[frafole]

Hi everyone,
I'm trying to mesh an airbox with trumpets inside with ansys fluent but I don't know how to do it. When I generate the mesh the program makes a mesh of all the volume of the airbox but I want it to consider only the walls. How can I do it?

[MB72]

Originally Posted by frafole

Hi everyone,
I'm trying to mesh an airbox with trumpets inside with ansys fluent but I don't know how to do it. When I generate the mesh the program makes a mesh of all the volume of the airbox but I want it to consider only the walls. How can I do it?

Hi
1)What kind of software are you currently using for meshing? Are you using the ansys workbench (14-15) workflow?
2)In order to have a good mesh from the 3D step solid file you need to work a lot on a CAD system (I personally use CATIA V5) and to perform a lot of boolean operation to "subtract" the fluid part from the solid part.
In short: You need to design the internal fluid part as "solid" and mesh it, after that it require a lot of surface shapeing to clean the geometry from small parts and useless details.
3)Making something like this for a real job is not a joke. Sometimes is better to evaluate an airbox directly on engine bench (if you want to produce only few pieces for racing or something like this....)

Post some screen shot and let me judge.

Regards

[frafole]

I'm using ansys fluent workbench v 15. Now the problem is that when I try to generate a mesh it takes about 2 hours and then my computer goes on crash, or it ganerates a bad mesh. Do you know a good setting to make it work?
Thank you very much for your attentions.

[MB72]

Originally Posted by frafole

I'm using ansys fluent workbench v 15. Now the problem is that when I try to generate a mesh it takes about 2 hours and then my computer goes on crash, or it ganerates a bad mesh. Do you know a good setting to make it work?
Thank you very much for your attentions.

I understand that you don't have any experience related to the CFD workflow in ansys workbench. That's not a bad thing, but you need patience if you want to get it work.
My advices:
1)With your experience level (if you have the opportunity) is better to approach the CFD with CFX: it provides to you a number of tutorial (please see the workbench helps).
Ansys workbench is not a video-game. I hope that the people who bought this tool for you (Company or University) realize that you need course and support.
2)The geometry, the meshing environment and the post-analysis environment are the same as fluent (within workbench);
3)Try to start with some very basic geometry (a pipe or some tutorial example);
4)keep always the simulation very simple, avoid to use heat exchange and solid body meshing if you don't need them;
5)Use symmetry planes wherever is possible: each symmetry will cut by half the number of cells;
6)Avoid inlet/outlet supersonic-transonic set up when you start a simulation, you can reach them little by little making converge the simulation gradually
7)Forget to start your own project at this knowledge level, it will be only frustrating for you, even if you are a genius. You need to gain also good surface/solid design competence, in order to "clean" the geometry provided from your customer.
9)Let me check if I have some document for make you starting. I will try to send through private post service of this site. Be patient. It will take a couple of days...

Regards

[sircorp]

Change Mesh from Medium to course. It will reduce the time enormously.

Else if your geometry is circular, Slice the Geometry into sections and use the section only.

Creating meshing requires enormous calculations. Only way to save time is make geometry simple, keep mesh course and any change keep it slow