Learning Forum

[Dato]

Hello everyone,

1、I want to simulate external fluid flow but I fail to have the external flow geometry in DM. Because there are some solid bodies are tangential to each other at many points so I cannot successfully have boolean operation done in DM which will have error showing "resulting in non-manifold geometry".

2、Recently，I learnt that we can enclosure fluid region when imported CAD is only solid region. But I found it seems that it can only enclose for internal fluid region but not for external fluid region. 

3、So here is my question: I want to make boolean operation for this kind of tangential geometry in Fluent Meshign to have my external fluid flow region like we used to do in  CAD phase. Is it feasible 

 

[NickFL]

Import the bodies into fluent meshing. The create a "tunnel" around said bodies. Create a material point at a point inside the tunnel but outside the bodies. Then mesh go thru the mesh controls, etc. The external flow workflow will be a good guide of the steps you need.

[Dato]

Hello professor,

Your advices are highly appreciated. I'm a fresher to fluent meshing. Do you mean enclosure the external flow regions in "outline view" and mesh in "work flow"?   

Is it achievable to enclose computational region in "outline view" and mesh in "workflow"?

[NickFL]

Not a professor here, just someone trying to help people use the software.

As a new user, I would recommend the Workflow approach and Fault-tolerant Meshing. Under the "Describe Geometry and Flow", you can select "External flow around object" which will then allow you to specify the bounds of your tunnel/enclosure. The workflow guides the user through the steps needed to generate the mesh. With the Outline View approach, the user has to remember what has/hasn't been done but it gives the user a bit more control over the process. In theory you could use a bit of both, but as a new user the Workflow approach is recommended.

Keep in mind you still may obtain element with a bad quality near where these two faces come together. One such example is a tire on the road. Depending on where these bad quality elements are in your domain, you may want to refine the mesh in this area. But if these elements are in a non-critical area, then you can simply remove them from the simulation in the Fluent solver. There is a good video on YouTube showing this called "Marking bad elements in Fluent and deleting them from the simulation" from the ANSYS channel partner SimuTech. 

[Dato]

Clearly explain this issue. I understand it and sincerely express my gratitude for your kindly help! It's really a good guide for a fresher.