Hollow Cylinder One Voxel Thin

[LightBrand]

Hi all, so I've looked through https://github.com/firetools/blenderfds/wiki/Geometries hoping to figure out how to create a thin cylindrical tube , or better yet a thin hollow cone, like a funnel.  It can be one cell thick, or even one plane thick.

Blenderfds helped immensely for creating a solid circle shape (figured out from a blenderfds youtube comment that you have to use cylinder tool with a near 0 Z, instead of circle tool.)  Although up to now I had a spreadsheet that used formula to achieve the same result in building a circle cell by cell.

However now if I need just a thin ring instead of a solid pie, (and by extending the ring along  Z vertex you get a hollow tube) what is the proper procedure in Blender that'll help the fds code transcription process?  Because using Blender you can transform all kinds of weird shapes and curves but they won't be able to transcribe into fds model.  Do you still use voxel to build or do you use edges?  I tried both but the result is too thick.

The shape I need is a hollow cone that ends with a square top instead of a tip.  I can create the shape in Blender but it can't transcribe into fds well.

[LightBrand]

I tried to attach the blender file with the shape but the message won't go through but it looks like this

[Emanuele Gissi]

Sorry for the late reply, your message was strangely sent to the spam folder...

See this example on how to do what you requested:

https://drive.google.com/file/d/1NHdyG-b870LKclOKOHh8-tQ9OehEL3jl/view?usp=sharing

Your thin shape should be a solid, so a minimum thickness is required. Otherwise the voxelization algorithm cannot select solid volumes.

Best,

Emanuele

--
You received this message because you are subscribed to the Google Groups "BlenderFDS discussion" group.
To unsubscribe from this group and stop receiving emails from it, send an email to blenderfds+...@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/blenderfds/e0891e51-46eb-4704-b3fb-9ff40970f2bbn%40googlegroups.com.

[LightBrand]

Thanks emanuel, I did a bunch of testing and seems to arrived at the same result. 

So I saw you used Solidify to increase the thickness then fill as well.  So without it, the shape in Blender will be 1 plane thin, then the voxelization algorithm seems to like to turn the entire shape into a solid.  That seems to be the case for your shape as well if I turn off Solidify modifier.
If I conceptualized that correctly then for my next question of optimization is:

Is there a sure-fire way to select the "proper" thickness in Blender so that the resulting voxel will be one cell thick within my domain (aka as thin as possible), depending on my domain resolution of course.
So to keep it simple, if my domain cell grid in fds is .1m*.1m*.1m.  Then setting the thickness to .1m would realize that right?  Similarly if my domain is .5*.5*.5 then my thickness should be .5m?   If there's no relation then is it a fiddling thing?  Just have to keep exporting and check?
How about that "Custom Voxel/Pixel Size checkbox where you can also define 0.1m (or left unchecked).  What's that option's relation in conjunction with thickness I feel like these two seem to need to be the same number.

Thanks,
Richard

[Emanuele Gissi]

Richard,

the voxelization algorithm tries to understand where the solid is. This is why when the surface is open it fills it.

To my knowledge there is no "sure-fire" way to obtain an 1-cell-thick transformation, except trial and error...

The "Custom Voxel/Pixel Size checkbox" specifies the voxel size for that Object, if you do not want it to have the default Scene value.

If you find a programmatical sure-fire way, I would be very glad to implement it.

Best,

Emanuele

To view this discussion on the web visit https://groups.google.com/d/msgid/blenderfds/b093f1fc-e221-41f1-9d89-5670bf504586n%40googlegroups.com.