refineWallLayer for reaching y+<1 for low Re number turbulence model
 

Hi:)
Dear foamer i have a big promlem, i want to analysis two turbulence models on 3 element airfoil,
1. high Re number e.g realizableKE ==> 30 <y+ <200
2. low Re number e.g lunderSharmaKE ==> y+ <1
i use snappyHexMesh for meshin the domain aroun the airfoil, and after finishing the analysis with realizableKE, i execute "yPlusRAS" and it told me y+ is:
Time = 3400
Reading field U

Reading/calculating face flux field phi

Selecting incompressible transport model Newtonian
Selecting RAS turbulence model realizableKE
realizableKECoeffs
{
Cmu 0.09;
A0 4;
C2 1.9;
sigmak 1;
sigmaEps 1.2;
}

Patch 5 named main_solid y+ : min: 3.92116 max: 92.2824 average: 41.5749

Patch 6 named flap_solid y+ : min: 11.3159 max: 75.4566 average: 34.844

Patch 7 named slat_solid y+ : min: 17.4322 max: 61.5812 average: 43.726

and the checkMesh for RealizableKE doeasn't complain of skewness and nonOrthogonality,
here it is:
Create polyMesh for time = 3400

Time = 3400

Mesh stats
points: 188346
internal points: 0
faces: 368558
internal faces: 182800
cells: 91461
faces per cell: 6.02834
boundary patches: 8
point zones: 0
face zones: 0
cell zones: 0

Overall number of cells of each type:
hexahedra: 88316
prisms: 584
wedges: 0
pyramids: 0
tet wedges: 0
tetrahedra: 0
polyhedra: 2561
Breakdown of polyhedra by number of faces:
faces number of cells
7 1953
8 603
9 3
10 2

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
topAndBottom 496 996 ok (non-closed singly connected)
inlet 176 354 ok (non-closed singly connected)
outlet 176 354 ok (non-closed singly connected)
front 91461 94173 ok (non-closed singly connected)
back 91461 94173 ok (non-closed singly connected)
main_solid 1298 2596 ok (non-closed singly connected)
flap_solid 376 752 ok (non-closed singly connected)
slat_solid 314 628 ok (non-closed singly connected)

Checking geometry...
Overall domain bounding box (-5.84378 -11.1882 0.15) (20.9289 9.3226 0.250001)
Mesh (non-empty, non-wedge) directions (1 1 0)
Mesh (non-empty) directions (1 1 0)
***Number of edges not aligned with or perpendicular to non-empty directions: 33
<<Writing 30 points on non-aligned edges to set nonAlignedEdges
Boundary openness (4.30491e-19 -2.30373e-20 -1.93086e-13) OK.
Max cell openness = 2.10615e-16 OK.
Max aspect ratio = 6.91795 OK.
Minimum face area = 4.88326e-08. Maximum face area = 0.0100272. Face area magnitudes OK.
Min volume = 4.88326e-09. Max volume = 0.00100272. Total volume = 43.645. Cell volumes OK.
Mesh non-orthogonality Max: 62.2458 average: 3.79811
Non-orthogonality check OK.
Face pyramids OK.
Max skewness = 2.67447 OK.
Coupled point location match (average 0) OK.

Failed 1 mesh checks.

but when i execute refineWallLayer for reaching lower layer thickness near the wall and also lower y+ that was proper for lunderSharmaKE, the checkMesh complain skewness alot.
what should i do?:(:(:(
how should i yeild the low y+ with snappyhexMesh???
please guide me:(

here it is some pics of adding layer to main element
 

here it is some pics of adding layer to the leading edge of main element

here is some pics of adding layer to another element of 3 element airfoil (slat)

here is some pic of slat

Hey, sorry for digging up this old post, but did you resolved the problem?

In a case like this, I would try the generateBoundaryLayers utility of the cfMesh meshing collection. This tool extrudes a new layer of cells inwards, the mesh is shrunk in order to provide the space for the layer. This is similar to the layer addition stage of snappyHexMesh.

refineWallLayer, on the other hand, simply splits the cells next to the wall.