in the near-wall agreement as well as poor agreement with Log-law compared to that of using oneEqEddy model. When using any Dynamic or Lagrangian SGS models on the same case (same grid, Re_tau, numerical schemes, averaging time, solver), the LES results are really bad, the velocity profile seems to be non-stable as well as the velocity profile is not even comparable to the Log-law.I do not know why any Dynamic or Lagrangian SGS models are not working as good as static SGS model, although they are suppose to produce better results because of the dynamic procedure of finding the model constant. I have tried, e.g. dynOneEqEddy, homogeneousDynOneEqEddy, homogeneousDynSmagorinsky and dynLagrangian SGS models on the same case. But the results are not acceptable. . The results using dynamic SGS models are attached in the file: Dynamic_SGSModel.pdf. Please find the attachments.

Does any one have idea behind this problem? Did I miss something to take into account when employing the dynamic SGS model? I appreciate your comments and suggestions.


Hi ashvin,

Can u help me to run dynamicLagrangian SGS model ? I run my case but facing following error :

incompatible dimensions for operation
[flm[0 4 -5 0 0 0 0] ] + [flm[1 1 -5 0 0 0 0] ]

From function checkMethod(const fvMatrix<Type>&, const fvMatrix<Type>&)
in file /mnt/home/SW/CFDSupportFOAM3.0/OpenFOAM-3.0.x/src/finiteVolume/lnInclude/fvMatrix.C at line 1295.

FOAM aborting

#0 Foam::error:rintStack(Foam::Ostream&) at ??:?
#1 Foam::error::abort() at ??:?
#2 void Foam::checkMethod<double>(Foam::fvMatrix<double> const&, Foam::fvMatrix<double> const&, char const*) at ??:?
#3 Foam::tmp<Foam::fvMatrix<double> > Foam:perator+<double>(Foam::tmp<Foam::fvMatrix<d ouble> > const&, Foam::tmp<Foam::fvMatrix<double> > const&) at ??:?
#4 Foam::LESModels::dynamicLagrangian<Foam::EddyDiffu sivity<Foam::ThermalDiffusivity<Foam::Compressible TurbulenceModel<Foam::fluidThermo> > > >::correct() at ??:?
#5 ? at ??:?
#6 __libc_start_main in "/lib/x86_64-linux-gnu/"
#7 ? at ??:?
Aborted (core dumped)

If u can help, it will be great for my work.
Adlak is offline   Reply With Quote

Old   September 28, 2017, 11:53
Default Validation of pressure-incremental projection scheme + dynLagrangian model
Senior Member
Santiago Lopez Castano
Join Date: Nov 2012
Posts: 160
Rep Power: 7
Santiago is on a distinguished road
Hi guys,

I just saw your discussion and I wanted to put my 2 cents on the issue. For the last month I have developed a projection method similar (see Guermond&Shen) to that of Chaudhari for the incompressible N-S equations, and as validation I run the classic channel flows with different Re. The difference of my case with oodlesChannel (or channel365) is that I drive my flow using a certain pressure gradient, not by setting some flow.

Additionally, with the risk of sparking a salty debate, its my opinion that whenever you run openFOAM without any turbulence model you should not call your results 'DNS' but more 'NO-MODEL LES'. This given the 2nd-order FV nature of the library itself, and the boundary conditions that you can impose. In fact, calling 'cyclic' boundary conditions 'periodic' carries a promise that the developers where well aware of and thus decided to call them as the former.

In any case, you'll find attached the velocity profiles and RMS of channel flows run using Re_tau=171 and Re_tau=410. In both the dynamic lagrangian model of Meneveau was used. In general results seem decent.
Attached Files
File Type: pdf vel180.pdf (9.9 KB, 21 views)
File Type: pdf RMS180.pdf (17.4 KB, 13 views)
File Type: pdf vel410.pdf (10.4 KB, 14 views)
File Type: pdf RMS410.pdf (11.3 KB, 15 views)

Last edited by Santiago; September 28, 2017 at 12:22. Reason: ChaudharI
Santiago is offline   Reply With Quote

Old   September 29, 2017, 04:16
Senior Member
Albrecht vBoetticher
Join Date: Aug 2010
Location: Zürich, Swizerland
Posts: 225
Rep Power: 11
vonboett is on a distinguished road
Tahnk you, that really helps!
vonboett is offline   Reply With Quote


les, validation

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

Similar Threads
Thread Thread Starter Forum Replies Last Post
LES and DES models for wind turbine mohammad Main CFD Forum 6 April 30, 2011 22:01
LES models: Jonathan Lemay CFX 6 March 3, 2008 06:51
LES flamelet models Simon Newbond Main CFD Forum 1 August 5, 2005 06:17
Numerical Implementation of LES Wall models dragon Main CFD Forum 2 March 14, 2005 00:53
Mixed models in LES Pradeep Main CFD Forum 4 March 28, 2003 04:56

All times are GMT -4. The time now is 04:34.