[Kevin123]

Hello there,
I´m trying to run a 3D "intermixingFoam" simulation where 2 fluids are mixing in a rocket engine chamber, but it´s calculating the pressurefield in a weired way and has big continuity errors, I guess something is wrong with my boundry contidiones that I can´t figure out what. It would really help me out if someone has an idea what I´m doing wrong.
I´m attaching what my solver is telling me and the boudry conditiones to this post.(The website doesn´t support OpenFoams abstract files so they are in a zip file)

Cheers

[Martin_Sz]

I'd be glad to assist you with the pressure field and continuity errors you're encountering in your intermixingFoam simulation.
Understanding the Problem:
* Pressure Field Issues: The simulation is calculating the pressure field in an unexpected manner, suggesting potential errors in pressure boundary conditions or solution methods.
* Continuity Errors: Large continuity errors indicate inconsistencies in mass conservation, often linked to pressure-velocity coupling or boundary conditions.
Potential Causes:
* Incorrect Pressure Boundary Conditions: Double-check that pressure boundary conditions accurately reflect the physical scenario in your rocket engine chamber. Common issues include:
* Missing pressure boundary conditions.
* Inappropriate pressure values or types (e.g., specifying zeroGradient instead of a fixed value at outlets).
* Incompatibility with intermixingFoam: Ensure that your pressure boundary conditions are compatible with the intermixingFoam solver. Some solvers might have specific requirements for pressure specification.
Troubleshooting Steps:
* Review Pressure Boundary Conditions:
* Carefully examine your pressure boundary conditions for all patches in the domain.
* Verify that the types (fixedValue, outlet, etc.) and values are set correctly.
* Consult the intermixingFoam documentation for any specific requirements regarding pressure boundaries.
* Check for Common Errors:
* Ensure there are no no-slip wall conditions applied to patches where pressure is specified.
* If using a pressure outlet, make sure the reference pressure is set appropriately.
* Simplify and Isolate:
* If the issue persists, consider simplifying your case setup to isolate the problem.
* Start with a basic geometry and test with simpler boundary conditions to rule out geometric complexities.
* Examine Mesh Quality:
* While less likely, ensure your mesh has good quality, especially near walls and interfaces between fluids. Poor mesh quality can contribute to pressure and continuity errors.
* Consult Resources:
* Refer to the intermixingFoam documentation and tutorials for guidance on pressure boundary conditions in this specific solver.
* Search online forums or communities for similar issues and solutions related to intermixingFoam and pressure calculations.
Additional Tips:
* Provide more details about your pressure boundary conditions (types, values, patches) if you seek further assistance online.
* Consider sharing excerpts from your solver output (if possible) to get more specific troubleshooting advice.
By systematically addressing these potential causes, you should be able to resolve the pressure field issues and continuity errors in your intermixingFoam simulation.

[Kevin123]

Thanks Martin for your response,
Sorry for my late reply I didn´t had much time the last days.
I´ve tried your tips (to the extend of my skills). I used the GAMG algorithm due to its speed. It still have continuity error but since they are very small they don´t look like an issue to me. But now the program tries to divide by zero wich is a bigger issue.
I would guess that there is something wrong with my Pressurefield since I get the error while the program solves for p_rgh.
Also I´ve provided all my boudryfiles in a zip file since CFD Online doesn´t support these files and I felt the post would have been unnessarily long with the text in the post itself, or do you mean additional files like the fvSolution for example?
This is the last output I get with my current error.

PIMPLE: iteration 1
diagonal: Solving for alpha.air, Initial residual = 0, Final residual = 0, No Iterations 0
smoothSolver: Solving for alpha.other, Initial residual = 9.78753e-07, Final residual = 9.78753e-07, No Iterations 0
Air phase volume fraction = 0.999999 Min(alpha.air) = -6.789U5e-08 Max(alpha.air) = 1
Liquid phase volume fraction = 1.86708e-08 Min(alpha.other) = -1.85507e-05 Max(alpha.other) = 0.2148
diagonal: Solving for alpha.air, Initial residual = ®, Final residual = ®, No Iterations 0
smoothSolver: Solving for alpha.other, Initial residual = 9.78761e-07, Final residual = 9.78761e-07, No Iterations ©
Air phase volume fraction = 0.999999 Min(alpha.air) = -6.38835e-088 Max(alpha.air) = 1
Liquid phase volume fraction = 1.86708e-08 Min(alpha.other) = -1.85507e-05 Max(alpha.other) = 0.2148
GAMG: Solving for p_rgh, Initial residual = 0.0888073, Final residual = 0.00406167, No Iterations 2
GAMG Solving for p_rgh, Initial residual = 0.0510609, Final residual = 0.00507558, No Iterations 1
[stack trace]
#1 Foam::sigFpe::sigHandler(int) in /usr/lib/openfoam/openfoam2312/platforms/linux64GccDPInt320pt/Lib/LibOpenFOAM.so
#2 ? in /lib/x86_64-linux-gnu/libc.so.6
#3 Foan: :GAMGSolver: :scale(Foam: :Field<double>&, Foam::Field<double>&, Foam::lduMatrix const&, Foam::FieldField<Foam: :Field, double> const&, Foam: :UPtrList<Foan: :ldulnterfaceField const> const&, Foam: :Field<d
ouble> const&, unsigned char) const in /usr/lib/openfoam/openfoam2312/platforms/linux6U4GccDPInt320pt/lib/LibOpenFOAM.so
#4 Foam: :GAMGSolver: :Vcycle(Foan: :PtrList<Foam: :lduMatrix::smoother> const&, Foam: :Field<double>&, Foam::Field<double> const&, Foam: :Field<double>&, Foam::Field<double>&, Foam::Field<double>&, Foan: :Field<dou
ble>&, Foam: :Field<double>&, Foan: :PtrList<Foam: :Field<double> >&, Foam: :PtrList<Foam: :Field<double> >&, unsigned char) const in /usr/Lib/openfoam/openfoan2312/platforms/linux64GccDPInt320pt/Lib/LibOpenFOAM.so
#5 Foam: MGSolver: :solve(Foar 'ield<double>&, Foam::Field<double> const&, unsigned char) const in /usr/Lib/openfoam/openfoam2312/platforms/linux64GccDPInt320pt/lib/LibOpenFOAM.so
#6 Foam: :fvMatrix<double>: :solveSegregated(Foam: :dictionary const&) in /usr/Lib/openfoam/openfoam2312/platforms/linux6UGccDPInt320pt/lib/LibfiniteVolume.so
#7 ? in /usr/Lib/openfoam/openfoam2312/platforms/linux6llGccDPInt320pt/lib/libfiniteVolume.so
#8 Foam: :fvMesh::solve(Foan: :fvMatrix<double>&, Foam::dictionary const&) const in /usr/Lib/openfoam/openfoam2312/platforms/linux64GceDPInt320pt/lib/libfiniteVolume.so
#9 ? in /usr/Lib/openfoam/openfoam2312/platforms/linux64GccDPInt320pt/bin/interMixingFoam
#10 ? in /Lib/x86_64-linux-gnu/libc.so.6
_libe_start_main in /Lib/x86_64-Linux-gnu/libc.so.6
#12 ? in /usr/lib/openfoam/openfoam2312/platforms/linux64GccDPInt320pt/bin/interMixingFoam
Floating point exception
openfoam2312:-/OpenFOAM/root-v2312/run/Versuch5Intermixing-Kopiell/