CFD Online Discussion Forums - [Other] what means information checkMesh give?

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what means information checkMesh give?

Hi
what does mean boundary openness and Max cell openness?
is this mesh OK? aspect ratio till what value is acceptable?

Code:

Checking geometry...

    Overall domain bounding box (0 0 0) (0.069 0.004 0.003)

    Mesh (non-empty, non-wedge) directions (1 1 0)

    Mesh (non-empty) directions (1 1 0)

    All edges aligned with or perpendicular to non-empty directions.

    Boundary openness (-5.347430223e-18 -1.447816733e-16 -9.586797705e-16) OK.

    Max cell openness = 1.983242651e-16 OK.

    Max aspect ratio = 3.171630836 OK.

    Minimum face area = 3.888093411e-09. Maximum face area = 5.2674561e-07.  Face area magnitudes OK.

    Min volume = 1.166428023e-11. Max volume = 5.832140299e-11.  Total volume = 8.28e-07.  Cell volumes OK.

    Mesh non-orthogonality Max: 0 average: 0

    Non-orthogonality check OK.

    Face pyramids OK.

    Max skewness = 0.0002143106966 OK.

    Coupled point location match (average 0) OK.

I believe openness is only a concern when doing CAD import. CAD geometries tend to be not perfect and can lead to unwanted gaps in your geometry/mesh on import. The values in your log file are good (close to zero).

Hi Anton
thanks so much.so don't need to worry about them.:D
I read somewhere as I remember vaguely that aspect ratio should be lower than 5(?) for better stability and accuracy as I remember,is it true?:)

Lower is better, but there is no fixed rule. In some applications you cannot avoid high values, and still get reasonable results.

Recommended reading: http://www.sharcnet.ca/Software/Flue...ug/node167.htm