[Pierpaolo]

Hi all,
I have a problem with a plane heat exchanger (HE) whose performances I would like to evaluate.
The convergence is never reached and I get the error reported at the end of this post.
I see that the Courant number kind of explodes but I own up to it that despite the efforts in rummaging through the configurations files and changing several different values of the timestep, grid coarsenes and BC, I am not able to find a way out without the help of someone more experienced.
Attached is the case dir and all needed is to type in:
Allrun 0.0001

Thanks for any help and suggestion.

The HE is composed of 4 layers (dx=1mm;dy=180mm;dz=10.2mm):
1 topFluid (hot air incoming at 340K)
1 topSolid
1 bottomFluid (cold air incoming at 300K)
1 bottomSolid
Bottom face of the bottom solid has cyclic bc with top face of the top fluid.

Error:
---- snip ----
Solving for fluid region bottomFluid
diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
DILUPBiCG: Solving for Uy, Initial residual = 0.03538927, Final residual = 1.971183e-11, No Iterations 3
DILUPBiCG: Solving for Uz, Initial residual = 0.00460497, Final residual = 9.836213e-09, No Iterations 2
DILUPBiCG: Solving for h, Initial residual = 0.004765986, Final residual = 9.041913e-12, No Iterations 3
Min/max T:299.7815 340.039
GAMG: Solving for p, Initial residual = 0.05313307, Final residual = 0.0004813086, No Iterations 27
diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
time step continuity errors (bottomFluid): sum local = 2.280073e-06, global = 1.180403e-07, cumulative = -4.329433e-06
GAMG: Solving for p, Initial residual = 0.000516105, Final residual = 9.573149e-09, No Iterations 129
diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
time step continuity errors (bottomFluid): sum local = 4.981507e-11, global = -3.992155e-12, cumulative = -4.329437e-06

Solving for fluid region topFluid
diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
DILUPBiCG: Solving for Uy, Initial residual = 0.02129376, Final residual = 5.564677e+08, No Iterations 1001
DILUPBiCG: Solving for Uz, Initial residual = 0.02065763, Final residual = 5.061882e-09, No Iterations 5
DILUPBiCG: Solving for h, Initial residual = 0.004138133, Final residual = 7.869983e-09, No Iterations 3
Min/max T:299.9864 380
GAMG: Solving for p, Initial residual = 1, Final residual = 0.009861178, No Iterations 55
diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
time step continuity errors (topFluid): sum local = -0.1170467, global = -0.007092308, cumulative = -0.00708989
GAMG: Solving for p, Initial residual = 0.8161496, Final residual = 0.263601, No Iterations 1000
diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
time step continuity errors (topFluid): sum local = -43.27072, global = 0.9988777, cumulative = 0.9917878

Solving for solid region bottomSolid
DICPCG: Solving for T, Initial residual = 0.002423304, Final residual = 7.526829e-09, No Iterations 1
DICPCG: Solving for T, Initial residual = 7.488132e-09, Final residual = 7.488132e-09, No Iterations 0
Min/max T:min(T) [0 0 0 1 0 0 0] 339.9409 max(T) [0 0 0 1 0 0 0] 340

Solving for solid region topSolid
DICPCG: Solving for T, Initial residual = 0.005851229, Final residual = 4.241606e-07, No Iterations 1
DICPCG: Solving for T, Initial residual = 4.215058e-07, Final residual = 4.215058e-07, No Iterations 0
Min/max T:min(T) [0 0 0 1 0 0 0] 339.9823 max(T) [0 0 0 1 0 0 0] 340
ExecutionTime = 56.08 s ClockTime = 56 s

Region: bottomFluid Courant Number mean: 0.004116788 max: 0.1663119
Region: topFluid Courant Number mean: -318763 max: 7.685058e+08
#0 Foam::error:rintStack(Foam::Ostream&) in "/home/pier/OpenFOAM/OpenFOAM-1.6.x/lib/linuxGccDPOpt/libOpenFOAM.so"
#1 Foam::sigFpe::sigFpeHandler(int) in "/home/pier/OpenFOAM/OpenFOAM-1.6.x/lib/linuxGccDPOpt/libOpenFOAM.so"
#2 Uninterpreted:
#3 Foam::Time::adjustDeltaT() in "/home/pier/OpenFOAM/OpenFOAM-1.6.x/lib/linuxGccDPOpt/libOpenFOAM.so"
#4 Foam::Time::setDeltaT(double) in "/home/pier/OpenFOAM/OpenFOAM-1.6.x/lib/linuxGccDPOpt/libOpenFOAM.so"
#5 main in "/home/pier/OpenFOAM/OpenFOAM-1.6.x/applications/bin/linuxGccDPOpt/chtMultiRegionFoam"
#6 __libc_start_main in "/lib/libc.so.6"
#7 Foam::regIOobject::writeObject(Foam::IOstream::str eamFormat, Foam::IOstream::versionNumber, Foam::IOstream::compressionType) const in "/home/pier/Op
M/OpenFOAM-1.6.x/applications/bin/linuxGccDPOpt/chtMultiRegionFoam"
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