[CFD] Pipe Mesh Transitions (Unstructured, Hexcore, Block Structured)
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- Опубликовано: 26 июн 2024
- A collection of methods for meshing the transition from a cylindrical pipe into a larger domain using Beta-CAE Systems ANSA.
Timestamps
0:00 Introduction
1:37 Geometry
3:11 Block Structured Approach
10:22 Alternative Blocking
14:21 Improved Blocking
19:55 Unstructured Approach
26:56 Improved Surface Mesh
30:53 Mixed Structured / Unstructured
35:14 Summary and Outro
#ansa #cfd #meshing
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Disclaimer
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The methods, algorithms, equations, formulae, diagrams and explanations in this talk are for educational and demonstrative purposes only. They should never be used to analyse, design, accredit or validate real scientific / engineering / mathematical structures and flow systems. For such applications, appropriate trained, qualified and accredited (SQEP) engineers / scientists should be consulted along with the appropriate documentation, procedures and engineering standards. Furthermore, the information contained within this talk has not been verified, peer reviewed or checked in any way and is likely to contain several errors. It is therefore not appropriate to use this talk itself (or any of the algorithms, equations, formulae, diagrams and explanations contained within this talk) as an academic or technical reference. The reader should consult the original references and follow the verification and validation processes adopted by your company / institution when carrying out engineering calculations and analyses. Fluid Mechanics 101 and Dr. Aidan Wimshurst are not accountable or liable in any form for the use or misuse of the information contained in this talk beyond the specific educational and demonstrative purposes for which it was intended. 
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Your work and contributions towards the CFD learners, experimented people and newcomers is wondrous. Thanks for everything, Aidan!
Just amazing. This and the previous meshing tutorial is one of the most helpful videos I have watched about the topic. It covers many important details which can help both at beginner and intermediate levels. Thank you for sharing your experience. I am looking forward to seeing your coming videos :)
Thank you for this video! Love seeing concepts from your previous lectures being demonstrated trough meshing.
It is really informative how you explain mesh quality metrics. Just waiting for your upcoming lectures.
yes, I have enjoyed today's video, really great effort.
Thank You for your generous explanation !
Very interesting! I had to cancel so many calculations because of this "big and small" difference and the "hard edges" 🙂
Thank for your work. It's ver useful.
One of the best video of yours! Please more meshing videos!
very useful !
Thank you very much, this happens to be quite useful for my master thesis :)
Great! That's just what I was hoping for
I am in the structured approach but came up with a different alternative actually. I just made the o-grid wider as it was entering the big volume in order to reduce the Aspect ratio, which went from values of even 230 to 10-15 approximately. Do you know by any chance what would be a too high Aspect Ratio for combustions processes in Fluent?
I don't know about combustion specifically but generally aspects ratios of up to 10 are fine in the bulk flow, and anything up to 1000 in the boundary layer also seems to be fine
Thank you very much!
Hello video was very good. We would appreciate if you would do more videos on meshing and the use of automotive components for meshing.
Hello! Dude, I love your videos and the quality of your explanations! But, I'm a CFD beginner, can you recommend me where to start in your videos? I'm a little lost....
Sure thing. I would probably start with my series on residuals (it is a 4 part series), as you will be looking at residuals in all of your simulations! So a good understanding here is very useful (also I use a simple example of heat conduction in a bar, which should be easy to follow).
Then I would probably have a look at the videos on k-epsilon and k-omega SST turbulence models, as most of your simulations will be turbulent. These are two most popular turbulence models, and often you will have to 'choose' one of them. It is good idea to at least have a basic understanding of what they are.
That should enough to get you started. Let's me know if you need any more suggestions
It's amazing, eager to see more videos like this . Could you please use Salome meshing or any other Open-source software as well.
I don't think eveyone has license to these paid softwares.
salome can be automated using python.
Yes, for sure. I wanted to see what the reception was like for these types of videos. If people would find them useful, then I will see what I can do 😃
I just wanted to drop by and express my immense gratitude for the fantastic content you create in the realm of CFD. Your videos have been incredibly helpful in expanding my knowledge and improving my skills in this field.
