Best OSS CFD Package For High School Physics? 105
RobHart writes "I am teaching a 'physics of flight' unit to grade 11 Physics students. Part of the unit will have the students running tests on several aerofoils in a wind tunnel. I also want to expose them to a Computational Fluid Dynamics package which will allow them to contrast experimental results with those produced by the CFD package. There are a number of open source CFDs available (Windows- or Linux-based are both fine), but I don't have much time to evaluate which are the simplest to use in terms of setting up the mesh, initial conditions, etc. — a very important issue as students do not have much time in this unit." Can anyone offer insight about ease of use for programs in this niche?
Too Complicated (Score:5, Insightful)
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Re:Too Complicated (Score:5, Insightful)
Yep. Neither of them. No place that uses CFD as part of the job is going to accept anyone who isn't a certified engineer with extensive training in its use.
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I'm guessing they're 3rd or 4th year engineering or science undergraduates, though, not kids who would only have encountered CFD in high school.
Learning vs Exposure (Score:5, Informative)
Just because they don't have the mathematical background to fully understand the models, doesn't mean that it is worthless to expose them to the concepts. Playing around with flow simulations and seeing how changes in geometry affect flow is fun, and can give them a feel for the basic concepts of aerodynamics. It will make the class more interesting, and encourage them to pursue physics or engineering as a career.
Re:Learning vs Exposure (Score:4, Interesting)
Playing around with flow simulations and seeing how changes in geometry affect flow is fun
Agreed, but I'm afraid that playing with CFD will just leave the students frustrated and convinced that physics doesn't work because they can't get CFD to work. I remember kids in high school, (even some in college) deciding that physics doesn't work because they couldn't get newton's laws of motion to match the results they observed experimentally. In reality, they didn't do their math correctly.
If the author want's to quickly demonstrate the principles of fluid mechanics to his/her students here is my plan:
1) Make sure they have a firm grasp on Newton's laws of motion.
2) Have them drop a paperclip and a coffee filter from the same height and measure how long it takes them to hit the floor.
3) Explain to them that this is the effect of aerodynamic drag.
I performed the same experiment in college physics. It's quick and effective.
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A college professor earned money by dropping a paperclip and a coffee filter? What kind of class was this, exactly?
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I believe I saw that demonstration in elementary or middle school back in the 1970s or 1980s. In high school, our physics teacher showed a feather falling in a vacuum (much cooler). Get with the '80s already! ;-)
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Unless they're learning something about *how* the model generates the results -- which takes a lot of explaining even if you minimize the formula use -- all they'll get out of it is:
"Magic computer gives magic results that we compare to some experiment."
The most important thing to impart on the students is not any fact itself, but that nature is not magic, that we use models to understand and predict nature, and that you can learn how the models actually work if you try.
Since they won't have the time to lea
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Your right that it may not "teach" them a lot, but if it makes it fun they can realize that science isn't always boring. It just might be the thing that makes these students want to investigate a future in science or computers. Would any of us have ever been interested in computers if we hadnt seen what amazing magical things could be done with them? A few of us maybe, but honestly not very many I think.
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CFD is simple. for every timestep and every volume element, you calculate pressure and air (fluid) movement. If there is a pressure difference speed will increase (or decrease). When moving air can't go further, e.g. because it hits something solid, pressure increases.
In one paragraph I've explained the basics of CFD. This means you can teach it to high school students in an hour.
If they've played with say excel before, you can let them do a one-dimensional CFD in excel. (just pressure and speed.).
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Visuals (Score:2)
For visuals, UIUC's Airfoil Data Site [illinois.edu] is a good place to start.
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That's what they used to say about computers.
But when I was learning to write Fortran in school in 9th grade, grad students were learning to write Fortran at the university across town, and making more mistakes and understanding it less than I was.
I would expect the CFD program that would suit this class is something that takes a simple grid input for the surface, simple initial conditions, then runs the flow and plots streamlines or vectors. No need to get into the theory behind the sim computations, just
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I would expect the CFD program that would suit this class is something that takes a simple grid input for the surface, simple initial conditions, then runs the flow and plots streamlines or vectors.
I don't believe there are "simple initial conditions" for CFD software.
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Of course there are. Uniform initial density, zero (or uniform) initial currents, and a source at one grid point.
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CFD is just too complex for high school students
Oh come on. These students have already learned natural language processing, is that not complex?
Perhaps it's the learning method that counts, not the subject.
Re:Too Complicated (Score:4, Informative)
Sorry, but trying to understand the results of a CFD simulation require a solid understanding of fluid mechanics and an understanding of shear stress, which in turn requires a solid understanding of calculus and differential equations.
