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simulation whitout a U equation

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Old   June 26, 2009, 03:52
Default simulation whitout a U equation
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Sven Degner
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hi,

i write my own DES model and try next to simulate the correlation of the isotropic turbulence. But in this case I got some problems with the initial conditions.
At the moment I got the velocity conditions, the problem is how it is possible to write the other fields for my fixed velocity field , in my case p,k,epsilon?

the simple idea, solve the case without U equation till convergence and i got the matching field for my velocity field?

original oodles something like this
:
fvVectorMatrix UEqn //the velocity equation
(
fvm::ddt(U)
+ fvm::div(phi, U)
+ sgsModel->divDevBeff(U)
);

if (momentumPredictor)
{ solve(UEqn == -fvc::grad(p)); }

// --- PISO loop
for (int corr=0; corr<nCorr; corr++)
{
volScalarField rUA = 1.0/UEqn.A();

U = rUA*UEqn.H();
phi = (fvc::interpolate(U) & mesh.Sf())
+ fvc::ddtPhiCorr(rUA, U, phi); ..........................

My question now how can edit the solver to solve my problem

target: p , k , epsilon for my over the time fixed velocity field?

best regard
Sven
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Old   August 20, 2009, 05:48
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Markus Weinmann
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Hi Sven

have you solved your problem already?
In order not to solve for U, you could try to increase the tolerance on U such that U is never updated in the iteration process.

I am also interesseted in how you have generated isotropic turbulence in OF? The reason why I am asking is because I want to calibrate a hybrid RANS/LES method using isotropic turbulence. Unfortunately, I was not very successful in generating isotropic turbulence until now. Do you have any tips?

Markus
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