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suitable boundary condition for scavenging process? |
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#1 |
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Senior Member
Ehsan
Join Date: Oct 2012
Location: Iran
Posts: 2,208
Rep Power: 28 ![]() |
I have found the cause of errors in my simulation.its at scavenging process.
there is a tube that is filled with internalField: U=0,T=400K,p=250000pa and suddenly one side of it become open to environment.the environment has BC: p0=100000pa and T=288K. I have set various set of BC's for it but I have not obtain correct answer yet.a divergence in e calculation is occured because of decreasing T below 200K. I have examined these sets so far: 1)p:waveTransmissive T and U:zeroGradient Code:
type waveTransmissive;
field p;
phi phi;
rho rho;
psi psi;
gamma 1.4;
fieldInf 100000;
lInf .1;
value uniform 100000;
2)p:totalPressure T and U:zeroGradient Code:
type totalPressure;
p0 uniform 100000;
gamma 1.4;
rho rho;
psi none;
3)p:fixedValue T and U:zeroGradient Code:
type fixedValue;
value uniform 100000;
4)p:fixedValue T:fixedValue U:zeroGradient T: Code:
type fixedValue;
value uniform 288;
Code:
type fixedValue;
value uniform 100000;
why this simple phenomenon has these difficulties? could anyone give me any help? thanks. Last edited by immortality; January 25, 2013 at 06:34. |
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#2 |
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Senior Member
Ehsan
Join Date: Oct 2012
Location: Iran
Posts: 2,208
Rep Power: 28 ![]() |
any guidance or idea?just a small tube with higher pressure fluid than outside.what's wrong with the modelling?what BC is appropriate? can be linear schemes unstable?
Any thought is appreciated. |
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#3 |
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Senior Member
Ehsan
Join Date: Oct 2012
Location: Iran
Posts: 2,208
Rep Power: 28 ![]() |
fvSchemes:
Code:
fluxScheme Kurganov;
ddtSchemes
{
default Euler;
ddt(rho) Euler;
ddt(rhoU) Euler;
ddt(rhoE) Euler;
ddt(rho,U) Euler;
ddt(rho,e) Euler;
ddt(rho,omega) Euler;
ddt(rho,k) Euler;
}
gradSchemes
{
default none;
grad(U) Gauss linear;
grad(rho) Gauss linear;
grad(rhoU) Gauss linear;
grad((1|psi)) Gauss linear;
grad(e) Gauss linear;
grad(sqrt(((Cp|Cv)*(1|psi)))) Gauss linear;
// grad(c) Gauss linear;
grad(T) Gauss linear;
grad(omega) Gauss linear;
grad(k) Gauss linear;
}
divSchemes
{
default none;
div(tauMC) Gauss linear;
div(phi) Gauss linear;
div(phi,omega) Gauss linear;
div(phi,k) Gauss linear;
//div(phiEp) Gauss linaer;
//div(phiUp) Gauss linear;
//div(sigmaDotU) Gauss linear;
}
laplacianSchemes
{
default none;
laplacian(muEff,U) Gauss linear corrected;
laplacian(alphaEff,e) Gauss linear corrected;
laplacian(alpha,e) Gauss linear corrected;
laplacian(k,T) Gauss linear corrected;
laplacian(DepsilonEff,omega) Gauss linear corrected;
laplacian(DkEff,k) Gauss linear corrected;
laplacian(DomegaEff,omega) Gauss linear corrected;
}
interpolationSchemes
{
default none;
reconstruct(rho) vanLeer;
reconstruct(U) vanLeerV;
reconstruct(T) vanLeer;
interpolate(rho) linear;
interpolate(U) linear;
//interpolate(T) linear;
//interpolate(e) linear;
//interpolate(c) linear;
interpolate(rhoU) linear;
//interpolate(rPsi) linear;
interpolate(muEff) linear;
interpolate(tauMC) linear;
}
snGradSchemes
{
default none;
snGrad(U) corrected;
}
Code:
solvers
{
"(rho|rhoU|rhoE)"
{
solver diagonal;
}
U
{
solver smoothSolver;
smoother DICGaussSeidel;
nSweeps 4;
tolerance 1e-11;
relTol 0;
maxIter 2000;
}
h
{
$U;
tolerance 1e-12;
relTol 0;
maxIter 2000;
}
e
{
$U;
tolerance 1e-12;
relTol 0;
maxIter 5000;
}
"(k|omega)"
{
solver smoothSolver;
smoother GaussSeidel;
nSweeps 3;
tolerance 1e-11;
relTol 0;
maxIter 2000;
}
}
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#4 |
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Senior Member
Ehsan
Join Date: Oct 2012
Location: Iran
Posts: 2,208
Rep Power: 28 ![]() |
does someone know any experiment result of pressures at a scavenging process of a suddenly opened tube to surroundings?
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