Re:Too Complicated (Score:5, Insightful)
Similarly, no one has ever gotten good at baseball without first earning a PhD in ballistics.
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Well, once you teach them calculus and differential and partial differential equations.
You can break them in with the Navier-Stokes [wikipedia.org] equation.
Then break them the news that air foils don't lift because the air on top is "moving faster" but because it has to make minute angular accelerations. Since the air temperature doesn't change, the energy needed for drops out of the pressure. Tada, lift.
Or something like that.
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Then, you apply this to airfoils.
Then, you go to the NASA page and get
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Oh bullshit. PDE's don't require grad level understanding. When I was an undergrad, I hacked up a simple first-order PDE solver (in PHP no less) for an extra credit problem I was doing at community college, and it did the job. It wasn't great, it wasn't robust or accurate or fast, but it was ridiculously easy to do. And I understood it fine. And I would have understood it fine as a high schooler, if I hadn't gotten kicked out of calculus.
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Explaining the Reynolds number might be the most complex part of the class, actually. I mean, they're already doing wind-tunnel simulations to begin with - h
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I don't know where you come from, but we have a stage in between.
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I agree. Not only is CFD complicated, running experiments properly and analyzing experimental results are hard. What I fear is, you will end up asking them to contrast improperly measured results from a poorly run set of experiments against some computer output none of them has any understanding of. But the lesson learned is still going to be valuable, experimental and computational physics are hard.
Entirely irrelevant and wasteful answer. (Score:5, Insightful)
I would imagine that the instructor has already decided that the topic would match the students. If it were a regular level course, then it's likely he'd show a video on the topic and it would be good enough. Instead he's chosen to broach the math involved by attempting to simulate a fluid dynamics scenario.
In short, instead of assisting the teacher in his attempt to try and broaden the minds of ambitious youngsters, it almost appears that you're simply recommending that he stops doing his job, packs up and maybe instead teaches ABCs and 123s.
Let's face it, if he's a teacher who is "qualified" to teach a topic like computational fluid dynamics, I'd imagine that he wasn't hired to teach just the average "who gives a shit" student. There are enough useless teachers who wouldn't bother out there already. This guy at least makes the effort of trying to figure out how he can best accomplish the task of teaching a complex subject.
Please don't EVER!!!! stop an ambitious teacher from attempting to educate ambitious students in the future. Especially not under the premise of suggesting that it shouldn't be done.
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Back in the 1990's, TV programming for schools (UK) used to have programs for A-level physics that covered this topic. The depth of explanation would be simply to have a cross-section of a various shapes (brick, sphere, aerofoil, triangle, flat panel) all in a wind-tunnel or wave-tank. Then smoke or dye would be added to show how much turbulence there was. The goal wasn't to explain fundamentals like curl, divergence, gradient fields, Eigen-vectors or Navier-Stokes equations, just to give an insight into wh
openFOAM (Score:5, Informative)
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Check out openFOAM [openfoam.com]. You might find that it meets your needs
Good answer. The price is certainly right.
The most widely used CFD software is probably StarCD. [cd-adapco.com] Unfortunately, it's probably cost prohibitive for a high school.
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Not really, CD-Adapco was handing out free licenses to students. I had a continuous 4 year license throughout college for StarCD. If you ask them nicely I'm sure they would provide you with a free copy for educational use.
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And when you're working on the equivalent of "hello world" (ie, that specific file is never going to be used again), it doesn't matter.
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What the heck are you talking about?
The results you obtain can easily be exported as a plain text database or put into spreadsheet, considering they are tables with numbers for pressure, velocity, temperature, etc after all... Your 3D modeling data will most likely come in as some sort of open standard anyways. The files aren't nearly as important as the raw data.
I don't see the vendor lock in, care to clue me in?
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That wasn't an actual person you were responding to, it was one of the mindless "commercial software BAAAD" bots that inhabits Slashdot.
Re:openFOAM (Score:4, Informative)
Took some digging but I found a page where they actually show some pictures:
http://www.openfoam.com/docs/user/cavity.php#x5-110002.1.2 [openfoam.com]
You'd think they'd have some color somewhere on the home page, but OSS types rarely have a marketing clue...
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openFOAM is very powerfull, i would say that it's too powerfull for the task
IMHO the minimum requirements to consider even using it are:
-C\C++ knowledge, to be able to write the 'problem statements' you need to be confortable with it.
