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A simple 2D simulation getting stuck with No Error

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Old   December 14, 2014, 11:16
Default A simple 2D simulation getting stuck with No Error
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Hasan K.J.
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Hey FOAMers,

I am having a simple 2D airfoil case I have been trying to do mesh dependency test, but with the same boundary conditions I am getting drastically different Cl, Cd for all the cases with different mesh, I have made the mesh with utmost care. Apart from that few cases with reasonably dense meshes are getting stuck without any error at one iteration what could be the reason. It can't be the computer because the cases are on the HPC.

Code:
Time = 160052

smoothSolver:  Solving for Ux, Initial residual = 1.14095e-05, Final residual = 7.49989e-09, No Iterations 12
smoothSolver:  Solving for Uy, Initial residual = 1.34364e-05, Final residual = 8.83883e-09, No Iterations 12
GAMG:  Solving for p, Initial residual = 5.67128e-05, Final residual = 9.85634e-08, No Iterations 11
time step continuity errors : sum local = 1.98112e-07, global = 3.63618e-14, cumulative = 1.88178e-12
smoothSolver:  Solving for omega, Initial residual = 3.84661e-07, Final residual = 9.65063e-09, No Iterations 6
smoothSolver:  Solving for k, Initial residual = 1.53943e-05, Final residual = 5.46731e-09, No Iterations 13
ExecutionTime = 1227.14 s  ClockTime = 1561 s

forces output:
    forces(pressure, viscous)((-2.20311e+06 5.95228e+07 1.22269e-14) (-30247.5 2173.54 6.53313e-18))
    moment(pressure, viscous)((-5.75432e-17 -2.17177e-16 -8.19743e+06) (-1.38678e-20 1.70345e-18 -683.179))

forceCoeffs output:
    Cd = -248.151
    Cl = 6613.89
    Cm = -1.19707e-19

Time = 160053

smoothSolver:  Solving for Ux, Initial residual = 1.14094e-05, Final residual = 7.49987e-09, No Iterations 12
smoothSolver:  Solving for Uy, Initial residual = 1.34364e-05, Final residual = 8.83881e-09, No Iterations 12

some cases get stuck forever but some cases after couple of hours move the next time step and get stuck there but still the No iterations of was 11 only moreover i also have
Code:
minIter          5;
maxIter          100;
to make sure it is not the no of iterations that is delaying it.

I have no idea why the case is literally getting stuck !!! first time im coming across this problem in 2 years any idea
Thanks for your reply,
Hasan K.J
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Old   December 14, 2014, 12:30
Default Sorry for wasting time
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Hasan K.J.
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If anybody comes across the same problem the problem is the reltol,

I don't know what I was thinking the cases that were getting stuck that I had said had reltol to 0 it was fv sol,schemes from my old cases in which I had changed the reltol as the case was converging but I had used the same reltol to initiate the case here which caused the slow down and getting stuck

now i have changed the reltol to 0.1 will slowly increase it to 0.01, 0.001 etc as the case converges.

changing the relTol solved my problem

Thanks for your time,
Hasan K.J
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