leizhao512 
September 10, 2015 13:07 
icoFoam diverges when simpleFoam converges
3 Attachment(s)
Hi, I am trying to simulate a laminar flow through a tube. Because it has complex geometry , I meshed it through ICEM and here iis the picture. https://drive.google.com/file/d/0BzN...ew?usp=sharing
The minimum mesh quality is 0.3 in ICEM and I also used checkMesh in openFoam, which said everything is OK.
Initially I used Fluent to simulate the flow on both steady state and transient state and I proved that the flow is steady. (the time step I used in Fluent is 10s)Then I used icoFoam to simulate this case, however, it got divergent quickly in the first 100 time steps. Then I tried simpleFoam to simulate it as steady state and it converged. What I did next is that I used the steady state solution ofsimpleFoam as the initial condition of icoFoam, and keep the same schemes and linear solvers. However, icoFoam got divergent real fast, even if I shrink the time step to 0.1s.
Can anybody help me with this? Thank you.
Quote:
Time = 3003
Courant Number mean: 1.44865 max: 40989.8
smoothSolver: Solving for Ux, Initial residual = 0.927528, Final residual = 8.93978e06, No Iterations 156
smoothSolver: Solving for Uy, Initial residual = 0.933172, Final residual = 9.00634e06, No Iterations 154
smoothSolver: Solving for Uz, Initial residual = 0.934392, Final residual = 9.09487e06, No Iterations 164
GAMG: Solving for p, Initial residual = 0.269707, Final residual = 1.87423e06, No Iterations 16
time step continuity errors : sum local = 5.44156e06, global = 1.2902e07, cumulative = 1.6054e07
GAMG: Solving for p, Initial residual = 0.01606, Final residual = 1.1425e07, No Iterations 15
time step continuity errors : sum local = 1.22906e05, global = 1.24249e07, cumulative = 2.84789e07
ExecutionTime = 348.32 s ClockTime = 349 s
Time = 3003.1
Courant Number mean: 2.80059 max: 32857.3
smoothSolver: Solving for Ux, Initial residual = 0.938765, Final residual = 9.33157e06, No Iterations 171
smoothSolver: Solving for Uy, Initial residual = 0.934481, Final residual = 9.3031e06, No Iterations 270
smoothSolver: Solving for Uz, Initial residual = 0.935665, Final residual = 9.24883e06, No Iterations 281
GAMG: Solving for p, Initial residual = 0.28984, Final residual = 2.32895e06, No Iterations 15
time step continuity errors : sum local = 1.85582e05, global = 4.94828e08, cumulative = 3.34272e07
GAMG: Solving for p, Initial residual = 0.0101664, Final residual = 8.05664e08, No Iterations 14
time step continuity errors : sum local = 4.56476e05, global = 1.87007e07, cumulative = 5.21278e07
ExecutionTime = 394.82 s ClockTime = 396 s
Time = 3003.2
Courant Number mean: 9.53619 max: 62332.5
smoothSolver: Solving for Ux, Initial residual = 0.884443, Final residual = 8.72835e06, No Iterations 553
smoothSolver: Solving for Uy, Initial residual = 0.890166, Final residual = 8.89899e06, No Iterations 528
smoothSolver: Solving for Uz, Initial residual = 0.889302, Final residual = 8.77769e06, No Iterations 537
GAMG: Solving for p, Initial residual = 0.168963, Final residual = 1.59669e06, No Iterations 15
time step continuity errors : sum local = 6.90831e05, global = 7.5791e07, cumulative = 1.27919e06
GAMG: Solving for p, Initial residual = 0.00349722, Final residual = 2.23965e08, No Iterations 14
time step continuity errors : sum local = 0.000157283, global = 1.18665e06, cumulative = 9.25401e08
ExecutionTime = 491.15 s ClockTime = 492 s
Time = 3003.3
Courant Number mean: 32.9325 max: 112992
smoothSolver: Solving for Ux, Initial residual = 0.881954, Final residual = 0.000100022, No Iterations 1000
smoothSolver: Solving for Uy, Initial residual = 0.887072, Final residual = 6.31404e05, No Iterations 1000
smoothSolver: Solving for Uz, Initial residual = 0.880495, Final residual = 5.62691e05, No Iterations 1000
GAMG: Solving for p, Initial residual = 0.142865, Final residual = 1.09615e06, No Iterations 16
time step continuity errors : sum local = 0.000410075, global = 1.36218e05, cumulative = 1.35293e05
GAMG: Solving for p, Initial residual = 0.0017875, Final residual = 1.2698e08, No Iterations 14
time step continuity errors : sum local = 0.00169306, global = 3.15075e05, cumulative = 1.79783e05
ExecutionTime = 664.65 s ClockTime = 666 s

