Naca0012 incorrect lift coefficient for attack angle 10 degrees

[jremington]

Thanks for posting this automated run generator for OpenFOAM!

This seemed promising, so I ran the NACA0012 airfoil case with fine mesh and angles of attack of 0 and 10 degrees, and checked to see how well it reproduced accepted results for drag and lift coefficients, e.g. as discussed here: https://www.openfoam.com/documentation/guides/latest/doc/verification-validation-naca0012-airfoil-2d.html

Unfortunately, in my hands it does not. These are the values I got

Attack Cd CL
0 0.004 10^-22 (OK)
10 0.004 -0.001 (should be positive and about 1.0)

Please check!

[jremington]

I went back, checked the result and found at least one the problems. The mesh is XZ, but the boundary conditions for the velocity field U assume an XY mesh, so the angle of attack is applied along the wrong axis. Common mistake.

How was the mesh generated? It has a very low yPlus value and could be useful.

Log of complete run, if anyone is interested:

C:\Users\Jim\Desktop\OpenFOAMCaseGenerator-main>python3 OpenFOAMCaseGenerator.py --case=Naca0012 -p:angle_of_attack=10 -p:mesh=fine
Application    : OpenFOAMCaseGenerator
Source         : https://github.com/tomrobin-teschner/OpenFOAMCaseGenerator
Copyright      : Tom-Robin Teschner, 2020-2025
License        : MIT
Version        : 3.0.0beta.2

Generated case : Naca0012
Using input    : input/cases/Naca0012/Naca0012.py

Case parameters
  - run_in_parallel      : False
  - number_of_processors : 1
  - reynolds_number      : 6000000
  - angle_of_attack      : 10
  - rans_model           : RansModel.kOmegaSST
  - mesh                 : fine

>>>moved folder Naca0012 to linux subsystem

jim@Jims-9010:~/tutorial$ cd Naca0012/
jim@Jims-9010:~/tutorial/Naca0012$ ls
0.orig  Allclean  Allrun  Naca0012.foam  constant  postProcessing  system

jim@Jims-9010:~/tutorial/Naca0012$ checkMesh
/*---------------------------------------------------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  2412                                  |
|   \\  /    A nd           | Website:  www.openfoam.com                      |
|    \\/     M anipulation  |                                                 |
\*---------------------------------------------------------------------------*/
Build  : _f00230df-20250528 OPENFOAM=2412 patch=250528 version=2412
Arch   : "LSB;label=32;scalar=64"
Exec   : checkMesh
Date   : Sep 02 2025
Time   : 11:38:03
Host   : Jims-9010
PID    : 1700
I/O    : uncollated
Case   : /home/jim/tutorial/Naca0012
nProcs : 1
trapFpe: Floating point exception trapping enabled (FOAM_SIGFPE).
fileModificationChecking : Monitoring run-time modified files using timeStampMaster (fileModificationSkew 5, maxFileModificationPolls 20)
allowSystemOperations : Allowing user-supplied system call operations

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
Create time

--> FOAM Warning :
    From static Foam::instantList Foam::timeSelector::select0(Foam::Time&, const Foam::argList&)
    in file db/Time/timeSelector.C at line 284
    No time specified or available, selecting 'constant'
Create mesh for time = constant

Check mesh...

Time = constant

Mesh stats
    points:           115648
    internal points:  0
    faces:            229856
    internal faces:   114208
    cells:            57344
    faces per cell:   6
    boundary patches: 3
    point zones:      0
    face zones:       0
    cell zones:       0

Overall number of cells of each type:
    hexahedra:     57344
    prisms:        0
    wedges:        0
    pyramids:      0
    tet wedges:    0
    tetrahedra:    0
    polyhedra:     0

Checking topology...
    Boundary definition OK.
    Cell to face addressing OK.
    Point usage OK.
    Upper triangular ordering OK.
    Face vertices OK.
    Number of regions: 1 (OK).

Checking patch topology for multiply connected surfaces...
    Patch               Faces    Points     Surface topology
    BaseAndTop          114688   115648   ok (non-closed singly connected)
    airfoil             256      512      ok (non-closed singly connected)
    farfield            704      1408     ok (non-closed singly connected)
    ".*"                115648   115648   ok (closed singly connected)


Checking faceZone topology for multiply connected surfaces...
    No faceZones found.

Checking basic cellZone addressing...
    No cellZones found.

Checking basic pointZone addressing...
    No pointZones found.

Checking geometry...
    Overall domain bounding box (-484.457 -1 -507.806) (501 0 507.806)
    Mesh has 2 geometric (non-empty/wedge) directions (1 0 1)
    Mesh has 2 solution (non-empty) directions (1 0 1)
    All edges aligned with or perpendicular to non-empty directions.
    Boundary openness (-3.07762e-19 -6.92209e-15 3.07762e-19) OK.
 ***High aspect ratio cells found, Max aspect ratio: 2.98998e+07, number of cells 7320
  <<Writing 7320 cells with high aspect ratio to set highAspectRatioCells
    Minimum face area = 5.18207e-10. Maximum face area = 3181.85.  Face area magnitudes OK.
    Min volume = 5.18207e-10. Max volume = 3181.85.  Total volume = 875555.  Cell volumes OK.
    Mesh non-orthogonality Max: 53.6952 average: 5.03415
    Non-orthogonality check OK.
    Face pyramids OK.
    Max skewness = 0.341413 OK.
    Coupled point location match (average 0) OK.

