Free Hydro/Aero-Dynamic Software Simulators? 36
CottonCandyEater asks: "Every second geek dreams of owning a little plane or a yacht/sailing boat, but only few have the money to buy one. The web is full of links on how to build your plane or boat yourself. However, the right way to do it would be to simulate it with aero/hydrodynamic fluid simulation software first, in order to get performance estimates and to optimize the shape. Is there any such software available for free? maybe out of the academic world? I don't mind if it has a front-end or not, as long as it is free."
Do you have the hardware? (Score:3, Informative)
These are actually the kinds of questions big iron is made for. In the end, it's not about how many MIPS, but how many terabytes.
Re:Do you have the hardware? (Score:1)
Re:Do you have the hardware? (Score:2)
In terms of scientific computing, the data set that is the linux kernel is tiny. One gig means you can probably compile it without swapping. But try to do the same amount of processing on a two terrabyte data set and your computer will slow to a crawl. In fact, there are computations that could be done better by an old Vaxen, simply because of its ability to move huge datasets quickly.
Re:Umm... (Score:1)
Hey, it's possible...
A few problems (Score:2)
Does that sound like analysis software to you? All that would give him is a shape, What he needs is CFD (computational fluid dynamics) software.
models? (Score:1)
Kind of reminds me of those exploding model ships [slashdot.org], except not quite.
Here's a list (Score:5, Informative)
There isn't that much out there that's free, though - in the engineering community the people who need to run simulations usually have plenty of money and pay for support, and the people who don't have money (i.e. universities) either get free copies from the commercial vendors or write their own codes (still an interesting project for a student, I guess)
If anybody has entries that should be on the CFD codes list but aren't, please send them to me. Thanks!
CFD (Computational Fluid Dynamics) guy speaks (Score:4, Informative)
I work for a large jet engine manufacturer, in our CFD group, as a developer/expert user/aerodynamicist. One thing that has helped keep my job from going to India like most of our other software positions, is the oppression of the US gov. Export controls greatly limit what is aloud to go into the public domain or over seas. For CFD no 3-D viscous flow solver validatited against real word data (perhaps only military data for non-engine situation, can someone help me out on that one) is aloud out. That means that whatever you decide to use has at best been used to reproduce laboratory situation, not real aircraft situations. That means you will have to use either euler (inviscid) codes that have no boundary layer prediction capability, or marginally validated Navier-Stokes (viscous) codes that will probably get you boundary layers totally wrong (even the validated ones screw up a lot). These boundary layers are extremely important, you can get pretty close for lift and drag predictions with fubar boundary layers, but your stall characteristics will be WAY off. You don't want to fuck that up.
Then the next issue, resources...
You could probably use an euler code on your home machine, or a 2-D NS code, but you could very easily use standard airfoils (NACA) and have experiments (lots of them) to tell you what you would get better than the CFD anyway. The harder stuff (wing body junctions, wing tips...) would still be really hard to do on personal resources even if you could get a good 3-D NS code. For my calculations I routinely use 140+ CPU Days with over a gig of ram per CPU and 1+Ghz CPUs.
In short, good luck, you'll need it.
Re:CFD (Computational Fluid Dynamics) guy speaks (Score:2)
Re:CFD (Computational Fluid Dynamics) guy speaks (Score:2)
Re:CFD (Computational Fluid Dynamics) guy speaks (Score:2)
I'm confused.
Re:CFD (Computational Fluid Dynamics) guy speaks (Score:2)
Don't do this. (Score:4, Informative)
Now, if you really want to come up with a new plane design of your own (which I will be surprised if it hasn't been thought off already), then do what people did pre-CFD: Get a good design book (the Airplane Design series by Roskam is excellent) to understand how airplane design works and rely for your aerodynamics on some well-tested airfoil sections (the NACA series will be more than adequate for anything you can afford to build on your own, even if it has a small jet engine).
And every other geek dreams... (Score:1)
You did ask free... however... (Score:5, Informative)
Re:You did ask free... however... (Score:2)
X-Plane uses finite blade element analysis to model the plane's aerodynamics real time. MS Flight sim uses a table driven model.
So what does that buy you? Flexibility. You can design a new plane and the flight characteristics will be modelled from the shape of the plane. There are literally hundreds of parameters on the plane to set, and you design the shape of the plane with 3D modelling tools.
On the other hand Microsoft flight sim requires a programmer to sit down with his new airplane and a book describing the flight parameters. He flies the plane at top speed, and compares it to the number he sees in a book. If it's off, he twiddles the numbers in a table to get the simulation to match the book. Obviously, if you don't have access to the internals of the program or if you're designing a new plane that doesn't exist in real life you're out of luck.
A few resources... (Score:4, Informative)
There's a lot more, but this should give you an idea. Use google to find more (this [google.com] may be a good place to start :-)
Aerodynamics is a huge field, and i doubt you'll ever get far enough to build your own plane, but if you're anything like me you'll have a lot of fun trying.
Good luck!
Or other physics simulators? (Score:2)
Any suggestions of where to start other than a pile of textbooks and a couple years of time?
No Good News (Score:2)
The best way. (Score:2)
Hmm, perhaps that is the right way but, there's a lot more to it. Fluid dynamics and boat design is really an art, bordering on alchemy. Sure heavy duty hardware doing fluid dynamic simulations factors into it but, theres a lot more as well. Also, you need to be such an artist to make it work. Simply having the hardware and software to do such simulations is woefully inadequate.
If you want the best boat design you need to take a cue from the professionals. In this case you probably want to do what Team OneWorld did with their America's Cup boat. Just pilfer [iol.co.za] the plans from other peoples designs. The work's already been done for you so, it saves you from having to do all that expensive testing and prototyping.
Sailboats aren't expensive... (Score:2)
A 22ft sailboat with outboard and ready to sail costs less the $5k. It's not new, it's not the fastest but it can be raced/cruised.
A 35ft sailboat can be had for less than $30k ready to sail.
Slip fees usually run $5-$6 a foot.
I personally like high performance dinghies and they can be had for less than $3k, but you need a wet suit.
Unless you want to have a 60ft steel cruiser it's nearly always cheaper to buy a used sail boat than build one. Like most things boats depreciate with age, unlike most things boats are built to last.
Amrita: Open-source CFD (Score:2)
You'd probably be interested in Amrita [amrita-cfd.org], an adaptive mesh refinement CFD software package that is completely open source. You'd have to contact the creator, James Quirk, for the full details on its use. But it's a fantastic package that can do an incredible amount -- far more than just CFD (you can use it for solids, etc.). The web page is fairly old (it's been in use for over 6 years so the "trials" period is long over).
GMD
Solution isn't the hard part (Score:1)