-Obviously knowledge about fluid mechanics is required: Reynolds/Froude/Mach numbers, Bernoulli equation, steady/unsteady flow. This knowledge is required to be able to pose the problem. You will need a lot of knowledge about PDEs and boundary conditions, and the basics about t
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While OpenFOAM is certainly really powerful, it is short of a GUI* (except for results-visualisation), and might therefore be less than ideal. That said, it is simple enough to use with a walkthrough, and the fact that the interface is basically composed of text files should make it easier for students to get back on track if they go wrong (this is a big problem, for example, with teaching CFX). If the main focus of the work is going to be running an essentially pre-built model (which the students then rebu
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Code_Saturne (Score:4, Informative)
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Try XFOIL... leave CFD for later (Score:2, Informative)
As an aerospace engineering PhD, I can tell you that CFD with mesh generation, turbulence model selection, numerical method selection, etc. is definitely above the level of your typical 11th grade student, even a gifted one. At best, you could have them run OpenFOAM tutorial cases, though it is highly doubtful that they would understand what is actually going on and would be able to say little more than "I've run a CFD code before, but I don't know what the results mean" at the end of the experience. Ther
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On that note, JavaFoil is pretty nice. It gives you some decent numerical results for airfoil testing. I used it in one of my college fluids classes to help with some airfoil calculations.
http://www.mh-aerotools.de/airfoils/javafoil.htm [mh-aerotools.de]
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This is the advice you want to follow. Use XFOIL or some other panel method based program to analyze airfoils along side of your wind tunnel stuff.
You can talk about all the things it doesn't do well (boundary layer separation, transonic flow...) and show them some Color Fancy Drawings made by a more advanced simulation as an aside.
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the teacher could run the CFD software (Score:2)
Most CFD software is too complex to learn in a reasonable timeframe in a classroom environment, but that doesn't mean the teacher can't learn it, set it up and run it to demonstrate the results to the kids. They won't need to understand the Navier-Stokes equations, they just need to see what can be done computationally, using equations based on the physics that they are learning in school.
Good idea, but very hard to do well... (Score:4, Insightful)
I like the idea of exposing your students to CFD packages, particularly the variation between experimental results & results off of a theoretical model. My concern would be that mastering a CFD package (or even become a basic user of one) is pretty time consuming. As others have pointed out you usually don't touch CFD packages until late undergrad or grad school.
Consider building the models yourself and running them as a demonstration rather than asking your students: They get the benefits of seeing what the software can do & being able to reference the theoretical data generated, but won't have to deal with the frustration/learning curve of CFD software.
If there's an interest you can offer an extra credit project where students design (or modify) a mesh & report the results.
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This one JAVA Virtual Wind Tunnel is interesting.
As a trainee physics teacher... (Score:2)
Some have suggested that we will not be able to teach this level of physics to this level of students. However if something comes up which can be used for simple attractive demonstrations then that would be great.
E.g in my course my students need to know the difference between laminar and turbulent flow, and fast move fluids will break into turbulent flow
San Le's Free FEA / CFD (Score:2)
http://slfcfd.sourceforge.net/ [sourceforge.net]
I haven't used it, but I've used his related SLFFEA [sourceforge.net] for a project before, and was surprised how easy it was to use.
JavaFoil (Score:3, Informative)
Basically, this is similar to XFoil, which is the standard 2-D CFD software for beginning Aeronautical Engineers (after they made us write our own...in FORTRAN77).
Since it is not 3-D, it runs MUCH faster and lets them discover the basics of pressure over an airfoil, which is the important part of wing design. The details of taper, sweep, tip shape, twist, and such are a bit too much for a high-school project. Surface area and aspect ratio are the simplest and most important criteria for airplane design. These values can be calculated on paper after coefficients of lift and drag are generated.
Javafoil can be run stand-alone or in an applet. It's free, and fairly straightforward to use.
Best of luck. I'd be interested to hear how quickly they catch on to the concepts.
http://www.mh-aerotools.de/airfoils/javafoil.htm [mh-aerotools.de]
'Ease of use' relative (Score:4, Interesting)
I've taught computational fluid dynamics and molecular dynamics workshops to university faculty members and can say this: You need to setup the examples for them to play with BEFORE class. There's really no such thing as an easy to use CFD or MD package, especially when looking at what it takes to setup initial conditions. I would strongly recommend that you do a good deal of the leg work, especially for participants that do not have the mathematical background or a background in fluid dynamics, period. It will only help you in the end.
This link [cfd-online.com] will take you to lists of free and free-to-academics CFD codes, but the free ones are really, really bare bones in a lot of cases when it comes to UI. I would not turn high school students loose on these codes without pre-determined examples.
