Help to fill a 3D object (.step imported file)

[amarilisppt]

Hi to all.
I got this step file I imported into freeCad. How to fill this bended pipe to have the same 3D-shape as if the fluid circulating inside was "frozen"/solid?
Thanks in advance for your advices.
Best regards

[openBrain]

If you run Part/Check_Geometry on the part, you'll see it returns a lot of errors. So most probably it will be very hard to deal with this object.

[Syres]

Well, I got something for you to check, it may not be geometrically correct but I'm guessing you're going to use it for Cfd and so it'll end up being a mesh of triangles in the end anyway.

OS: Windows 7 Version 6.1 (Build 7601: SP 1)
Word size of FreeCAD: 64-bit
Version: 0.20.26858 (Git)
Build type: Release
Branch: master
Hash: e209bc706d35121098f9bac779bc6b09c24ddd95
Python version: 3.8.6+
Qt version: 5.15.2
Coin version: 4.0.1
OCC version: 7.5.3
Locale: English/United Kingdom (en_GB)

Edit: If 'Solid' doesn't show correctly then you will need to install the Curves workbench from the AddonManager.

[amarilisppt]

Thanks!
Yes, you are right: for CFD and meshing in other softwares at the end. Freecad is used to improve existing CAO to forward to CFD tools.

Thanks for your solution; there is indeed an issue with your file, but I will install the addin you mentionned. Anyway, already now,the result seems to be here as the pipe seems to be fiiled. How did you do, please?
Swwep through a fitted curve that foloow the helical shape?
Thanks.

[Syres]

How did you do, please?
Swwep through a fitted curve that foloow the helical shape?
Thanks.

Err no, I'm sure there's many different ways but purely from memory:

Delete the Compound to leave the two Solids
Select each Solid and use Draft>Downgrade which then gives every Face
Delete all faces except those for the inner wall
Select all faces and use Draft>Upgrade
Using the Surface Wb, Fill the two end faces
Select all and use Draft>Upgrade to get the Fusion
In Curves Wb with Fusion selected click the Make Parametric Solid

[amarilisppt]

OK; thanks a lot gaian: I will try!

[heda]

interesting model.

if you intend to mesh this you will get artefacts of the differences in diameter that is in the model,
possibly one could rebuild the surfaces that do have different diameter and get away with it that way.

Snip macro screenshot-083bb7.png (12.64 KiB) Viewed 887 times

out of curiosity rather than going the downgrade route and stitching surfaces,
one can explore what possibilities there are to remodel this.

it turns out that it is not that much effort to do actually.
in this case there is a clear helix and when taking info on all the bends they showed a radius,
meaning that the underlying geometry was arcs.

so using Part_ElementCopy one get a outer seam, after a Draft_Upgrade that one is just to alter the radius of (with the pipe radius) and voilá, one has the actual centerline of the pipe.
the straight pieces is just to do draft/lines on.
to build the Part_Helix, some measurements were taken and then position it correct in space.

at last one can go through the center path with draft/move to make sure that all parts are connected.
when doing that it ranged from 100ths of mm to 10ths of mm's in deltas.
so if one is ok with a remodelling with a few 10th's mm deviation this works just fine.

at the end it is just to make a wire and a sweep out of that.

unfortunately that sweep does not cope with the transition to the helix, it overlaps.
that overlap is probably the failure in the geometry check.
maybe someone is able to say why, to me it looks like occt simply is not up for the job on that.
maybe there are workaround, like sweeping parts and cutting - have not gone down that route.

Snip macro screenshot-75b4a7.png (36.46 KiB) Viewed 887 times

if I would go for meshing I would probably leave it where it is and patch the mesh instead.
the overlap that is in the model is easy to spot and should give a decent shell mesh after
a bit of node-picking.



another thing one can notice is that the sweep can get devilishly sluggish as well.
in a newly opened model it can behave like usual in responsiveness when selecting the sweep in the treeview.
on the other hand it can also take so long that one starts doing something else (fc ui is non-responsive).

have not nailed down why, apart from that helix-sweeps are known to be slow, but there clearly is something that can change over time with an open file - wonder what... (or it was my ancient laptop that was on slow-mode, but why would it be by just open/close fc...)