foam-extend 4.1 GGI check
 

Hello Folks


I'm working with foam-extend simulating a Francis turbine and I have problems to get a solution.



In the CAD the surfaces composing the interfaces perfectly match each other.

After meshed (discretization error) the differences between areas at the interfaces are:

Spiral-GuideVanes: Diff = -1.54116647556601e-05
Bulb-DraftTube: Diff = 2.25976241261805e-05


According to your experience, is it enough an area difference of O(e-05) for GGI (or mixing plane) interfaces?



Bests

This should not be a problem - compare the error in area between the two surfaces with respect to the flux error.


Can you post the whole message?

Thank you for reply Prof. Jasak.

The message is the following:



GGI pair (SP-GV, GV-SP)
Area: 0.254671269026831 0.254686680691586 Diff = -1.54116647556601e-05 or 0.00605122525991961 %
Flux: 0.949992608907554 0.950088338717345 Diff = -9.57298097908899e-05 or 0.010075885145599 %
GGI pair (BULB-DT, DT-BULB)
Area: 0.138815526804067 0.138792929179941 Diff = 2.25976241261805e-05 or 0.0162788879936147 %
Flux: 0.972494692318502 0.972510217271029 Diff = -1.55249525264356e-05 or 0.0015963793748101 %


Regarding the last interface (mixing-plane) the mixing plane check is not working in parallel (this can be verified also running the tutorial "axialTurbine_mixingPlane").



I made the grids using Numeca AG5 and Omnis. The checkMesh looks fine.




Create time

Create polyMesh for time = 0

Initializing the GGI interpolator between master/shadow patches: SP-GV/GV-SP
Initializing the GGI interpolator between master/shadow patches: BULB-DT/DT-BULB
Time = 0

Mesh stats
all points: 22230489
live points: 13966149
all faces: 46481093
live faces: 38339883
internal faces: 35820020
cells: 12196229
boundary patches: 27
point zones: 0
face zones: 6
cell zones: 4

Overall number of cells of each type:
hexahedra: 11986443
prisms: 0
wedges: 0
pyramids: 0
tet wedges: 0
tetrahedra: 0
polyhedra: 209786

Checking topology...
Boundary definition OK.
Point usage OK.
Upper triangular ordering OK.
Face vertices OK.
*Number of regions: 4
The mesh has multiple regions which are not connected by any face.
<<Writing region information to "0/cellToRegion"
Nuumber of cells per region:
0 330992
1 0
2 0
3 0


Checking geometry...
This is a 3-D mesh
Overall domain bounding box (-0.7879466659 -1.671217118 -0.2864486732) (0.8220821991 4.442373826 3.74207617)
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 (-7.36175726854743e-13 -2.65983934844024e-12 2.58673887309245e-12) Threshold = 1e-06 OK.
Max cell openness = 5.15135387404077e-08 OK.
Max aspect ratio = 267.233167283032 OK.
Minumum face area = 3.35187928762322e-09. Maximum face area = 0.011201607594839. Face area magnitudes OK.
Min volume = 3.13556677637343e-12. Max volume = 0.00116740721267175. Total volume = 3.08841375862224. Cell volumes OK.
Mesh non-orthogonality Max: 72.648044449205 average: 18.5441847118136 Threshold = 70
*Number of severely non-orthogonal faces: 22.
Non-orthogonality check OK.
Writing 22 non-orthogonal faces to set nonOrthoFaces
Face pyramids OK.
Max skewness = 2.77047715280581 OK.

Mesh OK.

End

Hi, did you use the ggi interface in parallel mode ? I find the initialization takes too much time when I use ggi interface in parallel? Do I need to decompose the mesh in another way ? Thanks!