Learning Forum

[Phil]

Hi,

I'm having a really hard time generating a mesh for my geometry and hope someone can give me some pointers, or possible solutions and explanations why it's not working.

The geometry in question is a single cooling channel of a rocket nozzle and consists of a 'U' shaped body (blue) called 'liner', the channel (red) itself, and a lid section that covers the channel (yellow) called 'jacket'. (See the attached pictures ) It's quite thin (approx. 2.5mm) but long (approx. 700mm).

I imported the geometry from an Autodesk Inventor file into Discovery to prepared the geometry (repairs, named selections, shared topology, etc.).

 

I want to add prism layers for the fluid-side channel walls. Could the low first layer height setting (6e-5mm) be an issue? 

Any pointers how to tackle the whole meshing process? Which methods, and mesh settings would you use for something like this?

 

I tried using the MultiZone method for the channel body, and the Sweeping method (all 3 bodies  for the liner and jacket body and added edge sizing at several locations. 

But I keep getting errors and warnings saying 'a mesh couldn't be generated with the current meshing options and settings', 'meshing was completed, but some elements don't satisfy the quality criteria, process was aborted', 'elements with certain quality settings could not be assigned meshing data', 'collision detected, prism layers altered accordingly'. 

I also get a NURBS info when I open the meshing program. Could this be the reason for the errors, or does it just increase the meshing time?

 

The weird and confusing thing is, that I was able to get it working a few days ago, but now it seems like the same settings don't work anymore which is really frustrating.

Sorry, if these are stupid/obvious questions. I'm relatively new to this, so I'm thankful for any tips - even if they might seem trivial or basic for you!

 

Regards,

Phil

 

Note: I losely translated the errors into english, so the wording might be slightly different than the real english error/warning messages.

[peteroznewman]

I recommend you create some surfaces to slice up the geometry.  Slice the liner and jacket using two surfaces that are an extension of the sides of the channel.  Slice the liner using a surface that is an extension of the bottom of the channel. Now all the solids are six-sided bodies.

I also recommend you make about 4 planes that are normal to the axis of the channel. Put one at each end of the large radius bend and one at each end of the small radius bend.  Use those to slice all the solids.

Once you use the Share button in SpaceClaim, the mesh should be almost entirely hex elements. Create a named selection of all the faces of the channel so you can create the inflation layers.

[Phil]

Thank you for your reply.

I found issues in the inital CAD geometry Unfortunately I wasn't able to slice the geometry in the way you described it, but I was able to slice it in the center and make use of the symmetry.

I also found a way to only use the swee function while using prism layers at the same time.

Both helped to create a structured mesh. 

Although, I still have some low orthoganality issues at some of the inflation layers.

[Nilay Pedram]

Thanks for sharing the information