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Old Jan 24, 2016, 09:25 AM
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Hy, I am having some trouble launching xoptfoil. I am using precompiled version for my windows 10. When i open the .exe file, black window flashes and then disappears. I also tried another computer... seems to be the same problem. What could be wrong? Should i try to compile it my self?
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Old Jan 24, 2016, 09:58 AM
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When you double click xoptfoil.exe, it will open a new command window and try to run it there, but if there's an error, the window will close right away and you won't be able to see what was wrong. Try first double clicking the "windows_command_prompt_here" file to open a command window yourself. Then type xoptfoil.exe, and when there is an error the window will stay open. Then you can report it here and I'll try to diagnose it for you.
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Old Jan 24, 2016, 11:21 AM
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Thanks!
I found the problem. Program didin't find the inputs.txt file and failed to launch.
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Old Jan 24, 2016, 11:29 AM
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Okay, great! It's usually better to run it from the command line in case there's an error. Also, if your processor has more than one core, it will run faster if you compile it yourself, because the particle swarm algorithm will be able to run in parallel.
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Old Jan 24, 2016, 01:21 PM
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Tip: in Explorer right click while holding shift: in the menu you'll now have the option: "Open command prompt here" .

This way you 'll start the command prompt in the current directory, instead of the root directory.

Clicking the "windows_cmd_prompt_here.bat" has the same function.
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Old Jan 29, 2016, 10:39 PM
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I just uploaded a new version to Sourceforge.
  • The main change is a Python script called design_visualizer.py which will plot the airfoils and polars that were generated during an optimization for you. It uses the <prefix>_design_coordinates.dat and <prefix>_design_polars.dat that are written out by the optimizer. You need to install Python to use it, which is not hard; instructions are in the User Guide.
  • The design_plotter tool has also been removed. The optimizer now writes out the coordinates and polars for each successively better airfoil while the optimization is running, so there's no need to perform the extra step of running design_plotter afterwards.
  • Documentation was also updated reflecting the new changes and some changes from the previous version that I forgot to update in the User Guide.
Next on my list is to enhance this design_visualizer.py tool so that it can monitor the progress of the optimization as it is going and automatically display the curent best design for you. After that will be allowing an optimization run to be restarted if it is terminated early. Attached is an example plot from design_visualizer.py.
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Old Feb 08, 2016, 05:53 AM
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Nice work Montag!!!
I am not cofident with Particle swarm optimization algorithm.
I have a simple question.....did you try to perform two time the analysis (keeping the same parameter) starting always from the same airfoil? Did you get the same optimized airfoil at the end? This could tell us the usefullnes and reliability of that approach.
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Old Feb 08, 2016, 07:07 AM
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Is it possibile to implement recombination/crossover between population during the evolution flow?
How big is the starting population in your algorithm?
I do not know, but starting with an high population, applying the particle swarm algorithm and then using the recombination between the best particles should give better results in few cycles.....
Am I right?
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Old Feb 08, 2016, 08:42 AM
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The particle swarm algorithm, like genetic algorithms, employs randomness in both generating the initial population and in the progression of the search after that. For sufficiently simple problems, it should always find the global optimum. However, airfoil optimization is a very difficult problem with lots of local optima, especially with the XoptFoil approach where several different operating points play into the objective function. For this problem, even a global searching method like particle swarm does not always find the absolute best possible design, though it does consistently find a very good design. If you were to eliminate all randomness from the algorithm, then of course it would always find the same answer, though it would probably not be the best possible answer.

As a test, you can try running a local search only (simplex algorithm without PSO first). The simplex algorithm is very efficient at finding the optimum design for unimodal problems, and it can also help to refine the solution of a multimodal problem when it starts near the global optimum value, which is why I usually run it after PSO in XoptFoil. If you run it by itself from the start, I think you will find that it gets stuck very quickly on a local optimum and doesn't find nearly as good an answer as PSO, so by this you know that PSO is doing its job.

