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Old   May 2, 2011, 04:34
Default AlphaContactAngle boundary condition
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Andrea Ferrari
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Hi All,

i have some questions regarding the AlphaContactAngle boundary condition.
1)What are the correct bundary conditions for the pressure (p_rgh) if a use limit none in the alpha1 file? Using fixedFluxPressure (like the limit Gradient case) i got good results for theta0=40 but very strange results with theta0=10, the maximum values ​​of alpha become enormous. here le log file:

MULES: Solving for alpha1
Liquid phase volume fraction = 0.636986 Min(alpha1) = -2.9577e-26 Max(alpha1) = 3.81992e+11
MULES: Solving for alpha1Liquid phase volume fraction = 0.637439 Min(alpha1) = -2.67682e-26 Max(alpha1) = 3.81992e+11

DICPCG: Solving for p_rgh, Initial residual = 0.0375572, Final residual = 0.000557129, No Iterations 1
time step continuity errors : sum local = 1.93235e-07, global = 7.18295e-13, cumulative = 1.2344e-08
DICPCG: Solving for p_rgh, Initial residual = 0.00055013, Final residual = 2.22344e-05, No Iterations 5
time step continuity errors : sum local = 7.77818e-09, global = 6.9869e-13, cumulative = 1.23447e-08
DICPCG: Solving for p_rgh, Initial residual = 2.26382e-05, Final residual = 8.12487e-08, No Iterations 114
time step continuity errors : sum local = 2.85235e-11, global = -2.53878e-13, cumulative = 1.23445e-08
ExecutionTime = 25.49 s ClockTime = 25 s

Courant Number mean: 0.000124307 max: 0.01075
Interface Courant Number mean: 2.48437e-05 max: 0.00766732
deltaT = 4.07509e-05
Time = 0.0158494

MULES: Solving for alpha1
#0 Foam::error:rintStack(Foam::Ostream&) in "/opt/OpenFOAM/OpenFOAM-1.7.1/lib/linux64GccDPOpt/libOpenFOAM.so"
#1 Foam::sigFpe::sigFpeHandler(int) in "/opt/OpenFOAM/OpenFOAM-1.7.1/lib/linux64GccDPOpt/libOpenFOAM.so"
#2 ?? in "/lib64/libc.so.6"
#3 void Foam::MULES::limiter<Foam::geometricOneField, Foam::zeroField, Foam::zeroField>(Foam::Field<double>&, Foam::geometricOneField const&, Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh> const&, Foam::GeometricField<double, Foam::fvsPatchField, Foam::surfaceMesh> const&, Foam::GeometricField<double, Foam::fvsPatchField, Foam::surfaceMesh> const&, Foam::zeroField const&, Foam::zeroField const&, double, double, int) in "/opt/OpenFOAM/OpenFOAM-1.7.1/lib/linux64GccDPOpt/libfiniteVolume.so"
#4 void Foam::MULES::explicitSolve<Foam::geometricOneField , Foam::zeroField, Foam::zeroField>(Foam::geometricOneField const&, Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh>&, Foam::GeometricField<double, Foam::fvsPatchField, Foam::surfaceMesh> const&, Foam::GeometricField<double, Foam::fvsPatchField, Foam::surfaceMesh>&, Foam::zeroField const&, Foam::zeroField const&, double, double) in "/opt/OpenFOAM/OpenFOAM-1.7.1/lib/linux64GccDPOpt/libfiniteVolume.so"
#5 Foam::MULES::explicitSolve(Foam::GeometricField<do uble, Foam::fvPatchField, Foam::volMesh>&, Foam::GeometricField<double, Foam::fvsPatchField, Foam::surfaceMesh> const&, Foam::GeometricField<double, Foam::fvsPatchField, Foam::surfaceMesh>&, double, double) in "/opt/OpenFOAM/OpenFOAM-1.7.1/lib/linux64GccDPOpt/libfiniteVolume.so"
#6 main in "/opt/OpenFOAM/OpenFOAM-1.7.1/applications/bin/linux64GccDPOpt/interFoam"
#7 __libc_start_main in "/lib64/libc.so.6"
#8 Foam::regIOobject::writeObject(Foam::IOstream::str eamFormat, Foam::IOstream::versionNumber, Foam::IOstream::compressionType) const in "/opt/OpenFOAM/OpenFOAM-1.7.1/applications/bin/linux64GccDPOpt/interFoam"


Using limit Alpha (with fixedFluxPressure in the p_rgh file) the simulations seems ok but i would like to know if i'm doing something wrong in the boundary condition definition in the case of No limit on the contact angle.

2)The second question is related to the condition on the normal vector to the the interface, coming from the contact angle. Is the condition always applied on a wall boundary, also in the bulk phase where alpha=0 or alpha=1?. This does not make a wrong curvature (divergence of the normal vector, that is fixed on a wall boundary using the contact angle patch) on the walls where there is no interface? Runnig simulations in simple capillary tube basically I got, in the first cell close to the wall, two "lines" of curvature> 0, but it should be zero at these points except where there is the interface.
Hope it 's clear!


Thanks in advance for any help!

Andrea
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