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  1. Old Comment

    blockMesh,snappyMesh and experimental results for 2D airfoil

    Quote:
    Originally Posted by maalan View Comment
    Thank you skeptik! I considered your idea but my ellipse has an aspect ratio equal to 2% (try to plot it and you will understand me), so this is the reason why I decided emulate your O-grid and mesh it by using sHM and adding some layers... So, could you share again your files, please??

    Thank you very much!!
    All the best.
    No matter how big your AR is. This way to build meshes with o-grid block works fine also in case of thin compressor blades.

    I will look for sHM - files. I just wanna to say reduce nLayers and increase minMedianAxisAngle and featureAngle. Your empty patches should be "patches" when you generating coarse and snapped mesh. You should switch to "empty" only when generating layers.

    Any other settings you could see here http://openfoamwiki.net/images/f/f0/...SlidesOFW7.pdf
    permalink
    Posted April 25, 2014 at 07:56 by skeptik skeptik is offline
  2. Old Comment

    blockMesh,snappyMesh and experimental results for 2D airfoil

    Thank you skeptik! I considered your idea but my ellipse has an aspect ratio equal to 2% (try to plot it and you will understand me), so this is the reason why I decided emulate your O-grid and mesh it by using sHM and adding some layers... So, could you share again your files, please??

    Thank you very much!!
    All the best.
    permalink
    Posted April 25, 2014 at 07:36 by maalan maalan is offline
  3. Old Comment

    blockMesh,snappyMesh and experimental results for 2D airfoil

    Quote:
    Originally Posted by maalan View Comment
    My original mesh is a circular cylinder within an O-grid domain. Once applied the Joukowski transformation I get an ellipse within an O-grid conformal mesh. Have a look here, skeptik!!

    https://www.dropbox.com/s/lp2mbo0sz2jblgt/ellipse.pdf
    https://www.dropbox.com/s/jgmjbbv9mlvormu/ellipse2.pdf
    https://www.dropbox.com/s/owr757rkbwi386m/ellipse3.pdf
    You're really smart guy, cause you know about Jukowsky transformation. But i think this way too complicated.

    Just make the o-grid blocks with elliptical edges with attention to edge-to-egde distance and you will have a good mesh to resolve BL.

    https://www.dropbox.com/s/slsu1ek052z011c/ellipse.png

    permalink
    Posted April 25, 2014 at 06:29 by skeptik skeptik is offline
  4. Old Comment

    blockMesh,snappyMesh and experimental results for 2D airfoil

    My original mesh is a circular cylinder within an O-grid domain. Once applied the Joukowski transformation I get an ellipse within an O-grid conformal mesh. Have a look here, skeptik!!

    https://www.dropbox.com/s/lp2mbo0sz2jblgt/ellipse.pdf
    https://www.dropbox.com/s/jgmjbbv9mlvormu/ellipse2.pdf
    https://www.dropbox.com/s/owr757rkbwi386m/ellipse3.pdf
    permalink
    Posted April 24, 2014 at 13:41 by maalan maalan is offline
  5. Old Comment

    blockMesh,snappyMesh and experimental results for 2D airfoil

    Quote:
    Originally Posted by maalan View Comment
    Thanks for your reply, skeptik!! I know what you mean, and up to the moment I tried successfully a conformal mesh from a cylinder mesh (I applied the Joukowski transformation). The point is that my ellipse has 2% aspect ratio, so, assuming the major axis of my ellipse is aligned with the x-axis and the minor axis with the y-axis, i get very thin cells normal to the wall both in the trailing and leading edges and much coarser cells normal to the wall in the middle of my ellips. I'm afraid that my viscous term will not be well solved... What do you think of?? any idea??

    Best!
    what is your blocking structure?
    permalink
    Posted April 24, 2014 at 13:19 by skeptik skeptik is offline
  6. Old Comment

    blockMesh,snappyMesh and experimental results for 2D airfoil

    Thanks for your reply, skeptik!! I know what you mean, and up to the moment I tried successfully a conformal mesh from a cylinder mesh (I applied the Joukowski transformation). The point is that my ellipse has 2% aspect ratio, so, assuming the major axis of my ellipse is aligned with the x-axis and the minor axis with the y-axis, i get very thin cells normal to the wall both in the trailing and leading edges and much coarser cells normal to the wall in the middle of my ellips. I'm afraid that my viscous term will not be well solved... What do you think of?? any idea??

    Best!
    permalink
    Posted April 24, 2014 at 12:56 by maalan maalan is offline
  7. Old Comment

    blockMesh,snappyMesh and experimental results for 2D airfoil

    Quote:
    Originally Posted by maalan View Comment
    Hi skeptik!

