topic Re: How to properly design a model to be used in Autodesk CFD? in Inventor Forum

How to properly design a model to be used in Autodesk CFD?

Anonymous — Fri, 17 Aug 2018 00:01:12 GMT

Hi,

I am designing a rocket body on Inventor and eventually would like to do a CFD/structural analysis. I can design the parts of the rocket properly (basically a giant cylindrical tube and 4 grid fins) but I don't know how to "put" the two designs together properly.

I would like to avoid a mistake I made last year where I created the 4 grid fins first, then created the rocket body to "join" the grid fins together.

That probably isn't the best way to go about this. How would I create a cylindrical tube (represents rocket body) and place 4 grid fins in their respective spots properly?

Also, whenever I ran the same model I described above, I got a bunch of errors with big red arrows pointing at the grid fin. I remember trying to find a solution to this but nothing came up- a part of me is telling me that I designed the grid fins in a way CFD didn't like. I used this tutorial to create the fins.

kelly.young has embedded your image for clarity.

Re: How to properly design a model to be used in Autodesk CFD?

Anonymous — Thu, 16 Aug 2018 23:18:42 GMT

Edit:

Ignore the last paragraph. I think I can figure that out on my own if someone can help me with my first problem.

Re: How to properly design a model to be used in Autodesk CFD?

mcgyvr — Fri, 17 Aug 2018 12:43:24 GMT

Sketch a circle centered on the origin planes... then extrude it..

Create a new sketch on one of the origin planes of a rectangle the same size as the fins and extrude it to create a fin..

Create a circular pattern to create 3 more fins..

Your post is really lacking details (or you assume we know the nuances of your design)

There are multiple ways to model such a shape.. A single picture is hardly sufficient details to show your design intent nor to divulge the reasons your previous attempt seemed to fail to you..

All I will really say is model parts and assembly them just like you would in the real world.. Or as close as possible to real world processes,etc...

Fins are likely to be bolted on through holes,etc... model the holes.. constrain holes in fins to holes in rocket body,etc...

Of course simplification can certainly be something you may do depending on your intents..

Re: How to properly design a model to be used in Autodesk CFD?

Mark.Lancaster — Fri, 17 Aug 2018 12:49:23 GMT

@Anonymous

Unless I missing something here.. But why is your model browser info so long for a simple design? I see numerous delete face functions and etc..

Re: How to properly design a model to be used in Autodesk CFD?

mcgyvr — Fri, 17 Aug 2018 12:53:53 GMT

And I forgot..

Post your actual Inventor files and state the version of Inventor you are using..

Re: How to properly design a model to be used in Autodesk CFD?

Cnoj — Fri, 17 Aug 2018 14:12:53 GMT

Dear 0700526,

Multiple bodies are not necessarily a good idea - Sim CFD will treat each body as a separate part and you may get meshing issues where they meet. If you're just doing external airflow analysis, one body should be fine.

I'm guessing the red arrows you saw were the CFD Mesher telling you the grid fin edges were thinner than the Minimum Refinement Length. When you have a big model with small complex areas you have to take measures in Sim CFD to make the complex bits mesh properly but that's a Sim CFD Forum topic..