FUN3D (Score:2)
NASA has several Open Source CFD packages. Unlike the ones developed by the regular OSS community (which may technically be superior), NASA Langley's CFDs are used by engineers there in real aircraft design. No matter what problems there may be (and there are sure to be some), they have to be "good enough" for real-world commercial aviation. That is certainly good enough for a physics lab.
The problem with other CFD packages is that even if they produce good results, unless you analyze the code, you can't be
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Fascinating to a point, there is a large community of amateur scientists who have made what are called <url:http://en.wikipedia.org/wiki/Fusor
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Yes, they are, but that doesn't make them correct and it doesn't mean anyone can be certain of their correctness, unless they spend time analyzing all the code arcs and constructing the model they actually use (versus the model intended by the author(s)) and =then= comparing that model against the formulation of the Navier-Stokes equation within the specific parameters concerned. (Almost nobody implements the generic equations, any CFD you find is going to be a simplified special-case version.)
Now, if you w
I am getting old.... (Score:1, Offtopic)
CFD or Load Analysis? (Score:2, Informative)
Are you looking for real CFD software for pressure distributions or are you looking for something that returns lift, drag, side and moments?
On the CFD side: OpenFOAM. Learning this is quite a bit of work because you need to work with meshing, boundary conditions, etc. But I would be very surprised you really want flow visualisation.
For loads: XFOIL or AVL (Athena Vortex Lattice, http://web.mit.edu/drela/Public/web/avl/ [mit.edu]). AVL allows 3D visualisation of loads, perturbations, etc. When it comes to a first
Here are two great CFD packages for airfoil sim (Score:5, Informative)
X-plane flight simulator (Score:2)
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Of course [pulse-jets.com], simulation is only one solution [barnstormers.com].
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Unfortunately, no, X-plane does not do CFD. You have to generate the airfoil's characteristics in something like X-Foil to create an airfoil file for the program. It is essentially a flat text file of lift coefficients vs angle of attack. Xplane breaks the lifting surfaces into narrow panels, and then adds up all the various lifts in real time.
CFD in real time would be way to computationally heavy.
Maximize the learning experience (Score:1)
Airfoils (Score:2, Interesting)
If you're looking for an airfoil simulator, you might try NASA's FoilSim II [nasa.gov]. "Elementary," student, and undergraduate versions are available, and the non-applet download gives an even more complete version that allows file output. While it's not a full CFD package, it may be good enough for an introduction to airfoil analysis. And while it's not open source, it is free and in the public domain (since it was government produced).
Also, if you're generally looking for open source physics simulations, you sho
Fully Powered CFD ? Try Blade Element Momentum ! (Score:1)
Well a CFD-System for just verifing wind tunnel tests might be a bit too much, but verifying lift and drag for such airfoils is possible.
This is based on my experience in the wind industry, so this means I'm refering to blades which consists of many airfoils attached to a rotor but the basic principles remain the same.
When dealing with windturbine aerodynamic simulations Aerodyn[3] implements the BEM[1] but BEM is based on MT[2] and can caculate Lift/Drag for Airfoils due to a certain wind either constant o
Gerris Flow Solver (Score:1, Interesting)
I recommend gerris flow solver for something that is fairly easy to use.... http://gfs.sourceforge.net/wiki/index.php/Main_Page
30 minutes after building it I had this: http://myrandomnode.dyndns.org:8080/~gmaxwell/theora/hot_xiph.ogv
and I think I spent more time figuring out how to build models in blender. It's not as powerful as openfoam, which is what I normally use now.... but its easier to get started with.
enGrid, OpenFOAM and others (Score:1)
For mesh generation (surface+volume meshing, boundary layer creation, etc):
enGrid: http://engits.eu/cms/index.php?id=4 [engits.eu]
netgen (used as a library in enGrid): http://www.hpfem.jku.at/netgen/ [hpfem.jku.at]
For the CFD simulations:
http://www.openfoam.com/ [openfoam.com]
Debian/Ubuntu packages:
https://launchpad.net/~cae-team/+archive/ppa [launchpad.net]
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X-Foil (Score:2)
Wooden models, water tank, food dye (Score:2)
Elmer (Score:1)
Tutor from Zeus Numerix (Score:1)
You can do this easily with physical models (Score:1)
You can do this easily with physical models held in place by a stand, colored smoke from smoke bombs or even dry ice, and a fan. What you are looking for is turbulence. Which is easy to spot as the smoke passes the variaous parts of the model. It shows up as swirls.
Cadium (which uses OpenFOAM) (Score:1)