[zhouhoucun]

Hello everyone,
I meet a problem when I use the interPhaseChangeFoam to solve cavitation. The liquid volume fraction sometimes is negative, why this happend and how to correct it.
Thank you!

Some part of the log file reads below:


Time = 0.0056369

DILUPBiCG: Solving for alpha1, Initial residual = 1.98079e-08, Final residual = 2.35875e-13, No Iterations 1
Liquid phase volume fraction = 0.999986 Min(alpha1) = 3.67397e-08 Max(alpha1) = 1
GAMG: Solving for p_rgh, Initial residual = 2.28663e-07, Final residual = 8.71765e-10, No Iterations 1
GAMG: Solving for p_rgh, Initial residual = 1.88297e-08, Final residual = 6.29201e-10, No Iterations 1
time step continuity errors : sum local = 2.18658e-08, global = 5.46088e-10, cumulative = -7.63934e-05
GAMG: Solving for p_rgh, Initial residual = 7.47701e-08, Final residual = 4.65551e-10, No Iterations 1
GAMGPCG: Solving for p_rgh, Initial residual = 1.00922e-08, Final residual = 1.00922e-08, No Iterations 0
time step continuity errors : sum local = 2.18706e-08, global = 5.46088e-10, cumulative = -7.63929e-05
ExecutionTime = 80989.1 s ClockTime = 81112 s

Courant Number mean: 0.00309833 max: 0.585979

Time = 0.0056374

DILUPBiCG: Solving for alpha1, Initial residual = 1.98261e-08, Final residual = 2.36535e-13, No Iterations 1
Liquid phase volume fraction = 0.999986 Min(alpha1) = -7.74337e-09 Max(alpha1) = 1
GAMG: Solving for p_rgh, Initial residual = 2.47487e-07, Final residual = 8.93709e-10, No Iterations 1
GAMG: Solving for p_rgh, Initial residual = 1.88038e-08, Final residual = 6.25815e-10, No Iterations 1
time step continuity errors : sum local = 2.18726e-08, global = 5.46324e-10, cumulative = -7.63923e-05
GAMG: Solving for p_rgh, Initial residual = 7.61096e-08, Final residual = 4.40814e-10, No Iterations 1
GAMGPCG: Solving for p_rgh, Initial residual = 9.04325e-09, Final residual = 9.04325e-09, No Iterations 0
time step continuity errors : sum local = 2.18767e-08, global = 5.46324e-10, cumulative = -7.63918e-05
ExecutionTime = 80990.9 s ClockTime = 81113 s

Courant Number mean: 0.00309833 max: 0.585899

Time = 0.0056379

DILUPBiCG: Solving for alpha1, Initial residual = 1.98583e-08, Final residual = 2.37556e-13, No Iterations 1
Liquid phase volume fraction = 0.999986 Min(alpha1) = 4.10681e-08 Max(alpha1) = 1
GAMG: Solving for p_rgh, Initial residual = 2.46697e-07, Final residual = 8.71039e-10, No Iterations 1
GAMG: Solving for p_rgh, Initial residual = 1.89244e-08, Final residual = 6.30179e-10, No Iterations 1
time step continuity errors : sum local = 2.18737e-08, global = 5.46559e-10, cumulative = -7.63912e-05
GAMG: Solving for p_rgh, Initial residual = 7.57724e-08, Final residual = 4.73074e-10, No Iterations 1
GAMGPCG: Solving for p_rgh, Initial residual = 1.02177e-08, Final residual = 1.02177e-08, No Iterations 0
time step continuity errors : sum local = 2.18785e-08, global = 5.4656e-10, cumulative = -7.63907e-05
ExecutionTime = 80992.6 s ClockTime = 81115 s

[Tushar@cfd]

Originally Posted by zhouhoucun

Hello everyone,
I meet a problem when I use the interPhaseChangeFoam to solve cavitation. The liquid volume fraction sometimes is negative, why this happend and how to correct it.
Thank you!

