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Default units in Salome (Meca/Saturne)

  • Alex
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14 years 8 months ago #3524 by Alex
Hi Forum

When working with Salome as a pre-processor, either for Aster, for Saturne or for OpenFOAM, whar are the default physical dimensions of Salome ( or Salome-Meca )...? My intuition says it is mm ( strange choice, most solvers use a coherent system of units, most engineering community adheres to SI... ) am I right...? if it is mm for linear dimension, what is the default unit for pressure, is it N/mm^2 or MPa... or is it other unit like kgf/mm^2... or whatever...?

BRGDS

Alex
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14 years 8 months ago #3526 by kwou
Hoi Alex

the units of Salome and Code Aster are whatever you choose them to be. You, the user, only need to be sure that they are consistent. A nice overview of consistent units are here:
www.caelinux.org/wiki/downloads/docs/PCa...00180000000000000000

So, whether you dimensions are in mm, inch, lightyears, Angstroem, it is all possible as long as your load, pressure, stiffness, temperature, time, frequency, etc are in the same derived units.

kind regards - kees

Interest: structural mechanics, solar energy (picture at 'my location' shows too little pv panels)

--
kind regards - kees
  • Alex
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14 years 8 months ago #3533 by Alex
Hi Kees

Thanks for your reply, I only asked because most of the commercial CAD packages default to some default unit, ProEngineer, SolidWorks, Autodesk Inventor, etc.

Which poses a problem, ( this is why i made this post in the first place ) :

If I import something that i built in a commercial package ( This happened with Autodesk Inventor ) to be part of an assembly or be meshed inside Salome ( Meca ), the default sizes are multiplied by a factor of 1000. The Salome version I am talking about is 3.2.9 i think... didn't try with other versions, because I no longer need to import stuff... I build/mesh most of my designs in Salome...

Seems to me like salome "presumes" that my default unit in the stl file was m, ( whict in fact it was ) and assumed the unit of mm without performing a conversion ... I bit weird i may say... :-(

Didn't this ever happen to you or anybody in this forum...?

I was meshing a T-Junction to be analyzed in OpenFOAM... Obviously that the velocity/pressure fields resulting from the icoFoam ( incompressible viscous laminar flow solver from OpenFOAM ) run were way off from physical reality... :-)

This was about two years ago... never reproduced this quirk again, but since I plan to use Salome in serious engineering design work, I must know how it works... :-)

Alex

BRGDS

Alex<br /><br />Post edited by: Alex, at: 2009/10/14 17:33
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