[rajeshkunwar]

Hi Pooyan,

Can you please post the code, which you added in createField.H and pisoFoam.C

[juanma]

Originally Posted by sam1364

I also want to calculate U*U and get the average of this field over time. U is given by OpenFoam. I just need to add some lines to calculate U*U. if U=[1 2 3;4 5 6], by U*U, I mean the result is [1 4 9;16 25 36]. I do not know how openfoam writes U field so that I can write a "for loop" to calculate U*U. do you have any suggestions?

I guess you did already get the U² field... in any case here is my solution... inside createFields:

volSymmTensorField U2 = sqr(U);


Hope it helps,
Juanma

[luuhoangthien]

Dear Foamer,

I Have read and do step by step with this guide, and read carefully this topic, but went I do it have some problem,

I used dynOneEqEddy for my simulation

Any one can help me

Originally Posted by morard

Hi,

first, just copy original pisoFoam and change name to, as you said, pisoFoam2 (but, my suggestion is to choose something other like pisoRFoam, because after some tome you will have pisoFoam2, pisoFoam3,... and you will definitely forget what did you change in each of those..). So, you have to change pisoFoam.C to pisoFoam2.C. Than, open Make folder and inside files, you also have to change:

pisoFoam2.C

EXE = $(FOAM_APPBIN)/pisoFoam2

Then navigate your terminal to pisoFoam2 folder and execute:

wclean
wmake

now you have your own solver pisoFoam2. Now do the changes mentioned by Gregor and me.

If you take a look into createFields.H, you will see how pointer is created. At the end of the file it is written:

autoPtr<incompressible::turbulenceModel> turbulence
(
incompressible::turbulenceModel::New(U, phi, laminarTransport)
);

so, you'll have to put inside pisoFoam2.C

R_ = turbulence->R();

Put this inside while loop. Between the lines: turbulence->correct(); and runTime.write(); might be a good position. So, at the end you'll have:

turbulence->correct();

R_ = turbulence->R();

runTime.write();

This should wor.

Check this page:
http://openfoamwiki.net/index.php/Ho...ure_to_icoFoam

There you can find a lot of useful things.

[syavash]

Originally Posted by morard

Ufff, sorry, my mistake. It's LES about (from the first post).
So, it's definitely:

yourTurbulenceModel->B() (for LES)

Dear morard,

I know this post is old but I have a relevant question. I am using a LES model but I cannot find where B() is calculated from k in the source code. Should I add some lines to calculate B()?!

Regards,
Syavash

[syavash]

Originally Posted by luuhoangthien

Dear Foamer,

I Have read and do step by step with this guide, and read carefully this topic, but went I do it have some problem,

I used dynOneEqEddy for my simulation

Any one can help me

Hi ThienMa,

Could you find a way to solve your problem?! My case is similar to you, I also need to calculate total Reynolds stress in my LES simulation but cannot find calculation of B() in the source code of LES model.

Thanks,
Syavash

[syavash]

Originally Posted by eugene

You guys are making a mistake. Calling "R()" for an SGS model will not return the total Reynolds stress. It will just return the SGS stress. The only reason it is called "R()" is for compatibility with the RANS model nomenclature.

UPrime2Mean is calculated as:

UPrime2Mean_new = alpha*UPrime2Mean_old + (1-alpha) * sqr(U) - sqr(Umean);

with alpha = (Time - dTime) / Time

If you work it out, this is identical to the definition for Reynolds stress when averaged over a long time (<UU>-<U><U>).

To get the full stresses (resolved + SGS) you thus need UPrime2Mean + RMean. Unfortunately, you will still have to modify a solver to create RMean since the R field is not available by default as noted below.

Dear Eugen,

I am struggling to modify my solver to account for total Reynolds stress as you suggested, but I cannot find where in the source code B() (SGS stress) is calculated?!
Should I manually add some lines to the source code of LES model?!

Thanks,
Syavash

[zhangyan]

Originally Posted by buct11019

Nice to meet you , Tarak.
Now I have the same question of you had last year. I am confusing about how to set the k. I had done some work in backward step simulation with oneeqEddy and dynamicOneeqEddy model at the same grid and the same condition. I set k as 1*10-5 in both simulaiton, but the dynamicOneeqEddy model diverge after about 15s, but can go on to compute.Would you please give me some suggestion on it？

Hi
I also want to know how to set the inlet k in kEqn SGS model.
Can anyone give me a hint?

[syavash]

Originally Posted by zhangyan

Hi
I also want to know how to set the inlet k in kEqn SGS model.
Can anyone give me a hint?

Good question, Not much said in the literature.

[zhangyan]

Originally Posted by syavash

Good question, Not much said in the literature.

A reference: Reg. LES in OpenFOAM

[syavash]

Originally Posted by zhangyan

A reference: Reg. LES in OpenFOAM

Thanks, but not very helpful. It has spoken of a experimental data prior to simulation which has to be filtered out. Not in every simulation an experimental data would be available.