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suitable boundary condition for scavenging process? |
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January 24, 2013, 17:38 |
suitable boundary condition for scavenging process?
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#1 |
Senior Member
Ehsan
Join Date: Oct 2012
Location: Iran
Posts: 2,208
Rep Power: 27 |
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 05:34. |
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January 25, 2013, 01:11 |
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#2 |
Senior Member
Ehsan
Join Date: Oct 2012
Location: Iran
Posts: 2,208
Rep Power: 27 |
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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January 25, 2013, 06:48 |
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#3 |
Senior Member
Ehsan
Join Date: Oct 2012
Location: Iran
Posts: 2,208
Rep Power: 27 |
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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January 25, 2013, 19:10 |
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#4 |
Senior Member
Ehsan
Join Date: Oct 2012
Location: Iran
Posts: 2,208
Rep Power: 27 |
does someone know any experiment result of pressures at a scavenging process of a suddenly opened tube to surroundings?
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