[ronaldo]

please anyone, can you help me to model the drag coeffient of a 2D cylinder using Openfoam! I use icoFoam with CrankNicholson o.5 time integration scheme and i became the result below:

Time = 2.4164
Courant Number mean: 0.000625962 max: 0.018118
DILUPBiCG: Solving for Ux, Initial residual = 8.58266e-05, Final residual = 5.68787e-12, No Iterations 1
DILUPBiCG: Solving for Uy, Initial residual = 0.000135717, Final residual = 1.58934e-11, No Iterations 1
DICPCG: Solving for p, Initial residual = 0.000318544, Final residual = 2.92359e-06, No Iterations 10
DICPCG: Solving for p, Initial residual = 6.1916e-06, Final residual = 9.84286e-07, No Iterations 47
DICPCG: Solving for p, Initial residual = 1.54247e-06, Final residual = 7.8343e-07, No Iterations 1
DICPCG: Solving for p, Initial residual = 7.89665e-07, Final residual = 7.89665e-07, No Iterations 0
time step continuity errors : sum local = 8.41203e-15, global = 1.5953e-15, cumulative = -1.07022e-10
DICPCG: Solving for p, Initial residual = 8.12457e-07, Final residual = 8.12457e-07, No Iterations 0
DICPCG: Solving for p, Initial residual = 8.12457e-07, Final residual = 8.12457e-07, No Iterations 0
DICPCG: Solving for p, Initial residual = 8.12457e-07, Final residual = 8.12457e-07, No Iterations 0
DICPCG: Solving for p, Initial residual = 8.12457e-07, Final residual = 8.12457e-07, No Iterations 0
time step continuity errors : sum local = 8.65482e-15, global = 1.59517e-15, cumulative = -1.0702e-10
ExecutionTime = 25803.5 s ClockTime = 77443 s
forces output:
forces(pressure, viscous)((3.36771 -0.00561273 9.48494e-20) (0.365782 -2.56185e-05 -1.76796e-22))
moment(pressure, viscous)((3.44194e-19 -8.53456e-18 -0.263345) (-8.875e-22 1.48343e-20 0.0157597))
forceCoeffs output:
Cd = 152.388
Cl = -0.230137
Cm = -1.91412e-17
Time = 2.4166
Courant Number mean: 0.000625962 max: 0.0181183
DILUPBiCG: Solving for Ux, Initial residual = 8.58272e-05, Final residual = 5.68766e-12, No Iterations 1
DILUPBiCG: Solving for Uy, Initial residual = 0.000135717, Final residual = 1.5893e-11, No Iterations 1
DICPCG: Solving for p, Initial residual = 0.000307771, Final residual = 3.04239e-06, No Iterations 14
DICPCG: Solving for p, Initial residual = 5.71835e-06, Final residual = 9.44935e-07, No Iterations 174
DICPCG: Solving for p, Initial residual = 1.83437e-06, Final residual = 8.73055e-07, No Iterations 1
DICPCG: Solving for p, Initial residual = 8.84112e-07, Final residual = 8.84112e-07, No Iterations 0
time step continuity errors : sum local = 9.41649e-15, global = -2.7658e-16, cumulative = -1.0702e-10
DICPCG: Solving for p, Initial residual = 8.94637e-07, Final residual = 8.94637e-07, No Iterations 0
DICPCG: Solving for p, Initial residual = 8.94637e-07, Final residual = 8.94637e-07, No Iterations 0
DICPCG: Solving for p, Initial residual = 8.94637e-07, Final residual = 8.94637e-07, No Iterations 0
DICPCG: Solving for p, Initial residual = 8.94637e-07, Final residual = 8.94637e-07, No Iterations 0
time step continuity errors : sum local = 9.5286e-15, global = -2.7731e-16, cumulative = -1.07021e-10
ExecutionTime = 25806.4 s ClockTime = 77452 s
forces output:
forces(pressure, viscous)((3.37787 -0.0101397 9.47906e-20) (0.365779 -2.56295e-05 -1.76913e-22))
moment(pressure, viscous)((3.4472e-19 -8.52938e-18 -0.624579) (-8.87876e-22 1.48437e-20 0.0157587))
forceCoeffs output:
Cd = 152.802
Cl = -0.41491
Cm = -1.91296e-17
Time = 2.4168
Courant Number mean: 0.000625962 max: 0.0181186