Now, as far as getting a better answer more reliably with PSO for airfoil optimization, it is possible but will take some extra time. In the latest release, I've put in a setting called pso_convergence_profile. The default value is 'standard', which I think gives a good balance of search effectiveness and computational time. However, you can also switch it to 'exhaustive', which changes some internal PSO settings so that the particles don't converge as quickly and search more of the design space. This method consistently found better optimal designs in my testing, but you will have to increase the number of iterations to something like 800 or 900 instead of 200 or 300 (for the standard convergence profile) to give it time to converge. You can also experiment with using more particles in the population instead of the default 40, which will also increase the computation time. And finally, if you want the best possible design, it might pay off to run it multiple times with different seed airfoils.

Hope this was helpful.
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Old Feb 10, 2016, 11:52 AM
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Thank you for your exhaustive replay. In these days I try your program and you did an excellent work.
During my tests I found that two other options could be usefull...
1-insert the option of stop/pause the process
2-pawer off the PC once the process is finished.

I will play more with your program
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Old Feb 10, 2016, 06:08 PM
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Quote:
Originally Posted by Dareius View Post
Thank you for your exhaustive replay. In these days I try your program and you did an excellent work.
During my tests I found that two other options could be usefull...
1-insert the option of stop/pause the process
2-pawer off the PC once the process is finished.

I will play more with your program
One of the next things on my list is to implement read/write restart files so you can stop an optimization and come back to it later.
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Old Feb 10, 2016, 08:04 PM
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XoptFoil 1.7.1 is now available on Sourceforge. Here are the main improvements:
  • design_visualizer.py was mistakenly omitted from release v1.7.0. It is present in v1.7.1 and located in the bin directory.
  • design_visualizer.py can now monitor an ongoing optimization, so you can see the shape and polars for the current best airfoil and the seed airfoil while xoptfoil is running. Select option 3 in the menu of design_visualizer.py to use this function.
Sorry about the mixup on the last release. I have a packager script and forgot to update it to include design_visualizer.py, since it was a new file. Anyway, this progress visualization tool should be very valuable, I think, because now you're not just looking at numbers on a screen while XoptFoil runs.
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Old Feb 12, 2016, 09:23 AM
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There was a bug in design_visualizer.py that made it not run. I must have changed something right before uploading it and forgotten to test it again. Sorry about that! The bug is fixed in version 1.7.2, which is online now.
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Old Feb 23, 2016, 05:53 AM
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i am using this tool and It is amazing. Sometime, instead of airfoil optimization, I think you created a tool for new airfoil generation (but doesn't matter).
For some aifoils, I noted the program fail to start if i am setting a negative al.

moreover, trying to optimize some reflex aifoils I obtained very weird designs that doubtfully will work.

I suggest you add the naca 5 digit airfoil analysis.

Keep going with your program

All the best
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Old Feb 23, 2016, 09:48 AM
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Quote:
Originally Posted by Dareius View Post
i am using this tool and It is amazing. Sometime, instead of airfoil optimization, I think you created a tool for new airfoil generation (but doesn't matter).
For some aifoils, I noted the program fail to start if i am setting a negative al.

moreover, trying to optimize some reflex aifoils I obtained very weird designs that doubtfully will work.

I suggest you add the naca 5 digit airfoil analysis.

Keep going with your program

All the best
Hey Dareius,

I'm glad you like it. If you could give me some more details about what error you get when starting with negative alpha, I would appreciate it. I'm always trying to improve the tool, and in fact I'm working on a couple new features now including a genetic algorithm and the ability to restart a run that didn't finish. I'm also thinking about in the future creating a more user-friendly interface and installer, but that will take awhile to implement. I figure it could reach a much wider audience that way. The actual functionality is the most important, though, so I like to know about any bugs you may encounter.

As far as the funny shapes are concerned, a lot of times that has to do with getting the constraints set right, and sometimes it takes some trial and error. If you have specific cases that you want advice on, feel free to post the funny looking airfoils and/or input files here, and I can try to give advice on what to change.
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