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Registered Member #15
Joined: Thu Feb 02 2006, 01:11PM
Location:
Posts: 3068
Not a mechanical or aeronautical engineer, so need some help on this. Looking for some of the commercial software programs out there that can calculate the center of pressure for either a 2D or even 3D model.
The three i have so far are Rocksim (Apogee), HyperCD, and SpaceCad, although i would consider these to be entry level amateur based programs vs. true commercial packages that can import solid models, etc...
Vigilatny Registered Member #17
Joined: Thu Feb 02 2006, 02:47PM
Location: NL
Posts: 158
What is the application? If it's not that big a deal I would suggest just using something like the vortex lattice method in matlab etc. The math isn't that difficult, I think I did it as a sophomore engineering student.
Otherwise any old CFD/FEM/FEA package can do it, but learning to use those correctly can be nearly as much work as building your own model. My favorite is ANSYS, but it's not known for its cfd prowess. NASTRAN (and derivatives) is probably the standard. A short google search showed fluent to be well known. Anyhow, none of those are remotely cheap.
After looking up the models you mention, I'm guessing model rockets, then the question becomes how big and what shape?
Registered Member #49
Joined: Thu Feb 09 2006, 04:05AM
Location: Bigass Pile of Penguins
Posts: 362
Its hard for me to imagine an amateur project that wouldn't be better off using published data tables. If all you're doing is model rocketry then you should seriously consider seeing what you can do with an aeronautics book and some paper. We could probably help you with any trouble you have. The problem being that when you simulate (especially in 3D, and especially with on small models) you have a stackup of assumptions and "tiny" unmodelled features that will seriously affect your results.
Assuming you're dead set on it and can handle a 2D sim, Ben's got the right idea with something like vortex lattice or a panel code. Both are incredibly simple and abound on the web in applet and downloadable form if you don't want to write your own. You certainly won't find an intuitive code that will suck your model directly out of Pro-E or anything, but it can model simple profiles reasonably well. has a basic set of tools that can make pretty colors too!
If you need the ability to import a whole model, good luck. You can try one of the professional packages but, again parroting Ben, you pretty much can forget about sitting down and "just figuring it out". Plus I wouldn't really trust anything that comes out, especially for low reynolds number cases like I'd imagine your model is.
If you find you absolutely have to have 3d modelling capabilities, you might consider X-Plane. Its a blade-element modeller in a flight simulator, which means its not CFD per se, but a slick wrapper on a large set of lookup tables. That said, it has huge data output utilities and I've been working on an aeronautical project for some time and I find that Xplane produces results even for low reynolds numbers that closely match my experiments....
Registered Member #56
Joined: Thu Feb 09 2006, 05:02AM
Location: Southern Califorina, USA
Posts: 2445
There might be a flight simulator out there that has the ability to import a 3d model, and calculate the Cp for you, but I have my doubts.
If it is something simple that you need to model (like say, a rocket), I have a copy of Rocsim... But I can tell you that it isn't going to give you an exact Cp distance, even with normal rockets the different methods of calculation can range +/-10%
Also, it wouldn't suprise me if SolidWorks or Pro/E does it...
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Commerical software for calculating Center of Pressure