DILUPBiCG: Solving for Ux, Initial residual = 8.58271e-05, Final residual = 5.68736e-12, No Iterations 1
DILUPBiCG: Solving for Uy, Initial residual = 0.000135717, Final residual = 1.58931e-11, No Iterations 1
DICPCG: Solving for p, Initial residual = 0.000308555, Final residual = 2.98446e-06, No Iterations 6
DICPCG: Solving for p, Initial residual = 5.6599e-06, Final residual = 9.87842e-07, No Iterations 193
DICPCG: Solving for p, Initial residual = 1.97131e-06, Final residual = 8.93472e-07, No Iterations 1
DICPCG: Solving for p, Initial residual = 9.0792e-07, Final residual = 9.0792e-07, No Iterations 0
time step continuity errors : sum local = 9.67148e-15, global = -1.15687e-16, cumulative = -1.07021e-10
DICPCG: Solving for p, Initial residual = 9.19959e-07, Final residual = 9.19959e-07, No Iterations 0
DICPCG: Solving for p, Initial residual = 9.19959e-07, Final residual = 9.19959e-07, No Iterations 0
DICPCG: Solving for p, Initial residual = 9.19959e-07, Final residual = 9.19959e-07, No Iterations 0
DICPCG: Solving for p, Initial residual = 9.19959e-07, Final residual = 9.19959e-07, No Iterations 0
time step continuity errors : sum local = 9.79972e-15, global = -1.14472e-16, cumulative = -1.07021e-10
ExecutionTime = 25809.3 s ClockTime = 77462 s
forces output:
forces(pressure, viscous)((3.36459 -0.00234243 9.49148e-20) (0.365777 -2.56403e-05 -1.76832e-22))
moment(pressure, viscous)((3.41853e-19 -8.54044e-18 -0.00215479) (-8.87561e-22 1.48373e-20
0.0157578))
forceCoeffs output:
Cd = 152.26
Cl = -0.0966561
Cm = -1.91544e-17
Time = 2.417
Courant Number mean: 0.000625962 max: 0.018119
DILUPBiCG: Solving for Ux, Initial residual = 8.58282e-05, Final residual = 5.68722e-12, No Iterations 1
DILUPBiCG: Solving for Uy, Initial residual = 0.000135717, Final residual = 1.58931e-11, No Iterations 1
DICPCG: Solving for p, Initial residual = 0.000315884, Final residual = 2.95918e-06, No Iterations 8
DICPCG: Solving for p, Initial residual = 6.17492e-06, Final residual = 9.82022e-07, No Iterations 76
DICPCG: Solving for p, Initial residual = 1.57902e-06, Final residual = 7.6317e-07, No Iterations 1
DICPCG: Solving for p, Initial residual = 7.70554e-07, Final residual = 7.70554e-07, No Iterations 0
time step continuity errors : sum local = 8.20779e-15, global = 9.71976e-16, cumulative = -1.0702e-10
DICPCG: Solving for p, Initial residual = 7.8575e-07, Final residual = 7.8575e-07, No Iterations 0
DICPCG: Solving for p, Initial residual = 7.8575e-07, Final residual = 7.8575e-07, No Iterations 0
DICPCG: Solving for p, Initial residual = 7.8575e-07, Final residual = 7.8575e-07, No Iterations 0
DICPCG: Solving for p, Initial residual = 7.8575e-07, Final residual = 7.8575e-07, No Iterations 0
time step continuity errors : sum local = 8.36965e-15, global = 9.71832e-16, cumulative = -1.07019e-10
ExecutionTime = 25811 s ClockTime = 77468 s
forces output:
forces(pressure, viscous)((3.37494 -0.0119856 9.47646e-20) (0.365774 -2.56513e-05 -1.76846e-22))
moment(pressure, viscous)((3.43041e-19 -8.5271e-18 -0.772271) (-8.87594e-22 1.48385e-20 0.0157568))
forceCoeffs output:
Cd = 152.682
Cl = -0.490257
Cm = -1.91245e-17
Time = 2.4172
Courant Number mean: 0.000625962 max: 0.0181193
DILUPBiCG: Solving for Ux, Initial residual = 8.58281e-05, Final residual = 5.68692e-12, No Iterations 1
DILUPBiCG: Solving for Uy, Initial residual = 0.000135718, Final residual = 1.58931e-11, No Iterations 1
DICPCG: Solving for p, Initial residual = 0.000308469, Final residual = 2.89403e-06, No Iterations 6
