Re: [Gfs-users] [Gfs-devel] Turbulence modelling

[Haavard H. <haa...@nt...>]

Hello,

 It is very appealing  that you can  implement the model in the 
parameter file.
The shear-improved model, is it the model that was first tested by  E. 
Leveque et. al, JFM/2007/vol 570/491-502 ?
Seems like we want to use the same case for validation. Can you release 
your parameter file with
the turbulence model included ?

Best regards

Håvard Holm

Stephane Popinet wrote:
> Hi Haavard,
>
>   
>> I do not know the code very well. Is the diffusive terms calculated by 
>> using the second
>> derivative of the velocity, or the first derivative of the stress tensor 
>> ? Answer to such
>> questions may give a hint of how much work it will be to implement the 
>> model.
>>     
>
> We have been working quite a bit on turbulence models here at NIWA in
> the past few months. We have mainly focused on LES Smagorinsky and
> shear-improved Smagorinsky. The implementation is relatively simple and
> can be done entirely within the parameter files.
>
> The difficulty is more one of model validation. This is not specific to
> Gerris however. We have been testing the model on turbulent channel flow
> and this seems to give reasonable answers but is very computationally
> expensive: long runtimes are needed to gather meaningful turbulence
> statistics etc...
>
> As with any turbulence model, you will need to consider exactly which
> type of flow you are interested in. You cannot expect that a given model
> working well in a given situation will work well in another etc... i.e.
> we really do not know how to model turbulence...
>
> Depending on your area of application, LES may also not be what you are
> after e.g. RANS with k-e model may be.
>
> hope this helps somewhat
>
> Stephane
>
>
>
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