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airinnova / pytornado

:airplane: An implementation of the vortex-lattice method (VLM)
https://pytornado.readthedocs.io/
Apache License 2.0
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Results do not match with Matlab Tornado #18

Open bharswami opened 4 years ago

bharswami commented 4 years ago

Attaching JSON files (template_singlewing.txt, template_state.txt, template.txt) and *.mat file (singlewing.zip) of the single-wing. Please verify if both results are the same - between MATLAB and pyTornado. I notice difference.

Numerical results in global forces/moments do not seem to match exactly.

singlewing.zip template_singlewing.txt template_state.txt template.txt

See issue initially reported here: https://github.com/airinnova/pytornado/issues/14#issuecomment-575512257

bharswami commented 4 years ago

With regard to different VLM methods, which is most accurate? I notice large difference between free stream following wake and fixed wake methods in Matlab Tornado itself. Matlab Tornado has option to do both.

aarondettmann commented 4 years ago

Well, it's all one method (the VLM). The difference simply lies in how the wing and the wake are modelled using vortex elements, i.e. different levels of "geometric" approximations. I am aware of three ways to define the vortex elements, but I am not aware of any literature that discusses these different approximations systematically. But it sounds a bit concerning if there are large differences between the different discretizations.

bharswami commented 4 years ago

When you try out freestream-wake versus fixed wake, please be sure to compare the moment values.

On Sat, Jan 18, 2020 at 8:18 PM Aaron Dettmann notifications@github.com wrote:

Well, it's all one method (the VLM). The difference simply lies in how the wing and the wake are modelled using vortex elements, i.e. different levels of "geometric" approximations. I am aware of three ways https://github.com/airinnova/pytornado/issues/14#issuecomment-575882972 to define the vortex elements, but I am not aware of any literature that discusses these different approximations systematically. But it sounds a bit concerning if there are large differences between the different discretizations.

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