Large Eddy Simulation

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Rouaissi Ridha

Rouaissi Ridha

April 25, 2013 11:22am UTC

Large Eddy Simulation

hello
I want to use Large Eddy Simulation on comsol but I can't found it.
Can you help how to do this.

thanks a lot

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Ivar Kjelberg

Ivar Kjelberg

April 25, 2013 12:13pm UTC in response to Rouaissi Ridha

Re: Large Eddy Simulation

Hi

I'm not sure there are an "Large" Eddy current, but try out the MEF physics and the related model library cases

--
Good luck
Ivar

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Jens Krause

Jens Krause

April 25, 2013 1:55pm UTC in response to Ivar Kjelberg

Re: Large Eddy Simulation

Hi,

I think the question is about fluid dynamics. Large eddy simulation is somkething
like "direct numerical simulation" where the plain Navier-Stokes equations are solved
in turbulent regime and the eddies are resolved in space and time. In contrast
to ke-model.

Usually done in dedicated solvers, so I dont know if this can be done in Comsol.

Regards

Jens

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Ivar Kjelberg

Ivar Kjelberg

April 26, 2013 5:52am UTC in response to Jens Krause

Re: Large Eddy Simulation

Hi

sorry I misunderstood as there are different Eddy currents around ;)
For that one I'm not competent enough, have you tried to ask COMSOL directly ?

--
Good luck
Ivar

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Steve Conrad

Steve Conrad

May 16, 2013 3:22am UTC in response to Ivar Kjelberg

Re: Large Eddy Simulation

COMSOL does not have an LES study type at this time. To approximate this type of simulation in COMSOL, one can use a combination of NS equations on a fine mesh, a transient solver with small time steps (small CFL number), superimposed small random inlet variation (and perhaps asymmetry in the mesh) and time-averaging of results.

--
Steven Conrad, MD PhD
LSU Health

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Xinhui Zhou

Xinhui Zhou

May 28, 2013 3:44pm UTC in response to Steve Conrad

Re: Large Eddy Simulation

Dear Steven,

Do you have any example model to demonstrate this ? If yes, can you share it with us ? Thanks a lot. I am trying to run some simulation which requires LES turbulence model, but COMSOL does not have it.

Best,

Xinhui,.

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liu meng jie

liu meng jie

September 18, 2014 3:23am UTC in response to Steve Conrad

Re: Large Eddy Simulation

Hi
Dear Steve Conrad, you say :"COMSOL does not have an LES study type at this time". I want to know what's your meaning about "LES study type"? you know comsol using the RANS . So, can we create a LES model using it‘s equations interface or through physical Model Builder?

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Regards

Meng Jie

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Steve Conrad

Steve Conrad

September 22, 2014 12:57am UTC in response to liu meng jie

Re: Large Eddy Simulation

Meng,

COMSOL can perform standard Navier-Stokes (NS) as well as several RANS-based turbulence models (i.e. you can select a study type for each of these). The RANS-based study types are quite different from large eddy simulation (LES), which solves for large eddies instead of averaging them, and accounts for small eddies implicitly. However COMSOL does not (yet) have a separate study type for LES. Hopefully in a future release they will.

Direct numerical simulation is another approach to turbulence by directly solving the standard NS equations on a spatial scale that can resolve even the small eddies, but is usually too computationally intensive due to the need for such a superfine mesh.

I hope this answers your question.

--
Steven Conrad, MD PhD
LSU Health

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