I do have a question though, and I hope you could shed some light on it. I've noticed that when using Fluent, the mesh metric indicates good mesh quality after surface meshing, but it seems to deteriorate when generating the volume mesh. I'm wondering if this could be due to the inflation layer growth rate?
Your insights on this matter would be greatly appreciated. Thanks again for your dedication to sharing your expertise with the CFD community!
Good question. The best thing I can suggest is to have a look at the layers after you have grown them and see if you can see where they might be having problems (sharp corners, compression into tight spaces, 3D corners). It is usually in these locations where the quality deteriorates.
A useful trick is to grow 1 layer, and then check the quality. If this later is ok, then delete it and try growing 3 layers. Check the quality and then delete them. Now try with 5 layers. And so on until you have all the layers you need. When you are happy, then move onto the volume mesh.
It may be that when you have a high growth ratio your outer layers are getting into trouble in the corners/close to other geometry etc. Hopefully this method of trying a few layers at a time should help you to understand exactly where you are having the problem.
Think like a detective! Can you figure out the puzzle?
@@fluidmechanics101
I want to extend my heartfelt gratitude for your prompt and insightful response. As you suggested, I've started to closely examine the mesh layers after growing them, paying particular attention to areas where problems may be occurring, such as sharp corners, compression into tight spaces, or intricate 3D corners. This method of investigating the mesh layers incrementally, starting with one layer and then gradually adding more while checking the quality, seems like a sensible approach.
One example I've observed is that when examining the quality of the surface mesh, the skewness is within an acceptable range, with a maximum value of 0.6. However, when creating the volume mesh, the skewness increases significantly, with a maximum value of 0.9. This discrepancy has led me to speculate that the problem might be related to the higher growth ratio not being optimized for certain regions.
This was in ANSA, right? How would you compare it to Icem CFD, general ANSYS Mesher, or Pointwise (Cadence), or other. Thanks
I can confidently say that ANSA is my current favourite meshing software. ICEM is very buggy and it can take days and days to create a workable mesh (it took me about 2 months to mesh a wind turbine blade for my PhD...) ANSYS mesher is fine if you have a basic geometry that you want to fill with tetrahedra. But as soon as you try and do something with structured regions and complicated meshing approaches, it quickly becomes infeasible. I haven't used PointWise, so can't comment on that one.
At the end of the day, the best meshing software is the software that you have access to and are confident in using 😊
HI! As always big thanks for knowledge which You sharing. I got one question, is the mixed structured/unstructured method of meshing is available in Ansys Fluent?
HI marek, I am using fluent for meshing and yes actually in fluent they have something called multizone meshing approach, where you can create hexahedral type structured mesh, otherwise with the Hexcore method in watertight geometry, you can create hybrid mesh (triangular surface mesh, hexahedral volume mesh, and tetrahedral transition layer)
By the way this multizone meshing is a relatively new and I personally find not stable, requires great effort.
Agreed. My current preference is definitely ANSA (if you have access to it). It gives you a lot more control, particularly for these complex meshing approaches
i think your audio is messed up? Sounds like an echo or something
Yes, the audio is a bit messed up in places. Sorry guys! After some investigation I think it is because my laptop isn't able to handle ANSA and OBS studio (for screen recording) at the same time. This results in it lagging the audio in places.
I found similar issues with the previous ANSA video and I am going to try and find a workaround for future videos. This is also a good lesson for me that more intense CAD and CFD packages might need a bit more careful preparation, if I try and record detailed videos for you guys.
Hopefully the video content is still understandable? Let me know if you have any thoughts or suggestions, I would really appreciate it
Would you be able to do a tutorial on using Blender for meshing? Thanks.
Yes, in the future I would love to look at some more software applications.
However, I think I need to get the audio fixed, as my laptop doesn't seem to be strong enough to handle CAD and OBS studio simultaneously, without lagging the audio ...