[mehulsasvadiya1996@gmail.]

Hello to all

I got some different values of cl and cd snd pressure as well. My case is a 2D airfoil; the flow comes from a downward Y direction to the upward Y. U=10.5 m/s and moving wall boundary condition. this is my pimple simulation file

ExecutionTime = 39151.23 s  ClockTime = 40502 s

forceCoeffs forces execute:
    Coefficients
        Cd       : -132.7221	(pressure: -133.06389	viscous: 0.34178725)
        Cs       : 1.6577795e-16	(pressure: 1.6569721e-16	viscous: 8.0738118e-20)
        Cl       : 303.84677	(pressure: 303.33214	viscous: 0.51462964)
        CmRoll       : 1.202228	(pressure: 1.2001917	viscous: 0.0020362308)
        CmPitch       : 22.873064	(pressure: 22.553154	viscous: 0.31990978)
        CmYaw       : 0.52514043	(pressure: 0.52649277	viscous: -0.0013523468)
        Cd(f)    : -65.158823
        Cd(r)    : -67.563278
        Cs(f)    : 0.52514043
        Cs(r)    : -0.52514043
        Cl(f)    : 174.79645
        Cl(r)    : 129.05032
streamLine streamLine1 write:
    seeded 0 particles
    Tracks:0
    Total samples:0
continuityError continuityError1 write:
    local = 2.0707245e-11
    global = 2.4884514e-14
    cumulative = -3.2172443e-12

    functionObjects::vorticity vorticity writing field: vorticityField
yPlus yPlus write:
    writing field yPlus
    patch airfoil y+ : min = 0.23817668, max = 154.31507, average = 52.044156
fieldAverage fieldAverage1 write:
    Calculating averages

    Writing average fields

End

Please check it and tell me where I am wrong?

[night-hawk]

The simple answer is your simulation is diverging. If that is not the case then you have used wrong boundary or initial conditions.

[mehulsasvadiya1996@gmail.]

Originally Posted by night-hawk

The simple answer is your simulation is diverging. If that is not the case then you have used wrong boundary or initial conditions.

Thanks for reply.

How can I know that my initial boundary or boundary condition is wrong?
please check my boundary file

6
(
    left
    {
        type            cyclicAMI;
        inGroups        1(cyclicAMI);
        nFaces          715;
        startFace       138650;
        matchTolerance  0.0001;
        transform       unknown;
        neighbourPatch  right;
        AMIMethod       faceAreaWeightAMI;
        restartUncoveredSourceFace 1;
    }
    right
    {
        type            cyclicAMI;
        inGroups        1(cyclicAMI);
        nFaces          715;
        startFace       139365;
        matchTolerance  0.0001;
        transform       unknown;
        neighbourPatch  left;
        AMIMethod       faceAreaWeightAMI;
        restartUncoveredSourceFace 1;
    }
    inlet
    {
        type            patch;
        nFaces          80;
        startFace       140080;
    }
    outlet
    {
        type            patch;
        nFaces          80;
        startFace       140160;
    }
    airfoil
    {
        type            wall;
        inGroups        1(wall);
        nFaces          310;
        startFace       140240;
    }
    leftRight
    {
        type            empty;
        inGroups        1(empty);
        nFaces          139600;
        startFace       140550;
    }
)

Thanks

[night-hawk]

Can you show your model in diagram? I have just noticed that y+ value is very high (assuming you are using a low- Reynolds Turbulence Model).

[mehulsasvadiya1996@gmail.]

Originally Posted by night-hawk

Can you show your model in diagram? I have just noticed that y+ value is very high (assuming you are using a low- Reynolds Turbulence Model).

Thanks for reply.

Which diagram do u want to see?

[night-hawk]

The model you are using for simulation.

[mehulsasvadiya1996@gmail.]

Originally Posted by night-hawk

The model you are using for simulation.

Thanks

Can you send me your Email-ID? I will send you the whole file and you can check it.

[mehulsasvadiya1996@gmail.]

Originally Posted by mehulsasvadiya1996@gmail.

Thanks

Can you send me your Email-ID? I will send you the whole file and you can check it.

I have attached file here please check it

[night-hawk]

I am not sure what you trying to achieve, your Inlet has normal in x direction but it has velocity value in y direction. Are you trying to rotate airfoil to change angles of attack?

[mehulsasvadiya1996@gmail.]

Originally Posted by night-hawk

I am not sure what you trying to achieve, your Inlet has normal in x direction but it has velocity value in y direction. Are you trying to rotate airfoil to change angles of attack?

Thanks!!!

My inlet is IN Y-direction upward and outlet is top od Y-direction and have moving wall left and right as mentioned in blockMesh. I am not trying to change AOA.

Thanks

[night-hawk]

Are you using dynamic mesh in your simulation?

[mehulsasvadiya1996@gmail.]

Originally Posted by night-hawk

Are you using dynamic mesh in your simulation?

No, I am using cyclicAMI.

[mehulsasvadiya1996@gmail.]

Originally Posted by night-hawk

Are you using dynamic mesh in your simulation?

Hello Sir,

Have you checked my files? Where am I wrong?

[night-hawk]

One thing I noticed is nut value is 0 in initial condition. I would choose it 0.1 times of nu. Since you are not using dynamic Mesh there is no point in using AMI Interpolation. It just add additional computation cost. Last thing I will suggest is reducing max Co in controlDict to 5 from 20.

[mehulsasvadiya1996@gmail.]

Originally Posted by night-hawk

One thing I noticed is nut value is 0 in initial condition. I would choose it 0.1 times of nu. Since you are not using dynamic Mesh there is no point in using AMI Interpolation. It just add additional computation cost. Last thing I will suggest is reducing max Co in controlDict to 5 from 20.

Thanks for reply!!!!

I have periodic boundary the left and right walls. Do u think I should use MRF Property? I still do not understand why I can not use AMI interpolation? Thanks

[night-hawk]

You can use periodic boundary condition for that. AMI and MRF are mainly used when mesh motion is involved.

[mehulsasvadiya1996@gmail.]

Originally Posted by night-hawk

You can use periodic boundary condition for that. AMI and MRF are mainly used when mesh motion is involved.

Thanks

That is why I used CyclicAMI as a periodic boundary condition.

[night-hawk]

I am talking about this https://www.openfoam.com/documentati...ed-cyclic.html


Here you can get more Info periodic set up - cyclicAMI

[mehulsasvadiya1996@gmail.]

Originally Posted by night-hawk

I am talking about this https://www.openfoam.com/documentati...ed-cyclic.html


Here you can get more Info periodic set up - cyclicAMI

Thanks

After reading this I have not found any wrong with my Boundary conditions. Have you seen anything wrong?

[night-hawk]

I don't understand why are using cyclic boundary condition? Your simulation involves measuring Cd and Cl on a airfoil. Anyways you probably need to edit nut initial condition and run the simulation. And also add log file of your simulation if you encounter any error it helps a lot.