Improve Constant Offset Surface by adding smoothing

PlasmaControl / DESC

Stellarator Equilibrium and Optimization Suite

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Improve Constant Offset Surface by adding smoothing #820

Open dpanici opened 8 months ago

dpanici commented 8 months ago

https://faculty.cc.gatech.edu/~jarek/papers/localVolume.pdf

occasionally the offset surface, in regions of large concavity, can have self-intersections and non-smoothness. It could be possible to, at each zeta plane in the input grid, construct a 1D spline curve, calculate its curvature, then smooth over points with curvature not matching that of the original points on the surface (similar to the picture from the attached paper). May have to also do smoothing in the toroidal direction as well.

f0uriest commented 6 months ago

Another option is given in Attenberger, Houlberg, Hirshman 1987: https://www.osti.gov/servlets/purl/6566896

Basically make R{1,0} and Z{1,0} scale like (a + offset)/a and keep the others fixed, I think for strongly shaped boundaries you may want the other modes to decay a bit as you go away from the surface.

dpanici commented 3 weeks ago

https://arxiv.org/abs/2408.08267 has a method for smoothing a surface