    I'm currently trying to simulate the flow over a high aspect ratio ellipse but i am very new with snappyHexMesh and blockMesh. I always imported my meshes from gambit...
    would you mind to repost the snappyhexMeshDict and blockMeshDict you used for this case? The link is no longer available...

    Thanks in advance!
    Best!
    Now i have no sHM files on my computer.. May be tomorrow i'll find it.

    But, ellipse is an analytical surface. You really don't need a sHM utility to build a mesh. Try blockMesh!
    permalink
    Posted April 24, 2014 at 12:27 by skeptik skeptik is offline
  8. Old Comment

    blockMesh,snappyMesh and experimental results for 2D airfoil

    Hi skeptik!

    I'm currently trying to simulate the flow over a high aspect ratio ellipse but i am very new with snappyHexMesh and blockMesh. I always imported my meshes from gambit...
    would you mind to repost the snappyhexMeshDict and blockMeshDict you used for this case? The link is no longer available...

    Thanks in advance!
    Best!
    permalink
    Posted April 24, 2014 at 08:24 by maalan maalan is offline
  9. Old Comment

    God bless America

    Quote:
    Originally Posted by wyldckat View Comment
    Hi skeptik,

    Nice! The courses they have got, also come in handy... so I've added the links for them here: http://openfoamwiki.net/index.php/Ha...ourse-training

    And I think the title for this blog post should be "God bless America and Italy"

    Best regards,
    Bruno
    Great. Thanks, i've posted your link at russian public group.
    permalink
    Posted December 9, 2013 at 03:18 by skeptik skeptik is offline
  10. Old Comment

    God bless America

    Hi skeptik,

    Nice! The courses they have got, also come in handy... so I've added the links for them here: http://openfoamwiki.net/index.php/Ha...ourse-training

    And I think the title for this blog post should be "God bless America and Italy"

    Best regards,
    Bruno
    permalink
    Posted December 8, 2013 at 16:45 by wyldckat wyldckat is offline
  11. Old Comment

    Loosing precision with symmetryPlane

    Quote:
    Originally Posted by lixx View Comment
    Have you had data for slip BC now?
    Problem wasn't in symmetryPlane BC. I think it was local poor mesh quality.
    permalink
    Posted November 27, 2013 at 01:10 by skeptik skeptik is offline
  12. Old Comment

    Loosing precision with symmetryPlane

    Have you had data for slip BC now?
    permalink
    Posted November 25, 2013 at 23:35 by lixx lixx is offline
  13. Old Comment

    Good news about airfoil and OpenFoam

    Quote:
    Originally Posted by Alhasan View Comment
    Hi Ilya,

    Do You have any experience with airfoil LES and Fv schemes and Fv solutions for Airfoil LES

    Thanks,
    Hasan K.J
    I have no experience. But i try to simulate wing in tube.
    I know few good books about LES but only on russian.
    permalink
    Posted November 16, 2013 at 17:07 by skeptik skeptik is offline
  14. Old Comment
    Alhasan's Avatar

    Good news about airfoil and OpenFoam

    Hi Ilya,

    Do You have any experience with airfoil LES and Fv schemes and Fv solutions for Airfoil LES

    Thanks,
    Hasan K.J
    permalink
    Posted November 15, 2013 at 14:44 by Alhasan Alhasan is offline
  15. Old Comment

    Useful article about mesh types

    Thank you. Very nice!
    permalink
    Posted October 17, 2013 at 08:50 by styleworker styleworker is offline
  16. Old Comment

    blockMesh,snappyMesh and experimental results for 2D airfoil

    Archive with case files is here

    https://www.dropbox.com/s/1ih182x44v...appyHex.tar.gz

    There are both snappyHex case and 2Dextrusion case with extrusion dictionary. In the one of this case resulted mesh was saved and archived.

    Enjoy.
    permalink
    Posted April 18, 2013 at 03:13 by skeptik skeptik is offline
  17. Old Comment

    blockMesh,snappyMesh and experimental results for 2D airfoil

    Quote:
    Originally Posted by arming View Comment
    Hi skeptik!

    I'm currently doing some simulations of flow over airfoils, but i have some trouble getting a nice mesh with snappyHexMesh...
    could you please send me your snappyhexMeshDict you used for this case, cause the mesh looks very nice!

    Thank you in advance
    Armin
    eventually it's not a good mesh. I just exceeded amount of files can be loaded to the post. The problem was described here. And i still don not know how to generate good mesh at the tail of the foil.
    permalink
    Posted April 18, 2013 at 01:23 by skeptik skeptik is offline
  18. Old Comment

    blockMesh,snappyMesh and experimental results for 2D airfoil

    Hi skeptik!

