[sandri_92]

Hello world !

I’ve been keeping an eye on the forum since a few days, when a problem has stopped my current analysis of a F1 car in OpenFoam… It was all running fine until I got into trouble, and it is called Floating point exception ! As much as I could read here and with my own conclusions, it is a problem in solving the simulation, some forces starts to increase to infinite and there becomes the trouble. I suppose it is a bad config of the 0 folder, however this exercises are just a mere copy of a modified motorbike tutorial, to suit my goals. Also I have run this simulation before, using this configuration with 11M and 8M elements, and it all were fine…

I copy the error for you to see if it is possible to solve it (how can I?), then I write the details.


Log.simplefoam:

.
  .
  Time = 16
   
  smoothSolver:  Solving for Ux, Initial residual = 0.4577433, Final residual = 0.049488617, No Iterations 89
  smoothSolver:  Solving for Uy, Initial residual = 0.50514958, Final residual = 0.045692466, No Iterations 111
  smoothSolver:  Solving for Uz, Initial residual = 0.54803684, Final residual = 0.05058686, No Iterations 99
  GAMG:  Solving for p, Initial residual = 0.99997705, Final residual = 0.045319146, No Iterations 4
  time step continuity errors : sum local = 5.724511e+22, global = -2.0239651e+19, cumulative = -2.0239691e+19
  smoothSolver:  Solving for omega, Initial residual = 0.0018840911, Final residual = 0.0018840911, No Iterations 0
  smoothSolver:  Solving for k, Initial residual = 0.12713486, Final residual = 0.010924944, No Iterations 4
  ExecutionTime = 1531.99 s  ClockTime = 1587 s
   
  forceCoeffs FC_all write:
      Cm    = 4.4527335e+38
      Cd    = 2.2644272e+38
      Cl    = -3.1365293e+38
      Cl(f) = 2.8844689e+38
      Cl(r) = -6.0209981e+38
   
  forceCoeffs FC_DF write:
      Cm    = -8.6279513e+36
      Cd    = 1.8271275e+35
      Cl    = 3.0221822e+36
      Cl(f) = -7.1168602e+36
      Cl(r) = 1.0139042e+37
   
  forceCoeffs FC_FW write:
      Cm    = -3.9464373e+35
      Cd    = -3.8710834e+35
      Cl    = 8.5864521e+35
      Cl(f) = 3.467888e+34
      Cl(r) = 8.2396633e+35
   
  forceCoeffs FC_RW write:
      Cm    = -1.6720172e+34
      Cd    = -6.7760632e+32
      Cl    = 3.3563058e+33
      Cl(f) = -1.5042019e+34
      Cl(r) = 1.8398325e+34
   
  forceCoeffs FC_MC write:
      Cm    = -6.9842379e+36
      Cd    = 2.0477325e+36
      Cl    = 4.0989468e+36
      Cl(f) = -4.9347645e+36
      Cl(r) = 9.0337113e+36
   
  forceCoeffs FC_FT write:
      Cm    = 4.6200689e+38
      Cd    = 2.2455591e+38
      Cl    = -3.2199196e+38
      Cl(f) = 3.0101091e+38
      Cl(r) = -6.2300287e+38
   
  forceCoeffs FC_RT write:
      Cm    = -3.6955346e+35
      Cd    = 3.9559462e+34
      Cl    = 8.4964137e+34
      Cl(f) = -3.2707139e+35
      Cl(r) = 4.1203553e+35
   
  forceCoeffs FC_FS write:
      Cm    = -3.2520765e+35
      Cd    = -5.4436352e+33
      Cl    = 2.6467591e+35
      Cl(f) = -1.9286969e+35
      Cl(r) = 4.575456e+35
   
  forceCoeffs FC_RS write:
      Cm    = -1.1199115e+34
      Cd    = 2.4305181e+33
      Cl    = 2.7576384e+33
      Cl(f) = -9.8202954e+33
      Cl(r) = 1.2577934e+34
   
  forceCoeffs FC_HM write:
      Cm    = -3.3366807e+33
      Cd    = 7.6042636e+33
      Cl    = 3.3570304e+33
      Cl(f) = -1.6581655e+33
      Cl(r) = 5.0151959e+33
   
  forceCoeffs FC_MS write:
      Cm    = -6.9195888e+32
      Cd    = 8.0411046e+30
      Cl    = 1.4585541e+32
      Cl(f) = -6.1903117e+32
      Cl(r) = 7.6488659e+32
   
