Units of the files exported from Salome Preprocessor

[annier]

Hi,
A. For Salome Versions V2, V3,V4
This is the thing which i find worth taking care of considering the topic of dimensions/units while exporting Salome Geometry and Mesh into Elmer .

• -> Earlier versions of Salome (those earlier than V5) use the "mm" unit but do not retain unit in exported files (.unv files). i guess it only exports numbers.

• -> I guess Elmer uses SI units.

Let me give the illustrations.
Method 1

• When we need to simulate a cube of 1 m *1 m* 1m.

• We can draw a cube 1*1*1 in Salome (it is in mm there) and export it into Elmer.

• Elmer reads it as (1 m * 1 m* 1m).

• We are using the property of Salome that it does not retain the unit in the exported geometry and mesh.

Method 2

• When we need to simulate a cube of 1 mm*1 mm* 1 mm

• We can draw a cube 1*1*1 in Salome (it is in mm there) and export it into Elmer.

• Elmer will read it as (1 m * 1 m* 1m) if coordinate scaling is not done.

• In the simulation section of Solver Input File (SIF) of Elmer, we add

  Code: Select all

  Coordinate Scaling = 0.001

  and the cube is read as 0.001 m* 0.001 m *0.001 m by Elmer Solver.

B. For Salome Versions V5.1.3 and Later Versions
This is the thing which i find worth taking care of considering the topic of dimensions/units while exporting Salome Geometry and Mesh into Elmer .

• -> Later versions of Salome (those later than V5) use the "m" SI unit but do not retain unit in exported files (.unv files). i guess it only exports numbers.

• -> I guess Elmer uses SI units.

Let me give the illustrations.
Method 1

• When we need to simulate a cube of 1 m *1 m* 1m.

• We can draw a cube 1*1*1 in Salome (it is in m there) and export it into Elmer.

• Elmer reads it as (1 m * 1 m* 1m).

• We are using the property of Salome that it does not retain the unit in the exported geometry and mesh.

Method 2-a

• When we need to simulate a cube of 1 mm*1 mm* 1 mm

• We can draw a cube 1*1*1 in Salome (it is in m there) and export it into Elmer.

• Elmer will read it as (1 m * 1 m* 1m) if coordinate scaling is not done.

• In the simulation section of Solver Input File (SIF) of Elmer, we add

  Code: Select all

  Coordinate Scaling = 0.001

  and the cube is read as 0.001 m* 0.001 m *0.001 m by Elmer Solver.

Method 2-b

• When we need to simulate a cube of 1 mm*1 mm* 1 mm

• We can draw a cube 0.001*0.001*0.001 in Salome (it is in m there) and export it into Elmer.

• Elmer will read it as (0.001 m *0.001 m* 0.001m).

Note:

• 1. If we are constructing the geometry within Salome, it can be quite practical when we assume that Salome just uses the length values and not the units . the consideration of units will be helpful to us for the context when we construct/draw geometry outside Salome i.e. in another CAD software and import it by Salome.

• 2. I am not sure about what units do Salome versions V5.1.1 and V5.1.2 use (I herein assume that they also use SI units).