A material device is not adequately defined relative to the neighboring fluid parts. Urban enviroment model

[luzpdv]

Good morning everybody, I am having problems with the model I am working on. It is a model made with rhinoceros on a specific urban environment, specifically a university campus. The main idea was to make a wind tunnel simulation in a model without trees, only with the buildings that make up the campus. Once this was successfully done, the idea was to add trees to the same model and run the simulation again to compare results, creating different scenarios.
When adding the trees to the simulation, everything works correctly until the simulation starts running and after 5 minutes I get this message. "A material device is not adequately defined relative to the neighboring fluid parts".
Each element in the simulation has its own material, in this case the trees, have assigned certain resistances.
When assigning this type of material (resistance) I have not applied it individually to each tree one by one but I have created a series of rules, I have selected all the trees of a type, I have applied a resistance and I have selected the normal surface to the flow in a tree and it has been applied to the rest. I don't know if this is the problem and I should apply the resistance one by one, which seems crazy to me since there are so many trees. I try in another model that I have smaller, there are only 3 trees and everything works correctly following the same steps explained.
If someone could help me, it would be of great help.
Thank you so much in advance

[marwan_azzam]

Hello @luzpdv ,

You might find your answer in this article:

"A material device is not adequately defined relative to the neighboring fluid parts" - Resistance M...

Marwan

[luzpdv]

I've alredy look at all that articles but nothing... any relation with urban planing or other models that requiere the same as mine. Most of them talk about electronics parts, usually easier to find a solution bc its just one part that causes trouble, I have lots of volumens that can cause the problem 😞
Also my model meet all the requirements the article mentions, thats why I dont know where the problem is
Thank you so much for your response anyways!!

[marwan_azzam]

Hello,

In that case perhaps you want to share your model with us so we can take a look.

Marwan

[luzpdv]

Sure!! I can not attach it because the file exceeds the maximum file size, so I share a link to the zip file with the simulation files. Thank you so much!

https://drive.google.com/drive/folders/13geGeA874qs2CyqgR0OVX2_X3mn7BHNx?usp=sharing

[marwan_azzam · Accepted solution]

Hello @luzpdv ,

The problem is your CAD model. It has interference.

If you suppress the following 6 volumes the analysis will run:

412, 413, 414 and 699, 700, 701.

You cannot have touching resistance materials.

Either suppress those 2x2 trees and their interference or trim the trees in the CAD model so they're separated.

Cheers,

Marwan.

[luzpdv]

wow! thank you sooo much! you just save my life. I was about to give up, I am new in cfd and didnt know a thing about resistance materials, now I know that they can not touch between each other.. THANK YOU! 🙂 

[marwan_azzam]

You're most welcome. I'm glad I was able to help.

Marwan