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January 7, 2008, 10:44 
Usually rasinterfoam is faster

#1 
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Daniele Vicario
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Usually rasinterfoam is faster than lesinterfoam, isn't it ?
I'll give it a try. Can I keep the same solver/solution setup ?
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Daniele Vicario blueCFD2.1  Windows 7 

January 7, 2008, 14:23 
Even rasInterfoam is giving ba

#2 
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Daniele Vicario
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Even rasInterfoam is giving bad results.
I tried with and without turbolence and also changing the div gamma schemes to gamma01 1 but the result is sooner or later a picosec simulation. Apart from solver/solution/BC error could be some mesh problem. It's a tet mesh unvimported from Salome. Can a too coarse mesh cause this problems ? Checkmesh reports "only" 14 severe nonorth faces. Could a hex element mesh bring better results ? Thanks to anyone.
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Daniele Vicario blueCFD2.1  Windows 7 

January 8, 2008, 03:41 
I tried also reducing the inle

#3 
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Daniele Vicario
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I tried also reducing the inlet pressure from 1e5 to 1e4 an I've got the same results later in time.
It seems that changing BC from atmosphere to fixed pressure outlet things are going better (now in rasinterfoam without turbolence). I'm still running the simulation so I'll see. I would expect that atmosphere bc would be more appropriate, it's been used in the les tutorial for a similar case. Any hint ?
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Daniele Vicario blueCFD2.1  Windows 7 

January 8, 2008, 04:09 
You have messed up something e

#4 
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Hrvoje Jasak
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You have messed up something else, probably boundary conditions. First, set the discretisation to firstorder accuracy and see if the code runs. If it does not, you've got a clear problem (boundary conditions). When you fix it, you can then return to full LES setup.
The picosecond timestep you are seeing is the automatic timestep control trying to save you and failing. Switch it off (system/controlDict, and get the code to run  this will also show you where in the domain the failure occurs (you can dump the results every timestep and actually look at them). Enjoy, Hrv
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Hrvoje Jasak Providing commercial FOAM/OpenFOAM and CFD Consulting: http://wikki.co.uk 

January 8, 2008, 04:50 
Thanks Mr. Jasak,
Just to be

#5 
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Daniele Vicario
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Thanks Mr. Jasak,
Just to be sure. For firstorder accuracy you mean the following (for rasinterfoam): divSchemes { div(rho*phi,U) Gauss linear; div(phi,gamma) Gauss linear; div(phirb,gamma) Gauss linear; div(phi,k) Gauss linear; div(phi,epsilon) Gauss linear; div(phi,R) Gauss linear; div(R) Gauss linear; div(phi,nuTilda) Gauss linear; } Isn't it ? k and epsilon are disabked (turbolence off) at the moment. I don't know the use of R. I'll try.
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Daniele Vicario blueCFD2.1  Windows 7 