    I'm currently doing some simulations of flow over airfoils, but i have some trouble getting a nice mesh with snappyHexMesh...
    could you please send me your snappyhexMeshDict you used for this case, cause the mesh looks very nice!

    Thank you in advance
    Armin
    permalink
    Posted April 17, 2013 at 13:05 by arming arming is offline
  19. Old Comment

    Good news about airfoil and OpenFoam

    Quote:
    Originally Posted by andrei.cimpoeru View Comment
    ok I understand ....... I am sumulating the flow over naca23012 and it is a pain in the ass getting the the solution to converge......I am using wall functions and a High Re 3*e06........I am interested to know about you fvschemes and fvsolutions that you used...
    I will appreciate that.

    Many thanks
    i did not care about convergence cause i have an experimental results to validate my simulation's results.
    If you have coarse mesh, the convergence could be really bad.

    In addition fvSchemes and fvSolutions

    Code:
    ddtSchemes
    {
        default         steadyState;
    }
    
    gradSchemes
    {
        default         Gauss linear;
        grad(p)         Gauss linear;
        //grad(U)         Gauss linear;
        grad(U)         cellLimited Gauss linear 1;
    }
    
    divSchemes
    {
        default         none;
    //    div(phi,U)      Gauss upwind;
        div(phi,U)      Gauss linearUpwindV Gauss linear;
        div(phi,k)      Gauss upwind;
        div(phi,epsilon) Gauss upwind;
        div(phi,R)      Gauss upwind;
        div(R)          Gauss linear;
        div(phi,nuTilda) Gauss upwind;
        div((nuEff*dev(grad(U).T()))) Gauss linear;
    }
    
    laplacianSchemes
    {
        default         Gauss linear limited 0.5; //none;
    /*    laplacian(nuEff,U) Gauss linear corrected;
        laplacian((1|A(U)),p) Gauss linear corrected;
        laplacian(DkEff,k) Gauss linear corrected;
        laplacian(DepsilonEff,epsilon) Gauss linear corrected;
        laplacian(DREff,R) Gauss linear corrected;
        laplacian(DnuTildaEff,nuTilda) Gauss linear corrected;*/
    }
    
    interpolationSchemes
    {
        default         linear;
        interpolate(U)  linear;
    }
    
    snGradSchemes
    {
        default         corrected;
    }
    
    fluxRequired
    {
        default         no;
        p               ;
    }
    Code:
    solvers
    { 
        p
        {
            solver           GAMG;
            tolerance        1e-7;
            relTol           0.1;
            smoother         GaussSeidel;
            nPreSweeps       0;
            nPostSweeps      2;
            cacheAgglomeration on;
            agglomerator     faceAreaPair;
            nCellsInCoarsestLevel 10;
            mergeLevels      1;
        };
    
        U
        {
            solver           smoothSolver;
            smoother         GaussSeidel;
            tolerance        1e-8;
            relTol           0.1;
            nSweeps          1;
        };
    
        k
        {
            solver           smoothSolver;
            smoother         GaussSeidel;
            tolerance        1e-8;
            relTol           0.1;
            nSweeps          1;
            maxIter 100;
            minIter 1;
        };
       
        epsilon
        {
            solver           smoothSolver;
            smoother         GaussSeidel;
            tolerance        1e-8;
            relTol           0.1;
            nSweeps          1;
            maxIter 100;
            minIter 1;
        }
    
        R
        {
            solver           smoothSolver;
            smoother         GaussSeidel;
            tolerance        1e-8;
            relTol           0.1;
            nSweeps          1;
            maxIter 100;
            minIter 1;
        }
    
        nuTilda
        {
            solver           smoothSolver;
            smoother         GaussSeidel;
            tolerance        1e-8;
            relTol           0.1;
            nSweeps          1;
            maxIter 100;
            minIter 1;
        }
    }
    
    SIMPLE
    {
        nNonOrthogonalCorrectors 4;
        pRefCell        0;
        pRefValue       0;
        
        residualControl
        {
            p               1e-5;
            U               1e-5;
            "(k|omega)"     1e-5;
        }
    }
    
    relaxationFactors
    {
        p               0.3;
        U               0.5;
        k               0.7;
        epsilon         0.7;
        R               0.7;
        nuTilda         0.7;
    }
    permalink
    Posted March 21, 2013 at 06:03 by skeptik skeptik is offline
  20. Old Comment

    Good news about airfoil and OpenFoam

    ok I understand ....... I am sumulating the flow over naca23012 and it is a pain in the ass getting the the solution to converge......I am using wall functions and a High Re 3*e06........I am interested to know about you fvschemes and fvsolutions that you used...
    I will appreciate that.

    Many thanks
    permalink
    Posted March 19, 2013 at 16:05 by andrei.cimpoeru andrei.cimpoeru is offline

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