Failed 1 mesh checks.

End


jim@Jims-9010:~/tutorial/Naca0012$ ./Allrun > Naca0012.log
Restore 0/ from 0.orig/
Traceback (most recent call last):
  File "/home/jim/tutorial/Naca0012/postProcessing/plotResiduals.py", line 2, in <module>
    import matplotlib.pyplot as plt
ModuleNotFoundError: No module named 'matplotlib'
Traceback (most recent call last):
  File "/home/jim/tutorial/Naca0012/postProcessing/addVTPLoader.py", line 24, in <module>
    main()
  File "/home/jim/tutorial/Naca0012/postProcessing/addVTPLoader.py", line 7, in main
    assert len(sys.argv) > 1, 'Need at least one plane to process'
           ^^^^^^^^^^^^^^^^^
AssertionError: Need at least one plane to process
Traceback (most recent call last):
  File "/home/jim/tutorial/Naca0012/postProcessing/addVTPLoader.py", line 24, in <module>
    main()
  File "/home/jim/tutorial/Naca0012/postProcessing/addVTPLoader.py", line 7, in main
    assert len(sys.argv) > 1, 'Need at least one plane to process'
           ^^^^^^^^^^^^^^^^^
AssertionError: Need at least one plane to process
jim@Jims-9010:~/tutorial/Naca0012$ gedit Naca0012.log

LAST LINES OF LOG FILE

runTimeControl runTimeControl1 output:
    runTimeControl: condition1 averages:
        CdMean: 0.0078953, delta: 9.73394e-06
        ClMean: -0.00139215, delta: 1.71636e-06

    average: condition1 condition satisfied
    Stopping calculation
    Writing fields

forceCoeffs forceCoeffs write:
    Coefficient	Total	Pressure	Viscous	Internal
    Cd:	0.00790503	0.00149315	0.00641188	0
    Cd(f):	0.00393106	0.000725115	0.00320594	0
    Cd(r):	0.00397398	0.000768038	0.00320594	0
    Cl:	-0.00139387	-0.000263283	-0.00113059	0
    Cl(f):	-0.00471043	-0.000889735	-0.00382069	0
    Cl(r):	0.00331656	0.000626452	0.0026901	0
    CmPitch:	-0.00401349	-0.000758094	-0.0032554	0
    CmRoll:	-2.14605e-05	-2.14616e-05	1.05141e-09	0
    CmYaw:	-1.09211e-06	-1.12798e-06	3.58636e-08	0
    Cs:	-4.18897e-05	-4.18793e-05	-1.03844e-08	0
    Cs(f):	-2.20369e-05	-2.20676e-05	3.06714e-08	0
    Cs(r):	-1.98527e-05	-1.98117e-05	-4.10558e-08	0

    writing force and moment coefficient files.

runTimeControl runTimeControl2 output:
    maxDuration: conditions1
        Completed 0.526316 out of 1e-07
    maxDuration: conditions1 condition satisfied
    Setting trigger 1

    functionObjects::pressure pressureCoefficient writing field: cp
yPlus yPlus write:
    writing field yPlus
    patch airfoil y+ : min = 0.0464249, max = 0.285007, average = 0.206792

runTimeControl runTimeControl2 output:
    maxDuration: conditions1
        Completed 0 out of 1e-07
    Conditions not met

    functionObjects::pressure pressureCoefficient writing field: cp
yPlus yPlus write:
    writing field yPlus
    patch airfoil y+ : min = 0.0464249, max = 0.285007, average = 0.206792
End

>>> Writing VTP loader for []

Contents of file 0/U (boundary conditions):

jim@Jims-9010:~/tutorial/Naca0012/0$ cat U
/*--------------------------------*- C++ -*----------------------------------*\
| =========                 |                                                 |
| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
|  \\    /   O peration     | Version:  v2212                                 |
|   \\  /    A nd           | Web:      www.OpenFOAM.com                      |
|    \\/     M anipulation  |                                                 |
|                                                                             |
| This file was automatically generated using the OpenFOAMCaseGenerator       |
| see https://github.com/tomrobin-teschner/OpenFOAMCaseGenerator              |
|                                                                             |
\*---------------------------------------------------------------------------*/

FoamFile
{
    version     2.0;
    format      ascii;
    class       volVectorField;
    location    "0";
    object      U;
}

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

dimensions      [0 1 -1 0 0 0 0];

internalField   uniform (5.908846518073248 1.041889066001582 0.0);

boundaryField
{
    airfoil
    {
        type            noSlip;
    }
    farfield
    {
        type            freestreamVelocity;
        freestreamValue uniform (5.908846518073248 1.041889066001582 0.0);
    }
    BaseAndTop
    {
        type            empty;
    }
}

// ************************************************************************* //

[tomrobin-teschner]

sorry for being a bit unresponsive, and thanks for flagging this. I'll have a look and patch this, once done, I'll note it here and close the issue once fixed.