[andrei.cimpoeru]

Can anyone tell me how an ideal block topology of an aerofoil mesh looks like. There are various types of grids like O, C and H and I am struggling to get an good aerofoil mesh.
I had a go on the C mesh but i am getting a lot of non orthogonal faces combined with big skew number. Anyone any idea ?

[andrei.cimpoeru]

Hi

I am trying to create an aerofoil mesh using blockMesh but I am getting bad distribution around my leading edge. I am struggling to get orthogonality on the
leading edge.......

Any ideas about how the geometry should look like?

[andrei.cimpoeru]

Has anyone an idea how a blockmesh structure for an aerofoil looks like.......I tried different blocking strategies but I am getting high skew number.

I appreciate any suggestions.

Thanks

[andrei.cimpoeru]

hi there

i want to know if in openfoam is possible to get rid of the nonorthogonal faces .... below i have my mesh which failed to checkMesh
i'll appreciate your help


Create time

Create polyMesh for time = 0

Time = 0

Mesh stats
points: 8250
internal points: 0
faces: 16028
internal faces: 7780
cells: 3968
boundary patches: 5
point zones: 0
face zones: 0
cell zones: 0

Overall number of cells of each type:
hexahedra: 3968
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
inlet 32 66 ok (non-closed singly connected)
outlet 124 250 ok (non-closed singly connected)
topAndBottom 124 250 ok (non-closed singly connected)
Airfoil 32 66 ok (non-closed singly connected)
frontAndBack 7936 8250 ok (non-closed singly connected)

Checking geometry...
Overall domain bounding box (-10 -10.0078 0) (0.30998 0 0.1)
Mesh (non-empty, non-wedge) directions (1 1 1)
Mesh (non-empty) directions (1 1 1)
Boundary openness (-7.55518e-19 8.54205e-19 -2.26297e-16) OK.
Max cell openness = 2.19942e-16 OK.
Max aspect ratio = 65.8488 OK.
Minumum face area = 1.94491e-05. Maximum face area = 0.386396. Face area magnitudes OK.
Min volume = 1.94491e-06. Max volume = 0.0386396. Total volume = 8.19545. Cell volumes OK.
Mesh non-orthogonality Max: 73.7915 average: 7.97915
*Number of severely non-orthogonal faces: 3.
Non-orthogonality check OK.
<<Writing 3 non-orthogonal faces to set nonOrthoFaces
Face pyramids OK.
Max skewness = 2.56447 OK.
Coupled point location match (average 0) OK.

Mesh OK.

End

[wyldckat]

Greetings Andrei,

I'm a bit late on this, but I've merged your questions into a single thread.

AFAIK, doing an aerofoil directly in blockMesh is a very complicated work of art! I'm not familiar with any tutorial that does this, but I do know the following:

• There is a modified blockMesh variant available, designed specifically for these kinds of geometry: http://www.cfd-online.com/Forums/ope...odynamics.html
• You can try SwiftBlock: http://openfoamwiki.net/index.php/Contrib/SwiftBlock
• Here is a tutorial on how to use Blender for creating an STL geometry compatible with snappyHexMesh: http://openfoamwiki.net/index.php/Tut_andrew_blender
• You can try SwiftSnap as well: http://openfoamwiki.net/index.php/Contrib/SwiftSnap
• There is also a possibility to generate a mesh through code, as exemplified in the tutorial "basic/potentialFoam/cylinder".

As for the last error you were getting, it would be easier to help you if you shared a simple example on how to recreate this problem.

Best regards,
Bruno

[colinB]

Hi Andrei, Hi Bruno,

AFAIK, doing an aerofoil directly in blockMesh is a very complicated work of
art!

According to my experience this is not true Bruno.
I managed to create a NACA0012 in blockMesh which was actually rather
simple.

Here is a link to a thread, which also contains the answer to your last question:

- http://www.cfd-online.com/Forums/ope...-naca0012.html

post #5 has an example blockMeshDict which gives you a basic idea.

In a nut shell:

- use c-type mesh
- use any offset calculator which is around on the internet for calculating
an offset of your airfoil
- use polyLine in your blockMeshDict to introduce your foil into the mesh

I hope I could contribute

regards

[MadsR]

Would my airfoilmesher help you?

http://hvirvel.dk/airfoilmesher/

/Mads

[elmo555]

This website provides a small Octave script that directly generates a blockMeshDict for a C-type mesh for any NACA airfoil:
https://www.hpc.ntnu.no/display/hpc/...l+Calculations

I find it to be quite useful. I'll upload it here, in case the URL changes (GNU General Public License).