Some part of the log file reads below:


Time = 0.0056369

DILUPBiCG: Solving for alpha1, Initial residual = 1.98079e-08, Final residual = 2.35875e-13, No Iterations 1
Liquid phase volume fraction = 0.999986 Min(alpha1) = 3.67397e-08 Max(alpha1) = 1
GAMG: Solving for p_rgh, Initial residual = 2.28663e-07, Final residual = 8.71765e-10, No Iterations 1
GAMG: Solving for p_rgh, Initial residual = 1.88297e-08, Final residual = 6.29201e-10, No Iterations 1
time step continuity errors : sum local = 2.18658e-08, global = 5.46088e-10, cumulative = -7.63934e-05
GAMG: Solving for p_rgh, Initial residual = 7.47701e-08, Final residual = 4.65551e-10, No Iterations 1
GAMGPCG: Solving for p_rgh, Initial residual = 1.00922e-08, Final residual = 1.00922e-08, No Iterations 0
time step continuity errors : sum local = 2.18706e-08, global = 5.46088e-10, cumulative = -7.63929e-05
ExecutionTime = 80989.1 s ClockTime = 81112 s

Courant Number mean: 0.00309833 max: 0.585979

Time = 0.0056374

DILUPBiCG: Solving for alpha1, Initial residual = 1.98261e-08, Final residual = 2.36535e-13, No Iterations 1
Liquid phase volume fraction = 0.999986 Min(alpha1) = -7.74337e-09 Max(alpha1) = 1
GAMG: Solving for p_rgh, Initial residual = 2.47487e-07, Final residual = 8.93709e-10, No Iterations 1
GAMG: Solving for p_rgh, Initial residual = 1.88038e-08, Final residual = 6.25815e-10, No Iterations 1
time step continuity errors : sum local = 2.18726e-08, global = 5.46324e-10, cumulative = -7.63923e-05
GAMG: Solving for p_rgh, Initial residual = 7.61096e-08, Final residual = 4.40814e-10, No Iterations 1
GAMGPCG: Solving for p_rgh, Initial residual = 9.04325e-09, Final residual = 9.04325e-09, No Iterations 0
time step continuity errors : sum local = 2.18767e-08, global = 5.46324e-10, cumulative = -7.63918e-05
ExecutionTime = 80990.9 s ClockTime = 81113 s

Courant Number mean: 0.00309833 max: 0.585899

Time = 0.0056379

DILUPBiCG: Solving for alpha1, Initial residual = 1.98583e-08, Final residual = 2.37556e-13, No Iterations 1
Liquid phase volume fraction = 0.999986 Min(alpha1) = 4.10681e-08 Max(alpha1) = 1
GAMG: Solving for p_rgh, Initial residual = 2.46697e-07, Final residual = 8.71039e-10, No Iterations 1
GAMG: Solving for p_rgh, Initial residual = 1.89244e-08, Final residual = 6.30179e-10, No Iterations 1
time step continuity errors : sum local = 2.18737e-08, global = 5.46559e-10, cumulative = -7.63912e-05
GAMG: Solving for p_rgh, Initial residual = 7.57724e-08, Final residual = 4.73074e-10, No Iterations 1
GAMGPCG: Solving for p_rgh, Initial residual = 1.02177e-08, Final residual = 1.02177e-08, No Iterations 0
time step continuity errors : sum local = 2.18785e-08, global = 5.4656e-10, cumulative = -7.63907e-05
ExecutionTime = 80992.6 s ClockTime = 81115 s

Dear zhouhoucun,

There could be many minor reasons related to CFD. But the major reason could be negative volumes: Check your mesh for the negative volumes, try removing it.

-
Best Luck!

[zhouhoucun]

Originally Posted by Tushar@cfd

Dear zhouhoucun,

There could be many minor reasons related to CFD. But the major reason could be negative volumes: Check your mesh for the negative volumes, try removing it.

-
Best Luck!

Dear Tushar,
Thank you very much to reply my question, I will check the mesh carefully and try again.

Yours,
Zhou