CFD Online Discussion Forums - How to Initialise my LES case using my RANS case is there any utility for it ?

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How to Initialise my LES case using my RANS case is there any utility for it ?

Hey All,

Can some body tell me how to initialise one case using another case in openFOAM, say how to initialise a K-omega case using a K-epsilon case !!!! - answer to this is more than enough.

but if u know LES then actually I am trying to initialise my LES case using my RANS case i dunno where to start with, can i just copy paste my U file from the RANS case to my LES case :confused: im not sure that is right

- can somebody who has done it please tell me because my LES case without intialising the Courant number goes high and crashes :( so this is my only option and i dunno how to go about it

Thanks guys :) :)

Hasan K.J

Hi Alhasan,

I am interested in this topic too. Do you have some advices to share?

Thank you,

vut

hi,

first, run your case with RANS and then:

Quote:

- Control dict, changing simulation to pisoFoam and verify you're not going to have problems with your timeStep. I'm using a Courant Number of 0.05, with Co=0.5 my calculation diverged for instance.

- You have to change "fvSchemes" and "fvSolution" as I wrote the other day. The motorbike tutorial files work well.

- You have to add "nuSgs" and "nuTilda" to the startTime of the LES simulation which will be the endTime of the RANS simulation, and in my case I erased "nut".

- If you're running a parallel calcul you will have to add "proc.*", you can find this in the motorbike tutorial too.

- Finally, you will have to change the constant folder too. You must erase the "RASproperties" file and add "LESproperties" and "turbulenceproperties", you can find both of them again in the motorbike tutorial.

you can use mapFields if your geometry or BCs are different with your new case.