DICPCG: Solving for p, Initial residual = 5.61796e-06, Final residual = 9.72727e-07, No Iterations 52
DICPCG: Solving for p, Initial residual = 1.42823e-06, Final residual = 6.66354e-07, No Iterations 1
DICPCG: Solving for p, Initial residual = 6.7216e-07, Final residual = 6.7216e-07, No Iterations 0
time step continuity errors : sum local = 7.1595e-15, global = 1.21748e-15, cumulative = -1.07018e-10
DICPCG: Solving for p, Initial residual = 6.85686e-07, Final residual = 6.85686e-07, No Iterations 0
DICPCG: Solving for p, Initial residual = 6.85686e-07, Final residual = 6.85686e-07, No Iterations 0
DICPCG: Solving for p, Initial residual = 6.85686e-07, Final residual = 6.85686e-07, No Iterations 0
DICPCG: Solving for p, Initial residual = 6.85686e-07, Final residual = 6.85686e-07, No Iterations 0
time step continuity errors : sum local = 7.30358e-15, global = 1.21697e-15, cumulative = -1.07017e-10
ExecutionTime = 25812.6 s ClockTime = 77472 s
forces output:
forces(pressure, viscous)((3.37343 -0.00605809 9.48554e-20) (0.365771 -2.56622e-05 -1.76854e-22))
moment(pressure, viscous)((3.41449e-19 -8.5356e-18 -0.298624) (-8.87587e-22 1.48391e-20 0.0157559))
forceCoeffs output:
Cd = 152.621
Cl = -0.248316
Cm = -1.91435e-17
Time = 2.4174
Courant Number mean: 0.000625962 max: 0.0181196
DILUPBiCG: Solving for Ux, Initial residual = 8.58283e-05, Final residual = 5.68666e-12, No Iterations 1
DILUPBiCG: Solving for Uy, Initial residual = 0.000135718, Final residual = 1.58931e-11, No Iterations 1
DICPCG: Solving for p, Initial residual = 0.000310674, Final residual = 2.96383e-06, No Iterations 6
DICPCG: Solving for p, Initial residual = 5.80902e-06, Final residual = 9.64652e-07, No Iterations 179
DICPCG: Solving for p, Initial residual = 1.91265e-06, Final residual = 8.68626e-07, No Iterations 1
DICPCG: Solving for p, Initial residual = 8.80374e-07, Final residual = 8.80374e-07, No Iterations 0
time step continuity errors : sum local = 9.37581e-15, global = 7.32662e-17, cumulative = -1.07017e-10
DICPCG: Solving for p, Initial residual = 8.93729e-07, Final residual = 8.93729e-07, No Iterations 0
DICPCG: Solving for p, Initial residual = 8.93729e-07, Final residual = 8.93729e-07, No Iterations 0
DICPCG: Solving for p, Initial residual = 8.93729e-07, Final residual = 8.93729e-07, No Iterations 0
DICPCG: Solving for p, Initial residual = 8.93729e-07, Final residual = 8.93729e-07, No Iterations 0
time step continuity errors : sum local = 9.51804e-15, global = 7.31233e-17, cumulative = -1.07016e-10
ExecutionTime = 25815.3 s ClockTime = 77481 s
forces output:
forces(pressure, viscous)((3.36891 -0.00403213 9.48363e-20) (0.365769 -2.56731e-05 -1.7698e-22))
moment(pressure, viscous)((3.40287e-19 -8.53412e-18 -0.136958) (-8.8798e-22 1.48492e-20 0.0157549))
forceCoeffs output:
Cd = 152.436

Cl = -0.165625

Why are the focesCoefficient still so high?
The function looks like:

type forceCoeffs;
functionObjectLibs ("libforces.so");
log yes;
outputControl timeStep;
outputInterval 1;
patches (patch7);
rhoInf 1.225;
CofR (0.08 0.055 0);// Cylinder-origin
liftDir (0 1 0);
dragDir (1 0 0);
pitchAxis (0 0.08 0);// Axis across the Cylinder
magUInf 2;// equal =Inlet_Velocity=2m/s
lRef 1;
writePrecision 3;

please could someone help me waht i did wrong? It´s very important.

I also did the Simulation with simpleFoam but nothing change!
I would be grateful if anyone has a step by step guide on how i should model this problem, please note I'm not an expert on Openfoam, as I've only just started using it recently.