  forces F_all write:
      sum of forces:
          pressure : (5.5478467e+40 4.7693711e+41 -7.6844967e+40)
          viscous  : (-5.2084616e+23 2.7371834e+24 1.4683138e+24)
          porous   : (0 0 0)
      sum of moments:
          pressure : (-2.2639604e+41 1.0909197e+41 5.2415948e+41)
          viscous  : (6.0845954e+23 -1.8867381e+24 3.7820324e+24)
          porous   : (0 0 0)
   
  forces F_DF write:
      sum of forces:
          pressure : (4.4764624e+37 1.5554199e+38 7.4043465e+38)
          viscous  : (3.0718397e+20 -4.8158765e+19 2.6805852e+19)
          porous   : (0 0 0)
      sum of moments:
          pressure : (1.2705452e+39 -2.1138481e+39 2.8288225e+38)
          viscous  : (5.0873584e+19 -4.173384e+19 -6.2600578e+20)
          porous   : (0 0 0)
   
  forces F_FW write:
      sum of forces:
          pressure : (-9.4841542e+37 -1.4490273e+38 2.1036808e+38)
          viscous  : (-8.509648e+21 -8.5489268e+20 2.6137722e+21)
          porous   : (0 0 0)
      sum of moments:
          pressure : (3.3877115e+38 -9.6687713e+37 5.6202687e+37)
          viscous  : (3.9632255e+21 -2.5455955e+21 1.4065171e+22)
          porous   : (0 0 0)
   
  forces F_MC write:
      sum of forces:
          pressure : (5.0169446e+38 1.5739133e+39 1.004242e+39)
          viscous  : (-8.6441911e+21 5.3699526e+20 9.6584024e+21)
          porous   : (0 0 0)
      sum of moments:
          pressure : (1.2975152e+39 -1.7111383e+39 1.8464863e+39)
          viscous  : (1.6914593e+22 -1.0897105e+22 1.7843728e+22)
          porous   : (0 0 0)
   
  forces F_RW write:
      sum of forces:
          pressure : (-1.6601355e+35 -1.1157278e+36 8.2229493e+35)
          viscous  : (2.5444248e+18 -2.4638871e+17 4.2237586e+18)
          porous   : (0 0 0)
      sum of moments:
          pressure : (2.2067933e+36 -4.0964422e+36 -5.083615e+36)
          viscous  : (6.9600611e+18 -1.8908935e+19 -5.3236883e+18)
          porous   : (0 0 0)
   
