|
[Sponsors] |
December 24, 2016, 13:19 |
Wing external flow (tutorial)
|
#1 |
New Member
Paul
Join Date: Dec 2016
Posts: 2
Rep Power: 0 |
Dear all,
I'm new to OF 3.0.x, coming from realms of lifting line theories and panel method. My goal is to study wing/wake interference in both OF and 3D panel method. I wonder, if there is any tutorial for external flow over 3D wings or airplane. A common practice in aerospace is to make a spherical domain around the object (wing) and prescribe freestream (farfield) BC on the boundary. So far I have found only tutorials, where the domain is a box corresponding to a wind tunnel. All of these tutorial are working for me, but are quite useless in aerospace world since we need to change angle of attack and side slip angle. So I decided to make my own tutorial: I have a rectangular wing with l=6000mm, c=1000mm and NACA 0010 airfoil. I created a spherical domain with R=15000mm around the wing with freestream and frestreamPressure BC. Running simpleFoam with laminar turbulence model, after 200 iterations it gives for alpha=5.7deg CL=0.39, CM=-0.09, which I consider as realistic. Panel method gives for the same case CL=0.42 So far so good, but when I try to run potentialFoam, it ends with sigFpe error: Code:
Calculating potential flow #0 Foam::error::printStack(Foam::Ostream&) at ??:? #1 Foam::sigFpe::sigHandler(int) at ??:? #2 ? in "/lib/x86_64-linux-gnu/libc.so.6" #3 Foam::adjustPhi(Foam::GeometricField<double, Foam::fvsPatchField, Foam::surfaceMesh>&, Foam::GeometricField<Foam::Vector<double>, Foam::fvPatchField, Foam::volMesh> const&, Foam::GeometricField<double, Foam::fvPatchField, Foam::volMesh>&) at ??:? Floating point exception Best regards Paul p: Code:
/*--------------------------------*- C++ -*----------------------------------*\ | ========= | | | \\ / F ield | OpenFOAM: The Open Source CFD Toolbox | | \\ / O peration | Version: 3.0.x | | \\ / A nd | Web: www.OpenFOAM.org | | \\/ M anipulation | | \*---------------------------------------------------------------------------*/ FoamFile { version 2.0; format ascii; class volScalarField; object p; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // dimensions [0 2 -2 0 0 0 0]; internalField uniform 0; boundaryField { FREE { type freestreamPressure; value uniform 0; } SYM { type symmetryPlane; } WING { type zeroGradient; } } // ************************************************************************* // Code:
/*--------------------------------*- C++ -*----------------------------------*\ | ========= | | | \\ / F ield | OpenFOAM: The Open Source CFD Toolbox | | \\ / O peration | Version: 3.0.x | | \\ / A nd | Web: www.OpenFOAM.org | | \\/ M anipulation | | \*---------------------------------------------------------------------------*/ FoamFile { version 2.0; format ascii; class volVectorField; object U; } // * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * // dimensions [0 1 -1 0 0 0 0]; internalField uniform (10 0 1); boundaryField { FREE { type freestream; freestreamValue uniform (10 0 1); } SYM { type symmetryPlane; } WING { // type fixedValue; // value uniform (0. 0. 0.); type slip; } } // ************************************************************************* // |
|
December 25, 2016, 15:43 |
potentialFoam bug?
|
#2 |
New Member
Paul
Join Date: Dec 2016
Posts: 2
Rep Power: 0 |
After a day spent trying to fix the problem, I'm thinking about a bug in potential foam. When I set a "traditional wind tunnel" BCs:
Code:
inlet: U - fixed value, p - zero gradient outlet: U - zero gradient, p - fixed value When i set BCs of the spherical boundary: Code:
U: type freestream; freestreamValue uniform (10 0 1); p: type freestreamPressure; value uniform 0; Code:
potentialFlow { nNonOrthogonalCorrectors 20; PhiRefCell 0; PhiRefValue 0; } Maybe I'm missing something important, but the fact that I can run the case using simpleFoam and get realistic results, points me to an idea that potentialFoam can not handle this type of mixed BC. Please do you have any ideas to solve the case using potentialFoam? |
|
September 10, 2017, 18:10 |
|
#3 |
New Member
Terence Annarelli
Join Date: Aug 2017
Location: France
Posts: 7
Rep Power: 9 |
Hi, I have no - for now - idea about why potentialfoam does not handle these mixed BC, but as I am working these days on an aeronautic problem, I īm very interested in your spherical domain. I had many problems these days trying to set properly a wind tunnel with AoA and slip angle which vary. Could you hint me about the method you used in order to create the spherical domain please ? with Blockmesh it seems difficult .
I plan to test it with a NACA 2418 wing for which I have "real" lift and drag coefficients. I am of course willing to help you and investigate simplefoam and potentialfoam for my case. Thanks in advance for your help ! Sent from my iPhone using CFD Online Forum mobile app |
|
September 16, 2017, 16:49 |
|
#4 |
New Member
Terence Annarelli
Join Date: Aug 2017
Location: France
Posts: 7
Rep Power: 9 |
About the potentialFoam crash, it seems I had the same problem until I set up some reference values in fvSolution file.
Using this post : --> FOAM FATAL IO ERROR: Unable to set reference cell for field p Please supply |
|
Tags |
external flow |
Thread Tools | Search this Thread |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
CGNS Compiling | Diego | Main CFD Forum | 17 | December 21, 2014 02:40 |
Particle-Laden Flow Tutorial | alan81 | Siemens | 13 | May 17, 2011 15:45 |
How do I select solver options for external flow over an aircraft by fluent? | hadieliasi | FLUENT | 5 | May 2, 2011 04:54 |
Wing lift in Solidwork Flow Simulation | brianmcv | Main CFD Forum | 6 | April 11, 2011 09:16 |
External Flow Pressure | Meri | CFX | 2 | May 6, 2004 11:36 |