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."

Comments

Do you have the hardware?

[jericho4.0]

There are probably lots of fluid dynamic packages available that would run under Linux and do just what you ask. The problem is that for an acurate model, it needs to be very fine grained. This means lots ( and lots) of memory, lots of storage, and lots of IO.

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.

Here's a list

[wayne606]

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!

Don't do this.

[costas]

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).

You did ask free... however...

[WhiteBandit]

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.

A few resources...

[bob@dB.org]

• XFoil - XFOIL is an interactive program for the design and analysis of subsonic isolated airfoils. It consists of a collection of menu-driven routines which perform various useful functions
• NASG Airfoil Database - This database includes airfoil specification(contour,thickness ratio and etc.) and performance(lift,drag and moment) data widely.
• Aircraft Design Software Review - This page originated from a paper given at the ASEE Annual Conference, Sunday, June 25, 1995, Anaheim, CA (Gary Slater, session chairman: Software and Multimedia). It has been updated for design class use.
• CompuFoil - CompuFoil is the industry standard in airfoil modification and plotting software. Used by SIG, Estes Industries, Midwest Models, Hobbico, House of Balsa, HobbyHangar, Great Planes Models, R&R Products, CR Aircraft, DJAeroTech, The Electric Jet Factory, NASA, West Point, dozens of schools, colleges, universities and discriminating R/C modelers around the world. CompuFoil runs on Windows 95, 98, and ME. It will also run on WindowsXP/2000, and Macintosh computers (with a PC emulator), but these two require a custom setup program stub file..

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!

CFD (Computational Fluid Dynamics) guy speaks

[TamMan2000]

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.