SnappyHexMesh: non-closed surfaces

Problem

Geometry .stl

Problem

You want this:

Problem

But you get this:

Origin: non-closed .stl file

SurfaceCheck

             >> surfaceCheck foo.stl

Output:

              Surface is not closed  since not all edges connected to two faces:  
                  connected to one face : 228 
                  connected to >2 faces : 2 
             Conflicting face labels:234
             Dumping conflicting face labels to "problemFaces"
             Paste this into the input for surfaceSubset

SurfaceSubset: visualising the problem

Write subset of the triSurface (foo.stl) to separate .stl (problemFaces.stl)

Requirements:

surfaceSubsetDict
reference zone/surface
output of surfaceCheck (problemFaces)

Examples dictionaries can be found here

             >> surfaceSubset SubsetDict foo.stl problemFaces.stl

SurfaceSubset: visualising the problem

             >> paraFoam

Visualisation of .stl in paraView only works when there is already a mesh loaded ?!

SurfaceSubset: visualising the problem

Holes between flat and curved surfaces!

SurfaceSubset: visualising the problem

Holes between flat and curved surfaces!

SurfaceSubset: visualising the problem

The solution

Change triangulation parameters in CAD (Max. edge length, aspect ratio):

tune parameters on smallest surface
use parameters to export all surfaces

The solution

             >> surfaceCheck newFoo.stl

Output:

              Surface is closed  All edges connected to two faces. 
             Number of unconnected parts : 1

Final notes

Note 1: There are multiple ways of achieving a watertight geometry

Several STL repairing tools are available
OpenFOAM utility: surfaceMeshTriangulate
Nevertheless: "Voorkomen is beter dan genezen", "a stitch in time saves nine"

Note 2: In some CAD tools it is not possible to specify triangulation parameters (Salome?) In that case you should mesh each surface with the same segment length and export to .stl