[Hectux]

Hi,

I am trying now to create my meshes with Salome-Meca.

My problem is: Where can I see the dimmension I am working with?
Is it Meters or Millimeters? Where can I change them?
What happens with the dimension when I convert it into OpenFoam via UNV file?


Thanks a lot.
Best regards

[santos]

Hi,

I think Salome uses SI units, so you get your dimensions in metres by default.

I normally scale my mesh after converting to OpenFOAM format with:

transformPoints -scale '(1e-3 1e-3 1e-3)'

The last argument is the vector you use to scale your points. In this case, it converts your points from m to mm.

Regards,
Jose Santos

[tomislav_maric]

I'm also using Salome to generate CAD geometry for multi component wings, and I'm wondering how does Salome calculate Inertial properties (Inertia tensor). I've asked this on Salome forum but got no answer. If I generate a split airfoil and extrude it in a shell object, it has no thickness. Material properties are also not defined (unlike in other commercial CAD software). Still, Inertia tensor components are generated. Do I calculate real values by multiplying the given ones with real density in kg/m^2 (here I presume that this value is preset to 1 in Salome since I'm unable to find where the material properties are defined.). ANY advice is greatly appreciated.

Tomislav

[Hectux]

Ok. Thanks. I will play a bit with this.

But I also have another question.

At the Moment I am making my geometry with Salome.
Save it as STEP file. Mesh it with Netgen --> Save as NetgenNeutral and convert it via netgenNeutralToFoam.

Works good for my work.

My question is: When I mesh a simple geometry e.g. a pipe (cylinder). Netgen needs only a few seconds for it.
When I try to mesh the same geometry with Salome-Meca, it takes the whole morning and afterwards I run out if memory:
Error in the terminal: "Lack of memory"
Error in Salome: "Memory allocation problem"

As Algorithm I use Netgen 1D-2D-3D.

[paulo]

Hi all,

We've been using Salome for a while, and we have some experiences we can share:

- Salome uses milimeters: Then if you model a 1x1x1m cube, mesh it and export to OF using UNV format (Salome doesn't retain the dimensions info), the cube will be 1000x1000x1000, that OF reads in meters. You'll have to use transformPoints or create it in Salome with 1x1x1mm;

- Salome works well with complex geometries since you use tet meshes. We tried a lot of hex mesh options in a imported geometry (STEP format), but unsuccessful;

- Salome is quite memory eater (maybe because of the GUI). So if your HD starts blinking, stop the process and change the quality settings or wait a whole week. Increasing the RAM is also a good option. You can monitor the processes using CTRL-ESC;

- There is a newer version in the site www.salome-platform.org . We didn't try it yet, but I hope something about the hex meshes is fixed/improved;

Sorry for the bad english.

Regards,

Paulo.

[Annier]

Originally Posted by paulo

Hi all,

We've been using Salome for a while, and we have some experiences we can share:

- Salome uses milimeters: Then if you model a 1x1x1m cube, mesh it and export to OF using UNV format (Salome doesn't retain the dimensions info), the cube will be 1000x1000x1000, that OF reads in meters. You'll have to use transformPoints or create it in Salome with 1x1x1mm;

- Salome works well with complex geometries since you use tet meshes. We tried a lot of hex mesh options in a imported geometry (STEP format), but unsuccessful;

- Salome is quite memory eater (maybe because of the GUI). So if your HD starts blinking, stop the process and change the quality settings or wait a whole week. Increasing the RAM is also a good option. You can monitor the processes using CTRL-ESC;

- There is a newer version in the site www.salome-platform.org . We didn't try it yet, but I hope something about the hex meshes is fixed/improved;

Sorry for the bad english.

Regards,

Paulo.

Thank you for your illustrative explanation.

[Naresh yathuru]

Hi Paul thanks for the information on the dimensions in salome. I just starde using salome 7.5 . just out of curiousity i would like to know how can i change the units in salome from default mm to meters.

[flowAlways]

Hello,
Has any one used the Manage Dimensions utility in the latest version of salome 7.5.1.
documented here
http://docs.salome-platform.org/late...ions_page.html

It works but the GUI does not ... I am not able to drag the dimension around and all the dimensions together look messy. Has anyone tried this utility and able to move(drag) the displayed dimensions ?
Thank you very much!

[nicholas.jones]

Hey Ali,

I am having a similar problem with Salome. I cant seem to move the dimensions!

Did you ever find a solution?

[Tobi]

Dear all,

I will not bring up this thread again but I had the same problem with the moment of inertia calculation (how to interpret this) like Tomislav. However, to help other people (because no one was replying to this question) I will tell you how salome works in that manner. To figure it out is very simple. Just build a full cylinder with 0.5m of radius and a hight of 10m (extrude in z-direction); by the way you can select the units in Files - Properties. Doing so, we can calculate the the which is:



Assuming that the material is an aluminum alloy with the density of 2700 kg/m^3, we can compare both, the analytic solution and the calculation based on Salome. The result is:





If we multiply the Salome calculation by the density, we get the same solution that we get from the analytical one. That means, that Salome uses the default density of 1. It should be possible to set this value using python but please do not ask me how

Hope this help anybody in future.

[Annier]

Hi Tobias,
Thank you for your wonderful illustration and explanation.


Yours Sincerely,
Anil Kunwar