January 8, 2008, 06:23 
I tried with linear discretisa

#6 
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Daniele Vicario
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I tried with linear discretisation and fixed time step of 2us.
This is what i obtained: Courant Number mean: 4.00383e05 max: 4.14158 Time = 0.000628 MULES: Solving for gamma Liquid phase volume fraction = 0.0026595 Min(gamma) = 1.79162e36 Max(gamma) = 1 MULES: Solving for gamma Liquid phase volume fraction = 0.00265951 Min(gamma) = 6.05957e36 Max(gamma) = 1 MULES: Solving for gamma Liquid phase volume fraction = 0.00265952 Min(gamma) = 1.79162e36 Max(gamma) = 1 MULES: Solving for gamma Liquid phase volume fraction = 0.00265953 Min(gamma) = 4.27041e37 Max(gamma) = 1 #0 Foam::error::printStack(Foam:stream&) in "/home/caelinux/OpenFOAM/OpenFOAM1.4.1/lib/linuxGccDPOpt/libOpenFOAM.so" #1 Foam::sigFpe::sigFpeHandler(int) in "/home/caelinux/OpenFOAM/OpenFOAM1.4.1/lib/linuxGccDPOpt/libOpenFOAM.so" #2 Uninterpreted: [0xb7fd8420] #3 Foam::GaussSeidelSmoother::smooth(Foam::word const&, Foam::Field<double>&, Foam::lduMatrix const&, Foam::Field<double> const&, Foam::FieldField<foam::field,> const&, Foam::UPtrList<foam::lduinterfacefield> const&, unsigned char, int) in "/home/caelinux/OpenFOAM/OpenFOAM1.4.1/lib/linuxGccDPOpt/libOpenFOAM.so" #4 Foam::GaussSeidelSmoother::smooth(Foam::Field<doub le>&, Foam::Field<double> const&, unsigned char, int) const in "/home/caelinux/OpenFOAM/OpenFOAM1.4.1/lib/linuxGccDPOpt/libOpenFOAM.so" #5 Foam::smoothSolver::solve(Foam::Field<double>&, Foam::Field<double> const&, unsigned char) const in "/home/caelinux/OpenFOAM/OpenFOAM1.4.1/lib/linuxGccDPOpt/libOpenFOAM.so" #6 Foam::fvMatrix<foam::vector<double> >::solve(Foam::Istream&) in "/home/caelinux/OpenFOAM/OpenFOAM1.4.1/applications/bin/linuxGccDPOpt/rasInterF oam" #7 Foam::lduMatrix::solverPerformance Foam::solve<foam::vector<double> >(Foam::tmp<foam::fvmatrix<foam::vector<double> > > const&) in "/home/caelinux/OpenFOAM/OpenFOAM1.4.1/applications/bin/linuxGccDPOpt/rasInterF oam" #8 main in "/home/caelinux/OpenFOAM/OpenFOAM1.4.1/applications/bin/linuxGccDPOpt/rasInterF oam" #9 __libc_start_main in "/lib/i686/libc.so.6" #10 Foam::regIOobject::readIfModified() in "/home/caelinux/OpenFOAM/OpenFOAM1.4.1/applications/bin/linuxGccDPOpt/rasInterF oam" I check the very last step with Paraview but actually there's nothing strange (as far as I can understand: no value spike) The inlet velocity is fixed to 0.4m/s on the y axis, so after 0.6ms the water is almost still unmoved from the initial position. Just in case this are my BC gamma: internalField nonuniform List<scalar> //cut// boundaryField { inlet { type fixedValue; value uniform 1; } atmos { type zeroGradient; } wall { type zeroGradient; } } pd: internalField uniform 0; boundaryField { inlet { type zeroGradient; } atmos { type fixedValue; value uniform 0; } wall { type zeroGradient; } } U: internalField uniform (0 0 0); boundaryField { inlet { type fixedValue; value uniform (0 0.4 0); } atmos { type zeroGradient; } wall { type fixedValue; value uniform (0 0 0); } } nuTilda: internalField uniform 0; boundaryField { inlet { type fixedValue; value uniform 0; } atmos { type zeroGradient; } wall { type zeroGradient; } } If you have any idea I would appreciate, thanks
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Daniele Vicario blueCFD2.1  Windows 7 

