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-   -   Dimensionsproblems SLT-file and blockMesh (http://www.cfd-online.com/Forums/openfoam-bugs/70249-dimensionsproblems-slt-file-blockmesh.html)

suitup November 18, 2009 09:02

Dimensionsproblems SLT-file and blockMesh
 
Hi, I'm a little bit confused about this problem:
When I import a SLT-file (for example created by ProE) into paraView and additionally a blockMesh. The dimension of the STL-file is significantly greater than the blockMesh.

The size of the CAD-solid is about 40x40x40mm in ProE, the blockMesh is defined as about (0.1 0.4 0.6) and so on but converted in meter 1.

So actually it the slt-solid should be fit into the blockMesh-box but it doesnt.

To get the solid into the box I ve to increase the boxsize extrem:
Code:

convertToMeters 1;

vertices       
(
    (-50 0  -40)
    ( 50 0  -40)
    ( 50  40  -40)
    (-50  40  -40)
    (-50 0  40)
    ( 50 0  40)
    ( 50  40  40)
    (-50  40  40)
);

That about 50m!

Same problem occurse if i create with snappyhexmesh the new mesh of blockmesh and the stl-file.

I ve no clue.

niklas November 18, 2009 09:16

millimeters?

I dont know what ProE does, but I use ANSA to deal with STL's and the default setting in ANSA is to use mm instead of meters.

So you can either make sure you export the stl in meters, or create your 50 m blockMesh and once
you are happy with your mesh, you do a

transformPoints -scale '(0.001 0.001 0.001)'

to transform it from mm to m.

suitup November 18, 2009 10:41

thank you niklas for the transform-command, I'm going to analyse further the ProE-problem.

olesen November 19, 2009 04:00

Quote:

Originally Posted by suitup (Post 236765)
thank you niklas for the transform-command, I'm going to analyse further the ProE-problem.

Millimeters are standard for many CAD systems (Pro-E, catia, UG, etc.) and your STL is very likely in these units.

There are a number of surface mesh utilities with OpenFOAM.

You can use 'surfaceCheck' to check your STL file and it also outputs the bounding box (in meters).

If you find that it is in millimeters, you can rescale it to meters with 'surfaceConvert -scale 0.001'. If you also need to move your surface about, the 'surfaceMeshConvert' utility allows rescaling (on input or output) as well as coordinate system transformations.


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