sharonyue 
December 1, 2012 04:01 
same geometry,structured and unstructured mesh,different behaviour.
1 Attachment(s)
Hi Foamers:
I use the same geometry but different mesh which one is structured and the other is unstructured simulating bubblecolumn via twoPhaseEulerFoam, the other things such as BCs,FVscheme is totally the same.
while running, the deltaT is getting smaller and smaller in unstructured mesh,but delta T is stable in structured mesh. I check the unstructured mesh is OK, and the quality is above 0.36.
can anybody explain this to me? thanks in advance.
Code:
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
Create time
Create mesh for time = 0
Reading g
Reading transportProperties
Calculating face flux field phi1
Calculating face flux field phi2
Reading field alpha1
Reading field p
Reading field k
Reading field epsilon
Calculating field nut2
Calculating field nuEff1
Calculating field nuEff2
Calculating field DDtU1 and DDtU2
Calculating field g.h
Selecting dragModel for phase 1: SchillerNaumann
Selecting dragModel for phase 2: SchillerNaumann
dragPhase is 1
Selecting viscosityModel Syamlal
Selecting conductivityModel HrenyaSinclair
Selecting radialModel SinclairJackson
Selecting granularPressureModel Lun
Selecting frictionalStressModel JohnsonJackson
Courant Number mean: 1.38889e06 max: 0.0114746
PIMPLE: Operating solver in PISO mode
Starting time loop
Courant Number mean: 1.37514e06 max: 0.011361
Max Ur Courant Number = 0.011361
deltaT = 0.00235294
Time = 0.00235294
MULES: Solving for alpha1
MULES: Solving for alpha1
Dispersed phase volume fraction = 0.400913 Min(alpha1) = 0 Max(alpha1) = 1
GAMG: Solving for p, Initial residual = 1, Final residual = 0.0863091, No Iterations 4
time step continuity errors : sum local = 1.06044e05, global = 1.14961e06, cumulative = 1.14961e06
GAMG: Solving for p, Initial residual = 0.000385431, Final residual = 4.25161e09, No Iterations 8
time step continuity errors : sum local = 2.34062e08, global = 8.86366e09, cumulative = 1.15847e06
ExecutionTime = 1.83 s ClockTime = 2 s
Courant Number mean: 0.000961133 max: 0.281556
Max Ur Courant Number = 0.284771
deltaT = 0.0027451
Time = 0.00509804
MULES: Solving for alpha1
MULES: Solving for alpha1
Dispersed phase volume fraction = 0.400913 Min(alpha1) = 1.12164e20 Max(alpha1) = 1
GAMG: Solving for p, Initial residual = 8.63083e05, Final residual = 4.00274e06, No Iterations 1
time step continuity errors : sum local = 2.73396e05, global = 2.22315e06, cumulative = 1.06468e06
GAMG: Solving for p, Initial residual = 4.42412e05, Final residual = 5.60681e09, No Iterations 7
time step continuity errors : sum local = 4.22789e08, global = 6.16051e10, cumulative = 1.06529e06
ExecutionTime = 3.15 s ClockTime = 3 s
Courant Number mean: 0.0017551 max: 0.699786
Max Ur Courant Number = 0.556128
deltaT = 0.00194902
Time = 0.00704706
MULES: Solving for alpha1
MULES: Solving for alpha1
Dispersed phase volume fraction = 0.400913 Min(alpha1) = 6.81353e17 Max(alpha1) = 1
GAMG: Solving for p, Initial residual = 3.65894e05, Final residual = 1.57627e06, No Iterations 1
time step continuity errors : sum local = 5.16964e06, global = 9.58478e08, cumulative = 9.69446e07
GAMG: Solving for p, Initial residual = 5.6711e05, Final residual = 6.50899e09, No Iterations 6
time step continuity errors : sum local = 2.37495e08, global = 3.80727e09, cumulative = 9.65639e07
ExecutionTime = 4.44 s ClockTime = 5 s
Courant Number mean: 0.00167936 max: 1.02324
Max Ur Courant Number = 0.747501
deltaT = 1.99755e06
Time = 0.00949938
MULES: Solving for alpha1
MULES: Solving for alpha1
Dispersed phase volume fraction = 0.400913 Min(alpha1) = 8.90338e22 Max(alpha1) = 1
GAMG: Solving for p, Initial residual = 0.0481777, Final residual = 0.00240455, No Iterations 1