January 8, 2008, 09:00 
I'm really very sorry to insis

#7 
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Daniele Vicario
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I'm really very sorry to insist but I'm stuck.
Even reducing the inlet velocity to approx (0,0,0) the solver stop after 6.7ms Co value seems right. This is the last step: Courant Number mean: 8.72853e06 max: 0.162675 deltaT = 9.5844e05 Time = 0.000557064 MULES: Solving for gamma Liquid phase volume fraction = 0.00264396 Min(gamma) = 1.13282e19 Max(gamma) = 1 MULES: Solving for gamma Liquid phase volume fraction = 0.00264396 Min(gamma) = 6.52214e20 Max(gamma) = 1 MULES: Solving for gamma Liquid phase volume fraction = 0.00264396 Min(gamma) = 6.41784e21 Max(gamma) = 1 MULES: Solving for gamma Liquid phase volume fraction = 0.00264396 Min(gamma) = 4.74896e21 Max(gamma) = 1 smoothSolver: Solving for Ux, Initial residual = 0.0769033, Final residual = 8.24476e07, No Iterations 4 smoothSolver: Solving for Uy, Initial residual = 0.0888143, Final residual = 9.62986e07, No Iterations 4 smoothSolver: Solving for Uz, Initial residual = 0.0913065, Final residual = 1.17177e07, No Iterations 5 GAMG: Solving for pd, Initial residual = 0.00890823, Final residual = 4.32939e07, No Iterations 6 GAMG: Solving for pd, Initial residual = 0.00226642, Final residual = 2.57883e07, No Iterations 5 GAMG: Solving for pd, Initial residual = 0.000503093, Final residual = 8.34177e07, No Iterations 3 GAMG: Solving for pd, Initial residual = 0.00045618, Final residual = 6.16192e07, No Iterations 5 GAMG: Solving for pd, Initial residual = 0.00016907, Final residual = 4.03424e07, No Iterations 3 GAMGPCG: Solving for pd, Initial residual = 3.91883e05, Final residual = 1.10265e09, No Iterations 3 time step continuity errors : sum local = 3.88878e14, global = 3.42051e16, cumulative = 1.47553e14 ExecutionTime = 242.19 s ClockTime = 243 s Courant Number mean: 1.22137e05 max: 0.217563 deltaT = 0.000115013 Time = 0.000672077 MULES: Solving for gamma Liquid phase volume fraction = 0.00264396 Min(gamma) = 7.54913e21 Max(gamma) = 1 MULES: Solving for gamma Liquid phase volume fraction = 0.00264396 Min(gamma) = 1.04923e20 Max(gamma) = 1 MULES: Solving for gamma Liquid phase volume fraction = 0.00264396 Min(gamma) = 5.72812e21 Max(gamma) = 1 MULES: Solving for gamma Liquid phase volume fraction = 0.00264396 Min(gamma) = 5.667e21 Max(gamma) = 1 #0 Foam::error::printStack(Foam:stream&) in "/home/caelinux/OpenFOAM/OpenFOAM1.4.1/lib/linuxGccDPOpt/libOpenFOAM.so" #1 Foam::sigFpe::sigFpeHandler(int) in "/home/caelinux/OpenFOAM/OpenFOAM1.4.1/lib/linuxGccDPOpt/libOpenFOAM.so" #2 Uninterpreted: [0xb7f3a420] #3 Foam::GaussSeidelSmoother::smooth(Foam::word const&, Foam::Field<double>&, Foam::lduMatrix const&, Foam::Field<double> const&, Foam::FieldField<foam::field,> const&, Foam::UPtrList<foam::lduinterfacefield> const&, unsigned char, int) in "/home/caelinux/OpenFOAM/OpenFOAM1.4.1/lib/linuxGccDPOpt/libOpenFOAM.so" #4 Foam::GaussSeidelSmoother::smooth(Foam::Field<doub le>&, Foam::Field<double> const&, unsigned char, int) const in "/home/caelinux/OpenFOAM/OpenFOAM1.4.1/lib/linuxGccDPOpt/libOpenFOAM.so" #5 Foam::smoothSolver::solve(Foam::Field<double>&, Foam::Field<double> const&, unsigned char) const in "/home/caelinux/OpenFOAM/OpenFOAM1.4.1/lib/linuxGccDPOpt/libOpenFOAM.so" #6 Foam::fvMatrix<foam::vector<double> >::solve(Foam::Istream&) in "/home/caelinux/OpenFOAM/OpenFOAM1.4.1/applications/bin/linuxGccDPOpt/rasInterF oam" #7 Foam::lduMatrix::solverPerformance Foam::solve<foam::vector<double> >(Foam::tmp<foam::fvmatrix<foam::vector<double> > > const&) in "/home/caelinux/OpenFOAM/OpenFOAM1.4.1/applications/bin/linuxGccDPOpt/rasInterF oam" #8 main in "/home/caelinux/OpenFOAM/OpenFOAM1.4.1/applications/bin/linuxGccDPOpt/rasInterF oam" #9 __libc_start_main in "/lib/i686/libc.so.6" #10 Foam::regIOobject::readIfModified() in "/home/caelinux/OpenFOAM/OpenFOAM1.4.1/applications/bin/linuxGccDPOpt/rasInterF oam" Thanks
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Daniele Vicario blueCFD2.1  Windows 7 

