CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > OpenFOAM

strange result for non-orthogonality mesh using icoFoam

Register Blogs Members List Search Today's Posts Mark Forums Read

Reply
 
LinkBack Thread Tools Display Modes
Old   November 1, 2013, 00:08
Default strange result for non-orthogonality mesh using icoFoam
  #1
New Member
 
JM
Join Date: Jul 2013
Posts: 7
Rep Power: 4
xiaof is on a distinguished road
hello everyone
I am simulating a duct flow with icoFoam. I use periodic boundary condition for inlet and outlet.The other boundary condition I set as no-slip.
I have attached the velocity profile here.You can find that there are some velocity jumps which I think affected by the mesh.

The followings are the fvschemes, fvsolution, and the result of the checkMesh.


Thank you in advance.
fvSchemes
Code:
ddtSchemes
{
    default         Euler;
}

gradSchemes
{
      default        cellMDLimited leastSquares 1;
   // grad(p)         Gauss linear;
}

divSchemes
{
     default         none;
    div(phi,U)      Gauss reconCentral cellLimited leastSquares 1.0;
    div(phi)      Gauss linearUpwindV cellMDLimited leastSquares 1.0;

}

laplacianSchemes
{
    default        Gauss linear corrected;
    laplacian(nu,U) Gauss linear corrected;
    laplacian((1|A(U)),p)  Gauss linear corrected;

    laplacian(DT,T)     Gauss linear corrected;
}

interpolationSchemes
{
    default         linear;
   interpolate(HbyA) linear;
  
}

snGradSchemes
{
    default         corrected;
}

fluxRequired
{
    default         no;
    p;
}
fvSolution
Code:
solvers
{
    p
    {
        solver           PCG;
        preconditioner   DIC;
        tolerance        1e-08;
        relTol           0;
    };
   

    U
    {
        solver           PBiCG;
        preconditioner   DILU;
        tolerance        1e-08;
        relTol           0;
    };
  
}

PISO
{
    nCorrectors     3;
    nNonOrthogonalCorrectors 2;
    pRefCell        0;
    pRefValue       0;
}
checkMesh
Code:
Create time

Create polyMesh for time = 0

Time = 0

Mesh stats
    points:           48548
    faces:            119960
    internal faces:   94888
    cells:            35808
    boundary patches: 2
    point zones:      0
    face zones:       0
    cell zones:       0

Overall number of cells of each type:
    hexahedra:     35808
    prisms:        0
    wedges:        0
    pyramids:      0
    tet wedges:    0
    tetrahedra:    0
    polyhedra:     0

Checking topology...
    Boundary definition 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                  
    INTERFACE           1200     1600     ok (non-closed singly connected)  
    inout               23872    24274    ok (non-closed singly connected)  

Checking geometry...
    This is a 3-D mesh
    Overall domain bounding box (-1 -1 -4.33680869e-19) (1 1 0.01999999955)
    Mesh (non-empty, non-wedge) directions (1 1 1)
    Mesh (non-empty) directions (1 1 1)
    Mesh (non-empty, non-wedge) dimensions 3
    Boundary openness (6.5506050833e-20 -8.7921189539e-20 -1.6233662817e-19) Threshold = 1e-06 OK.
    Max cell openness = 2.1714371522e-16 OK.
    Max aspect ratio = 350.00000279 OK.
    Minumum face area = 9.999999e-08. Maximum face area = 0.0011896420623.  Face area magnitudes OK.
    Min volume = 6.6666658486e-10. Max volume = 7.9309469101e-06.  Total volume = 0.0799999982.  Cell volumes OK.
    Mesh non-orthogonality Max: 44.27477573 average: 9.93239561 Threshold = 70
    Non-orthogonality check OK.
    Face pyramids OK.
    Max skewness = 0.57381680369 OK.

Mesh OK.

End

xiaof
Attached Images
File Type: jpg mesh.jpg (97.1 KB, 22 views)
File Type: jpg v.jpg (75.6 KB, 24 views)
xiaof is offline   Reply With Quote

Old   November 2, 2013, 08:48
Default
  #2
nsf
Member
 
Nicolas Edh
Join Date: Mar 2010
Location: Uppsala, Sweden
Posts: 85
Rep Power: 7
nsf is on a distinguished road
Hi xiof,

I don't have any indepth knowledge of the schemes you are using but I would try to switch to a second order time stepping scheme like backward or CrankNicolson.

Secondly are you sure that the velocity jump isn't an artifact of the warping? Is it still there if you make a a linear plot?

Best
Nicolas
nsf is offline   Reply With Quote

Reply

Tags
non-orthogonality

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
SnappyHexMesh for internal Flow vishwa OpenFOAM Native Meshers: snappyHexMesh and Others 23 August 6, 2014 03:50
2D Mesh Generation Tutorial for GMSH aeroslacker Open Source Meshers: Gmsh, Netgen, CGNS, ... 12 January 19, 2012 04:52
Accuracy problem of HO schemes on unstructured mesh, HO scheme gives 1st order result gemini Main CFD Forum 12 December 27, 2011 22:01
[ICEM] Unstructure Meshing Around Imported Plot3D Structured Mesh ICEM kawamatt2 ANSYS Meshing & Geometry 17 December 20, 2011 12:45
engrid -> save as .stl with boundarie codes Zymon enGrid 31 August 29, 2011 13:40


All times are GMT -4. The time now is 19:43.