time step continuity errors : sum local = 7.55737e07, global = 8.0092e10, cumulative = 8.87419e07
GAMG: Solving for p, Initial residual = 0.170165, Final residual = 5.99529e09, No Iterations 14
time step continuity errors : sum local = 2.58254e12, global = 1.71226e13, cumulative = 8.87418e07
ExecutionTime = 25.1 s ClockTime = 25 s
Courant Number mean: 0.000246545 max: 0.954781
Max Ur Courant Number = 0.715363
deltaT = 1.04607e06
Time = 0.00950043
MULES: Solving for alpha1
MULES: Solving for alpha1
Dispersed phase volume fraction = 0.400913 Min(alpha1) = 8.90337e22 Max(alpha1) = 1
GAMG: Solving for p, Initial residual = 0.0453175, Final residual = 0.00277426, No Iterations 1
time step continuity errors : sum local = 8.16799e07, global = 3.74529e10, cumulative = 8.87044e07
GAMG: Solving for p, Initial residual = 0.112757, Final residual = 4.36559e09, No Iterations 14
time step continuity errors : sum local = 1.57546e12, global = 1.38487e13, cumulative = 8.87044e07
ExecutionTime = 26.55 s ClockTime = 27 s
Courant Number mean: 0.000191191 max: 0.775023
Max Ur Courant Number = 0.526832
deltaT = 6.74865e07
Time = 0.0095011
MULES: Solving for alpha1
MULES: Solving for alpha1
Dispersed phase volume fraction = 0.400913 Min(alpha1) = 8.90337e22 Max(alpha1) = 1
GAMG: Solving for p, Initial residual = 0.0344062, Final residual = 0.00217738, No Iterations 1
time step continuity errors : sum local = 7.2002e07, global = 5.49242e10, cumulative = 8.86494e07
GAMG: Solving for p, Initial residual = 0.0678397, Final residual = 7.71205e09, No Iterations 13
time step continuity errors : sum local = 2.89794e12, global = 2.90138e13, cumulative = 8.86494e07
ExecutionTime = 28.17 s ClockTime = 28 s
Courant Number mean: 0.000169 max: 0.691341
Max Ur Courant Number = 0.421516
deltaT = 4.88083e07
Time = 0.00950159
MULES: Solving for alpha1
MULES: Solving for alpha1
Dispersed phase volume fraction = 0.400913 Min(alpha1) = 8.90337e22 Max(alpha1) = 1
GAMG: Solving for p, Initial residual = 0.0242849, Final residual = 0.00133999, No Iterations 1
time step continuity errors : sum local = 5.12642e07, global = 7.3266e10, cumulative = 8.85762e07
GAMG: Solving for p, Initial residual = 0.0466661, Final residual = 6.45613e09, No Iterations 13
time step continuity errors : sum local = 2.72667e12, global = 2.42677e13, cumulative = 8.85761e07
ExecutionTime = 29.69 s ClockTime = 30 s
Courant Number mean: 0.00016667 max: 0.681466
Max Ur Courant Number = 0.389559
deltaT = 3.58113e07
Time = 0.00950195
MULES: Solving for alpha1
MULES: Solving for alpha1
Dispersed phase volume fraction = 0.400913 Min(alpha1) = 8.90337e22 Max(alpha1) = 1
GAMG: Solving for p, Initial residual = 0.0275894, Final residual = 0.00152494, No Iterations 1
time step continuity errors : sum local = 6.50407e07, global = 7.86185e10, cumulative = 8.84975e07
GAMG: Solving for p, Initial residual = 0.048091, Final residual = 7.15538e09, No Iterations 13
time step continuity errors : sum local = 3.39665e12, global = 3.10169e13, cumulative = 8.84975e07
ExecutionTime = 31.21 s ClockTime = 32 s
Courant Number mean: 0.000177114 max: 0.742118
Max Ur Courant Number = 0.434414
deltaT = 2.41277e07
Time = 0.00950219
MULES: Solving for alpha1
MULES: Solving for alpha1
Dispersed phase volume fraction = 0.400913 Min(alpha1) = 8.90336e22 Max(alpha1) = 1
GAMG: Solving for p, Initial residual = 0.0434491, Final residual = 0.00265364, No Iterations 1
time step continuity errors : sum local = 1.17267e06, global = 7.89578e10, cumulative = 8.84185e07
GAMG: Solving for p, Initial residual = 0.0916966, Final residual = 4.20824e09, No Iterations 14
time step continuity errors : sum local = 2.22575e12, global = 2.16475e13, cumulative = 8.84185e07