January 9, 2008, 05:05 
I tried to reduce the complexi

#8 
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Daniele Vicario
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I tried to reduce the complexity of the problem.
Now CheckMesh reports as follow: Create polyMesh for time = constant Time = constant Mesh stats points: 1743 edges: 9116 faces: 13509 internal faces: 11031 cells: 6135 boundary patches: 3 point zones: 0 face zones: 0 cell zones: 0 Number of cells of each type: hexahedra: 0 prisms: 0 wedges: 0 pyramids: 0 tet wedges: 0 tetrahedra: 6135 polyhedra: 0 Checking topology... Boundary definition OK. Point usage OK. Upper triangular ordering OK. Topological cell zipup check OK. Face vertices OK. Faceface connectivity OK. Number of regions: 1 (OK). Checking patch topology for multiply connected surfaces ... Patch Faces Points Surface fin 86 54 ok (not multiply connected) fout 102 62 ok (not multiply connected) wall 2290 1165 ok (not multiply connected) Checking geometry... Domain bounding box: (0.01275 0.0485 0.01275) (0.01275 0.06 0.01275) Boundary openness (2.01305e17 1.76262e17 5.19899e17) OK. Max cell openness = 1.30668e16 OK. Max aspect ratio = 6.73238 OK. Minumum face area = 6.85693e08. Maximum face area = 4.25408e05. Face area magnitudes OK. Min volume = 1.05176e11. Max volume = 8.75739e08. Total volume = 3.24662e05. Cell volumes OK. Mesh nonorthogonality Max: 62.5586 average: 21.1981 Nonorthogonality check OK. Face pyramids OK. Max skewness = 0.979387 OK. Min/max edge length = 0.000327004 0.0117359 OK. All angles in faces OK. All face flatness OK. Mesh OK. The geometry consists of just some pipes with different diameters. One fixed velocity inlet. One fixed pressure outlet. Wall Solver: rasinterfoam Scheme: all linear Solvers: as tutorial rasinterfoam (mainly PBiCG, for pd uses PCG) The inlet patch and a piece of the inlet pipe are gamma1 filled. After some iteration in which i can see (paraview) the liquid pushing the air phase into the outlet pipe it seems that something is happening at the liquid surface. Strange pressure spikes. What am I missing ? I changed the mesh,the solver,the scheme and the solution. It has to be related to BC then... Thanks.
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Daniele Vicario blueCFD2.1  Windows 7 

January 10, 2008, 05:30 
I also tried to exclude surfac

#9 
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Daniele Vicario
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I also tried to exclude surface tension and interface compression so I set sigma=0 and cgamma=0.
Note: I use a coarser mesh in order to have faster results. Check mesh reports as follow: Create polyMesh for time = constant Time = constant Mesh stats points: 2581 edges: 14500 faces: 22343 internal faces: 19349 cells: 10423 boundary patches: 3 point zones: 0 face zones: 0 cell zones: 0 Number of cells of each type: hexahedra: 0 prisms: 0 wedges: 0 pyramids: 0 tet wedges: 0 tetrahedra: 10423 polyhedra: 0 Checking topology... Boundary definition OK. Point usage OK. Upper triangular ordering OK. Topological cell zipup check OK. Face vertices OK. Faceface connectivity OK. Number of regions: 1 (OK). Checking patch topology for multiply connected surfaces ... Patch Faces Points Surface fin 43 31 ok (not multiply connected) fout 44 32 ok (not multiply connected) wall 2907 1471 ok (not multiply connected) Checking geometry... Domain bounding box: (0.01275 0.0485 0.0127498) (0.01275 0.06 0.0127496) Boundary openness (4.75469e18 4.09572e17 3.83941e17) OK. Max cell openness = 1.3167e16 OK. Max aspect ratio = 4.22384 OK. Minumum face area = 2.19126e07. Maximum face area = 2.99902e05. Face area magnitudes OK. Min volume = 4.8208e11. Max volume = 5.25136e08. Total volume = 3.24903e05. Cell volumes OK. Mesh nonorthogonality Max: 47.8867 average: 16.8891 Nonorthogonality check OK. Face pyramids OK. Max skewness = 0.679106 OK. Min/max edge length = 0.000657036 0.00919595 OK. All angles in faces OK. All face flatness OK. Mesh OK. With automatic time step adjust limiting Co to 0.4 here is what I obtain. Better then before but after 21ms Co starts to increase so time step reaches ps ! Has anyone an idea of what is happening ? I really hope to have done a very stupid error, otherwise I'm a "little bit" worried of so problematic fine tuning of OF.
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Daniele Vicario blueCFD2.1  Windows 7 

January 10, 2008, 06:12 
Sorry, I wanted to include som

#10 
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Daniele Vicario
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Sorry, I wanted to include some movies but they're too big.
These are the pictures of the latest time step. U values seems correct. I've got an inlet 21mm diam. cylinder at 0.4m/sec and an outlet of 5mm diam.
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Daniele Vicario blueCFD2.1  Windows 7 

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