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Free Hydro/Aero-Dynamic Software Simulators?
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."
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.
"A language that doesn't affect the way you think about programming, is not worth knowing" - Alan Perlis
"Every second geek dreams "
shouldn't that be "Every second geekS dream"
...slashdot sigs are getting so incredibly easy to make fun of, I'm not even going to bother with this one...
Just "borrow" a copy of some CAD software from a college student. :)
Repeal the DMCA!
There's a reason big important navy folk still keep test tanks around... maybe you should invest in one a them heat-carving plastics knives and some good calipers?
Kind of reminds me of those exploding model ships, except not quite.
Keep your packets off my GNU/Girlfriend!
Check out http://www.icemcfd.com/cfd/CFD_codes.html - I maintain a list of CFD codes (free and otherwise) that people send me. It's not really comprehensive but should provide some starting points.
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!
I am a non-practicing aero engineer; I used to do computer simulations on big, big iron. What you're proposing is very, very hard, and quite useless. Instead of trying to re-invent the wheel, look to buy some pre-made blueprints or a plane kit (a diagram of a WWII fighter may be quite fun to build). A vintage prop-plane might even be a better idea --you will certainly learn a lot just figuring it out.
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).
...of owning aero/hydrodynamic fluid simulation software. I mean, what could make u cooler than having large scale simulations (and thus the hardware to run them).
Sipping on Jolt and Dew. Laid back. With my mind of my cubicle and my cubicle on my mind.
Though it isn't quite free (About $80 USD at the moment), X-Plane does a fantastic job at modeling aerodynamics for aircraft, even letting you design your own aircraft and test them. It is primarily maintained by one person, however Piper Aircraft finds it so useful that they have models on their site that you can "fly" in X-Plane and the Carter Copter was designed and tested using X-Plane.
There's a lot more, but this should give you an idea. Use google to find more (this 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!
Acts@core.mailboks.com Acrux@core.mailboks.com Adam@core.mailboks.com Adar@core.mailboks.com Ada@core.mailboks.com
I have the problem of bouncing between simulations that I want to do. Currently I want to simulate some alternative automobile radiator designs - thermodyamic, hydrodynamic, and aerodynamic.
Any suggestions of where to start other than a pile of textbooks and a couple years of time?
However, the right way to do it would be to simulate it with aero/hydrodynamic fluid simulation software first
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 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.
I live in the SF bay area but it's pretty much the same everywhere in the US.
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.
accuracy
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.
"I'll have a Guinness, no wait, make that a Coors Light" -Grad student I work with, who shall remain anonymous...
Just out of curiosity, suppose you wanted to write your own flight simulator (nothing fancy) how would you go about making a mathematical model of the plane? What sort of things to you need to take into account, what do you model and how do you do it? Are there any good books on the subject or web resources etc.?
Stick Men
CADD (two D's I normally don't care about spelling, but when it is an acronym...) is computer aided drafting and design.
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.
"I'll have a Guinness, no wait, make that a Coors Light" -Grad student I work with, who shall remain anonymous...
What you are talking about is a highly couple problem containing many elements that are difficult by themselves today. I am afraid that anything decent would take more than a couple years with text books (unless you are already well versed in computational science), think Ph.D. thesis.
"I'll have a Guinness, no wait, make that a Coors Light" -Grad student I work with, who shall remain anonymous...
You'd probably be interested in Amrita, 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
watch this
It's actually building the model (using some kind of CAD package like Pro/E or Catia) and then creating the computational grid. That may not use up the most CPU time but it definitely takes most of the human time. I don't know of any good free grid generators. (Disclaimer - I work for a grid generation company.)
the server looks fux0red. any idea how to get the source for the most current version ?
X-Plane has a free demo, which comes with a flight simulator that applies Blade Element Analysis on the whole aircraft for realistic flight behaviour, an aircraft maker, a collection of 40 or so airplanes (real and fantasy ones), many more available on the 'Net, a colelction of basic airfoil profiles and an airfoil maker, geographical data for the whole world and an exhaustive list of the world's airports.