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-   -   About sigmaExp of solidEquilibriumDisplacementFoam OpenFOAM 14 (https://www.cfd-online.com/Forums/openfoam-solving/59684-about-sigmaexp-solidequilibriumdisplacementfoam-openfoam-14-a.html)

jerrywei May 24, 2007 22:04

In solidEquilibriumDisplacemen
 
In solidEquilibriumDisplacementFoam,there are two Sigma tensor:

sigmaExp = (lambda - mu)*gradDcorr + mu*gradDcorr.T()
+ (lambda*I)*tr(gradDcorr);

sigmaD += accFac*(mu*twoSymm(gradDcorr)
+ (lambda*I)*tr(gradDcorr));

and solve equation with sigmaD and sigmaExp:
solve
(
fvm::laplacian(2*mu + lambda, Dcorr, "laplacian(DD,Dcorr)")
+ fvc::div(sigmaExp + sigmaD)
);



But in StressedFoam(OpenFOAM 1.3):

fvVectorMatrix UEqn
(
fvm::d2dt2(U)
==
fvm::laplacian(2*mu + lambda, U, "laplacian(DU,U)")

+ fvc::div
(
mu*gradU.T() + lambda*(I*tr(gradU)) - (mu + lambda)*gradU,
"div(sigma)"
)
);

I can't understand about that the coefficient is not the same between sigmaExp and stressedFOAM:

sigmaExp: (lambda - mu)*gradDcorr

stressedFOAM: - (mu + lambda)*gradU

and is there reference paper about the new solver of solidEquilibriumDisplacementFoam?(The method is cool and good)

thank you very much!!!
Jerry

gascortado September 15, 2011 13:16

I have question related to StressedFoam. The equation to be solved appears to be the one described here (equation #6) : http://powerlab.fsb.hr/ped/kturbo/Op...tressPaper.pdf

However, the solver solves this equation :

fvVectorMatrix UsolidEqn
(
fvm::d2dt2(Usolid)
==
fvm::laplacian(2*mu + lambda, Usolid, "laplacian(DU,U)")
+ fvc::div
(
mu*gradUsolid.T() + lambda*(I*tr(gradUsolid)) - (mu + lambda)*gradUsolid,
"div(sigma)"
)
);


I dont understand where the (mu + lambda)*gradUsolid and fvm::laplacian(2*mu + lambda, Usolid, "laplacian(DU,U)") terms is coming from


Any idea?? I'll appreciate any help. THanks


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