ExecutionTime = 32.73 s ClockTime = 33 s
Courant Number mean: 0.000201607 max: 0.927977
Max Ur Courant Number = 0.614956
deltaT = 1.30002e07
Time = 0.00950232
MULES: Solving for alpha1
MULES: Solving for alpha1
Dispersed phase volume fraction = 0.400913 Min(alpha1) = 8.90336e22 Max(alpha1) = 1
GAMG: Solving for p, Initial residual = 0.0523101, Final residual = 0.00307465, No Iterations 1
time step continuity errors : sum local = 1.1458e06, global = 7.83281e10, cumulative = 8.83402e07
GAMG: Solving for p, Initial residual = 0.167959, Final residual = 6.72381e09, No Iterations 14
time step continuity errors : sum local = 3.37666e12, global = 1.97947e13, cumulative = 8.83402e07
ExecutionTime = 34.2 s ClockTime = 34 s
Courant Number mean: 0.000213776 max: 1.09291
Max Ur Courant Number = 0.801885
deltaT = 5.94748e08
Time = 0.00950238
MULES: Solving for alpha1
MULES: Solving for alpha1
Dispersed phase volume fraction = 0.400913 Min(alpha1) = 8.90336e22 Max(alpha1) = 1
GAMG: Solving for p, Initial residual = 0.0529512, Final residual = 0.00271119, No Iterations 1
time step continuity errors : sum local = 7.97202e07, global = 7.88211e10, cumulative = 8.82613e07
GAMG: Solving for p, Initial residual = 0.213293, Final residual = 8.38933e09, No Iterations 14
time step continuity errors : sum local = 3.56226e12, global = 1.41309e13, cumulative = 8.82613e07
ExecutionTime = 35.67 s ClockTime = 36 s
Courant Number mean: 0.000203657 max: 1.09677
Max Ur Courant Number = 0.834422
deltaT = 2.71137e08
Time = 0.0095024
MULES: Solving for alpha1
MULES: Solving for alpha1
Dispersed phase volume fraction = 0.400913 Min(alpha1) = 8.90336e22 Max(alpha1) = 1
GAMG: Solving for p, Initial residual = 0.0456457, Final residual = 0.00239763, No Iterations 1
time step continuity errors : sum local = 6.07151e07, global = 6.76636e10, cumulative = 8.81937e07
GAMG: Solving for p, Initial residual = 0.170025, Final residual = 7.23531e09, No Iterations 14
time step continuity errors : sum local = 2.45147e12, global = 1.08e13, cumulative = 8.81936e07
ExecutionTime = 37.23 s ClockTime = 38 s
Courant Number mean: 0.000167332 max: 0.906812
Max Ur Courant Number = 0.660191
deltaT = 1.495e08
Time = 0.00950242
MULES: Solving for alpha1
MULES: Solving for alpha1
Dispersed phase volume fraction = 0.400913 Min(alpha1) = 8.90336e22 Max(alpha1) = 1
GAMG: Solving for p, Initial residual = 0.0400672, Final residual = 0.00243865, No Iterations 1
time step continuity errors : sum local = 6.57129e07, global = 5.7262e10, cumulative = 8.81364e07
GAMG: Solving for p, Initial residual = 0.109301, Final residual = 4.88328e09, No Iterations 14
time step continuity errors : sum local = 1.58805e12, global = 1.09765e13, cumulative = 8.81364e07
ExecutionTime = 38.74 s ClockTime = 39 s
Courant Number mean: 0.000143578 max: 0.769801
Max Ur Courant Number = 0.514251
deltaT = 9.7103e09
Time = 0.00950243
> FOAM Warning :
From function Time::operator++()
in file db/Time/Time.C at line 1024
Increased the timePrecision from 6 to 7 to distinguish between timeNames at time 0.00950242
MULES: Solving for alpha1
MULES: Solving for alpha1
Dispersed phase volume fraction = 0.400913 Min(alpha1) = 8.90336e22 Max(alpha1) = 1
GAMG: Solving for p, Initial residual = 0.0301994, Final residual = 0.00188676, No Iterations 1
time step continuity errors : sum local = 5.87628e07, global = 4.48811e10, cumulative = 8.80915e07
GAMG: Solving for p, Initial residual = 0.0676315, Final residual = 8.08041e09, No Iterations 13
time step continuity errors : sum local = 2.84689e12, global = 3.41917e13, cumulative = 8.80915e07
ExecutionTime = 40.17 s ClockTime = 40 s
Courant Number mean: 0.000133312 max: 0.69952
Max Ur Courant Number = 0.425703
deltaT = 6.94069e09
Time = 0.009502436