  Time = 17
   
  smoothSolver:  Solving for Ux, Initial residual = 0.65619427, Final residual = 7.0498179, No Iterations 1000
  smoothSolver:  Solving for Uy, Initial residual = 0.69676997, Final residual = 5.9391165, No Iterations 1000
  smoothSolver:  Solving for Uz, Initial residual = 0.69566693, Final residual = 7.7600318, No Iterations 1000
  [5] #0  Foam::error::printStack(Foam::Ostream&) at ??:?
  [5] #1  Foam::sigFpe::sigHandler(int) at ??:?
  [5] #2  ? in "/lib/x86_64-linux-gnu/libc.so.6"
  [5] #3  Foam::GaussSeidelSmoother::smooth(Foam::word const&, Foam::Field<double>&, Foam::lduMatrix const&, Foam::Field<double> const&, Foam::FieldField<Foam::Field, double> const&, Foam::UPtrList<Foam::lduInterfaceField const> const&, unsigned char, int) at ??:?
  [5] #4  Foam::GaussSeidelSmoother::smooth(Foam::Field<double>&, Foam::Field<double> const&, unsigned char, int) const at ??:?
  [5] #5  Foam::GAMGSolver::Vcycle(Foam::PtrList<Foam::lduMatrix::smoother> const&, Foam::Field<double>&, Foam::Field<double> const&, Foam::Field<double>&, Foam::Field<double>&, Foam::Field<double>&, Foam::Field<double>&, Foam::Field<double>&, Foam::PtrList<Foam::Field<double> >&, Foam::PtrList<Foam::Field<double> >&, unsigned char) const at ??:?
  [5] #6  Foam::GAMGSolver::solve(Foam::Field<double>&, Foam::Field<double> const&, unsigned char) const at ??:?
  [5] #7  Foam::fvMatrix<double>::solveSegregated(Foam::dictionary const&) at ??:?
  [5] #8  Foam::fvMatrix<double>::solve(Foam::dictionary const&) at ??:?
  [5] #9  Foam::fvMatrix<double>::solve() at ??:?
  [5] #10  ? at ??:?
  [5] #11  __libc_start_main in "/lib/x86_64-linux-gnu/libc.so.6"
  [5] #12  ? at ??:?
  [ubuntu:04458] *** Process received signal ***
  [ubuntu:04458] Signal: Floating point exception (8)
  [ubuntu:04458] Signal code:  (-6)
  [ubuntu:04458] Failing at address: 0x3e80000116a
  [ubuntu:04458] [ 0] /lib/x86_64-linux-gnu/libc.so.6(+0x354a0)[0x7f1a8f6094a0]
  [ubuntu:04458] [ 1] /lib/x86_64-linux-gnu/libc.so.6(gsignal+0x38)[0x7f1a8f609418]
  [ubuntu:04458] [ 2] /lib/x86_64-linux-gnu/libc.so.6(+0x354a0)[0x7f1a8f6094a0]
  [ubuntu:04458] [ 3] /opt/openfoam4/platforms/linux64GccDPInt32Opt/lib/libOpenFOAM.so(_ZN4Foam19GaussSeidelSmoother6smoothERKNS_4wordERNS_5FieldIdEERKNS_9lduMatrixERKS5_RKNS_10FieldFieldIS4_dEERKNS_8UPtrListIKNS_17lduInterfaceFieldEEEhi+0x42d)[0x7f1a9085788d]
  [ubuntu:04458] [ 4] /opt/openfoam4/platforms/linux64GccDPInt32Opt/lib/libOpenFOAM.so(_ZNK4Foam19GaussSeidelSmoother6smoothERNS_5FieldIdEERKS2_hi+0x28)[0x7f1a90857c98]
  [ubuntu:04458] [ 5] /opt/openfoam4/platforms/linux64GccDPInt32Opt/lib/libOpenFOAM.so(_ZNK4Foam10GAMGSolver6VcycleERKNS_7PtrListINS_9lduMatrix8smootherEEERNS_5FieldIdEERKS8_S9_S9_S9_S9_S9_RNS1_IS8_EESD_h+0x93d)[0x7f1a9087552d]
  [ubuntu:04458] [ 6] /opt/openfoam4/platforms/linux64GccDPInt32Opt/lib/libOpenFOAM.so(_ZNK4Foam10GAMGSolver5solveERNS_5FieldIdEERKS2_h+0x86d)[0x7f1a90877cfd]
  [ubuntu:04458] [ 7] /opt/openfoam4/platforms/linux64GccDPInt32Opt/lib/libfiniteVolume.so(_ZN4Foam8fvMatrixIdE15solveSegregatedERKNS_10dictionaryE+0x15b)[0x7f1a929d395b]
  [ubuntu:04458] [ 8] simpleFoam(_ZN4Foam8fvMatrixIdE5solveERKNS_10dictionaryE+0x191)[0x468e51]
  [ubuntu:04458] [ 9] simpleFoam(_ZN4Foam8fvMatrixIdE5solveEv+0xd4)[0x4690a4]
  [ubuntu:04458] [10] simpleFoam[0x422d25]
  [ubuntu:04458] [11] /lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xf0)[0x7f1a8f5f4830]
  [ubuntu:04458] [12] simpleFoam[0x4248e9]
  [ubuntu:04458] *** End of error message ***
  --------------------------------------------------------------------------
  mpirun noticed that process rank 5 with PID 4458 on node ubuntu exited on signal 8 (Floating point exception).
   
  #END OF LOG.SIMPLEFOAM

My exercise:
Simulate half a F1 car using kOmegaSST turbulence model, at 20m/s.
Boundary conditions:
-DF: Diffuser, a wall
-FW: Front wing, a wall
-RW: Rear wing, a wall
-MC: Monocoque, a wall
-HM: Helmet, a wall
-MS: Monkeyseat, a wall
-FS: Front suspension, a wall
-RS: Rear suspension, a wall
-FT: Front tire, rotating wall
-RT: Rear tire, rotating wall

blockMeshDict:
-Sym1: symmetric plane
-movwall: tarmarc, moving at constant velocity, 20m/s
-slipwall and slipwallFR: upper and front patches, slip walls.
-inlet and outlet

Mesh seems not to have any problem, except for some skew faces.

I attached my case files, the original one that worked perfectly, and the case A_1 and A_2. In case A_1 the mesh is a little bit more refined and the FW .stl file has changed (result: 11M elements). In the A_2 the mesh is even more refined, but the problem is the same (15M elements).

If more information is needed, please tell me.


I beg your pardon, I know this is a common issue, but I don't have a real clue on how to solve it, or why the case A works properly and the other 2 don't ... I've also added some screenshots for you to see the geometry and some post process.