SimScale CAE Forum

MRF vs AMI rotational zone


yea i am refering to it, when i run an internal mesh with my model, the mesh cannot complete, is it because I still dont have a closed volume design for my model yet?


Here is the geometry I used:

  • The Box (Pipe) is closed volume.
  • MRF volume is bigger then Pipe (it means it can by bigger, but does not need to be bigger).
  • Top and Bottom, can be defined as Velocity inlet / Pressure outlet.

I suggest you ask for more time, alas: you are near to break and you stop to think. I can help but I will not finish that project for you… :mage:


so sir, my close volume cannot be parts that were assembled together? it must be only 1 part? or as long as it is a closed volume then it should be fine



as you see, my design now is made up of upper plate, bottom plate, lower guide vane upper guide vane and etc, can it be like that?


Dear @100067610,

Please gently explain to your teacher who did not touch the CFD in the past the following:

  • You are getting some results, but you are still learning and problem is much more complex that you expected.
  • You got some help from SimScale community and possibly, with those hints, in one month it will bring expected results.
  • You need some rest, as without sleep only robots can work and you are not perfect robot yet.

VAT (vertical axis turbine) are already not easy stuff to simulate. HAT are really nasty to study: count the cases in the public projects…


Yea , currently I run my simulation with external mesh, and I dont think it is correct because with the duct, it should be an internal flow already. So I think I should run the simulation with internal mesh. But I dont know how to run an internal mesh. According to you , i only need three solid , my blades, MRF , and the guide vane which is the closed volume. Am I right? I am going to change my model later and try out. Lastly, for the refinement, we only need surface refinement for the MRF right?
@Retsam correct me if I am wrong.




I will try it out later and let you know if I success. I hope it ends my pain.


@Retsam for internal mesh, the BMB will only appear after the mesh is finished?

  1. Will you say that using external mesh to simulate a duct design is wrong?


Well, there is not BMB for internal mesh. This is one of the reason I said you need more time, you have to learn more CFD concepts.

External mesh can be used for duct design, but I would avoid it.


But you have a BMB in the example that you created. You added it yourself? And material points


No BMB is used (it would be meshed, possibly an left over definition)


Ok, I guess that is enough for me to try out the internal mesh , wish me good luck. Thank you sir, for helping me so much. I will cite you in my project. You deserve it @Retsam



This is the model for internal mesh, does it look fine? :slight_smile:


@Retsam It does not need to have a hole at inlet right? The closed volume does not need to be hollow too right?


@HamzaBaig did answer again about what I said in that topic, few hours ago. You did not study my simple example, so you ask questions you should not ask. It goes hectic.

As future engineer, you should use resources with care. Those resources are:

  • Time (yours and our)
  • Matter (less is better)
  • Energy (again, less is better)

If you waste resources, you will not become a good engineer. Please pace yourself, do not open new topic for the same simulation. Others are also reading the current topic. Read answers and examples twice or trice, if you cannot grasp it at once, please.

Now the answer is: closed volume does not need to be hollow.




Hi @Retsam
I was just answering about the meshing problem @101210334 was facing and i did not find any of your reply in this topic" A multi-region mesh was assigned - this analysis-type requires a single-region mesh "

I did not go through this topic before answering and i now realized that you have answered nearly about the creation of fluid domain.



Not a blame on you! :grinning: You got catched by ‘101…’ student being exhausted by his Savonius project…


Yeah, that happens in student life.:grinning:


you are right @Retsam
better to ask now than never.
that ways simscale are special than other forum.
@101210334 are trying to gain some CFD knowledge and just like others, people are trying to solve his problem. :raised_hands: (appreciated your effect @Retsam)
almost 6 months ago, I was master to make multi-region model :joy: and always asked the silly question in the forum but trying to learn from my mistake and now I was cross that past.
@101210334 and @tedmund both are the same person? :face_with_raised_eyebrow: beacuse both are working on VAT.