[rogibear]

Hi, I'm trying to run a very simple ahmed body case with low Reynolds number (100 & 1000) with time steps of 0.001 & 0.0001 for each case. The mesh is pretty course so I'm not expecting to get useable results but I am trying to get the simulation to complete. The problem is the courant number keeps increasing >1 by the timestep doesn't seem to have much effect on it.

see below:

Courant Number mean: 0.000359148 max: 0.793021
DILUPBiCG:  Solving for Ux, Initial residual = 0.923248, Final residual = 3.32352e-09, No Iterations 2
DILUPBiCG:  Solving for Uy, Initial residual = 0.969197, Final residual = 2.0091e-09, No Iterations 2
DILUPBiCG:  Solving for Uz, Initial residual = 0.930231, Final residual = 9.23342e-10, No Iterations 2
DICPCG:  Solving for p, Initial residual = 0.17526, Final residual = 9.82767e-07, No Iterations 146
time step continuity errors : sum local = 6.91405e-09, global = 4.97837e-12, cumulative = -4.69581e-09
DICPCG:  Solving for p, Initial residual = 0.000412786, Final residual = 8.75322e-07, No Iterations 77
time step continuity errors : sum local = 6.42496e-09, global = 1.81337e-10, cumulative = -4.51448e-09
ExecutionTime = 1028.69 s  ClockTime = 1031 s

Time = 0.0351

Courant Number mean: 0.000366532 max: 0.7604
DILUPBiCG:  Solving for Ux, Initial residual = 0.969019, Final residual = 3.0867e-09, No Iterations 2
DILUPBiCG:  Solving for Uy, Initial residual = 0.969175, Final residual = 1.89008e-09, No Iterations 2
DILUPBiCG:  Solving for Uz, Initial residual = 0.935075, Final residual = 1.67906e-09, No Iterations 2
DICPCG:  Solving for p, Initial residual = 0.174915, Final residual = 9.83657e-07, No Iterations 146
time step continuity errors : sum local = 7.24729e-09, global = -5.65332e-12, cumulative = -4.52013e-09
DICPCG:  Solving for p, Initial residual = 0.000413647, Final residual = 9.5122e-07, No Iterations 35
time step continuity errors : sum local = 7.31108e-09, global = -4.48088e-10, cumulative = -4.96822e-09
ExecutionTime = 1032.19 s  ClockTime = 1034 s

Time = 0.0352

Courant Number mean: 0.000373678 max: 0.872445
DILUPBiCG:  Solving for Ux, Initial residual = 0.925273, Final residual = 4.64637e-09, No Iterations 2
DILUPBiCG:  Solving for Uy, Initial residual = 0.968993, Final residual = 2.77035e-09, No Iterations 2
DILUPBiCG:  Solving for Uz, Initial residual = 0.930175, Final residual = 1.26008e-09, No Iterations 2
DICPCG:  Solving for p, Initial residual = 0.174619, Final residual = 9.7952e-07, No Iterations 146
time step continuity errors : sum local = 7.55802e-09, global = 5.9816e-12, cumulative = -4.96224e-09
DICPCG:  Solving for p, Initial residual = 0.000445268, Final residual = 9.10332e-07, No Iterations 77
time step continuity errors : sum local = 7.3276e-09, global = 2.08616e-10, cumulative = -4.75362e-09
ExecutionTime = 1035.99 s  ClockTime = 1038 s

Time = 0.0353

Courant Number mean: 0.000381645 max: 0.818073
DILUPBiCG:  Solving for Ux, Initial residual = 0.96842, Final residual = 4.16886e-09, No Iterations 2
DILUPBiCG:  Solving for Uy, Initial residual = 0.968974, Final residual = 2.53332e-09, No Iterations 2
DILUPBiCG:  Solving for Uz, Initial residual = 0.935703, Final residual = 2.32248e-09, No Iterations 2
DICPCG:  Solving for p, Initial residual = 0.174293, Final residual = 9.80834e-07, No Iterations 146
time step continuity errors : sum local = 7.92459e-09, global = -6.76192e-12, cumulative = -4.76038e-09
DICPCG:  Solving for p, Initial residual = 0.000447096, Final residual = 9.42898e-07, No Iterations 35
time step continuity errors : sum local = 7.94622e-09, global = -3.75958e-10, cumulative = -5.13634e-09
ExecutionTime = 1039.07 s  ClockTime = 1041 s

Time = 0.0354

Courant Number mean: 0.000389596 max: 0.960098
DILUPBiCG:  Solving for Ux, Initial residual = 0.927154, Final residual = 6.49988e-09, No Iterations 2
DILUPBiCG:  Solving for Uy, Initial residual = 0.968825, Final residual = 3.79038e-09, No Iterations 2
DILUPBiCG:  Solving for Uz, Initial residual = 0.930027, Final residual = 2.14034e-09, No Iterations 2
DICPCG:  Solving for p, Initial residual = 0.174019, Final residual = 9.76577e-07, No Iterations 146
time step continuity errors : sum local = 8.26213e-09, global = 7.12199e-12, cumulative = -5.12922e-09
DICPCG:  Solving for p, Initial residual = 0.000480689, Final residual = 9.48658e-07, No Iterations 77
time step continuity errors : sum local = 8.37163e-09, global = 2.40243e-10, cumulative = -4.88898e-09
ExecutionTime = 1042.65 s  ClockTime = 1045 s

Time = 0.0355

Courant Number mean: 0.000398198 max: 0.877074
DILUPBiCG:  Solving for Ux, Initial residual = 0.967843, Final residual = 5.58373e-09, No Iterations 2
DILUPBiCG:  Solving for Uy, Initial residual = 0.968759, Final residual = 3.34602e-09, No Iterations 2
DILUPBiCG:  Solving for Uz, Initial residual = 0.936349, Final residual = 3.19647e-09, No Iterations 2
DICPCG:  Solving for p, Initial residual = 0.17371, Final residual = 9.78324e-07, No Iterations 146
time step continuity errors : sum local = 8.66548e-09, global = -8.01879e-12, cumulative = -4.897e-09
DICPCG:  Solving for p, Initial residual = 0.000483549, Final residual = 9.38136e-07, No Iterations 35
time step continuity errors : sum local = 8.66638e-09, global = -2.75065e-10, cumulative = -5.17206e-09
ExecutionTime = 1045.74 s  ClockTime = 1048 s

Time = 0.0356

Courant Number mean: 0.000407007 max: 1.06032
DILUPBiCG:  Solving for Ux, Initial residual = 0.928911, Final residual = 9.04348e-09, No Iterations 2
DILUPBiCG:  Solving for Uy, Initial residual = 0.968677, Final residual = 5.06989e-09, No Iterations 2
DILUPBiCG:  Solving for Uz, Initial residual = 0.929783, Final residual = 6.0862e-09, No Iterations 2
DICPCG:  Solving for p, Initial residual = 0.173457, Final residual = 9.73925e-07, No Iterations 146
time step continuity errors : sum local = 9.032e-09, global = 8.40815e-12, cumulative = -5.16365e-09
DICPCG:  Solving for p, Initial residual = 0.000519323, Final residual = 9.90508e-07, No Iterations 77
time step continuity errors : sum local = 9.58036e-09, global = 2.7687e-10, cumulative = -4.88678e-09
ExecutionTime = 1049.41 s  ClockTime = 1051 s

If you need me to upload the full case I'll put a dropbox link up.

Thanks,

Adam