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spline segment refinement parameter ('maxh') not working?
2 years 9 months ago #3874
by place
spline segment refinement parameter ('maxh') not working? was created by place
i have made a generic wing shape using splines, it works as expected.
except....
the splines have an unreasonably small mesh division but when i alter the 'maxh' parameter on the 'AddSegment' call, it makes exactly no difference.
am i doing it right? any examples of altering mesh size on splines?
code for images. (many other cut-down/simplified things tried.)
except....
the splines have an unreasonably small mesh division but when i alter the 'maxh' parameter on the 'AddSegment' call, it makes exactly no difference.
am i doing it right? any examples of altering mesh size on splines?
code for images. (many other cut-down/simplified things tried.)
Code:
from netgen.geom2d import SplineGeometry
def AddSpline(spline,pts,**args):
idxs=[geo.AppendPoint(*pnt) for pnt in pts]
for i in range(0,len(idxs),2):
spline.AddSegment([idxs[i],idxs[(i+1)%len(idxs)],idxs[(i+2)%len(pts)]],**args)
return
geo = SplineGeometry()
geo.AddRectangle( (0, -2), (10, 2), bcs = ("top", "outlet", "bottom", "inlet"))
pts=[(0.3,0),(1.1,0.02),(1.1,0),(1.1,-0.05),(0.6,-0.06),(0.2,-0.07),(0.2,-0.02),(0.2,0)]
AddSpline(geo,[[pt[0],pt[1]+.25] for pt in pts],bc="obstruction",maxh=4.0,leftdomain=1, rightdomain=0)
AddSpline(geo,[[pt[0],-pt[1]-.25] for pt in pts],bc="obstruction",maxh=4.0,leftdomain=0, rightdomain=1) # reflection so swap domains
mesh = Mesh( geo.GenerateMesh(maxh=4.0))
2 years 9 months ago - 2 years 9 months ago #3876
by matthiash
Replied by matthiash on topic spline segment refinement parameter ('maxh') not working?
Hello,
The local mesh size is also affected by the edge curvature. You can reduce this factor like this:
But be aware that too large elements at strongly curved regions might lead to meshing failures or odd results after curving elements.
Best,
Matthias
The local mesh size is also affected by the edge curvature. You can reduce this factor like this:
Code:
mesh = Mesh( geo.GenerateMesh(maxh=4.0, curvaturesafety=0.1))
But be aware that too large elements at strongly curved regions might lead to meshing failures or odd results after curving elements.
Best,
Matthias
Last edit: 2 years 9 months ago by matthiash.
The following user(s) said Thank You: place
2 years 9 months ago #3877
by place
Replied by place on topic spline segment refinement parameter ('maxh') not working?
thanks, that's a ~100x speedup. (~5x element count reduction) with the 0.1 value of 'curvaturesafety', with the result visually very similar, but i will check the effect it has on bulk stuff, lift/drag.
from what i can tell, and from its name, 'curvaturesafety' operates to 'switch on' extra refinement when/where some curve-edge fit error is above a threshold.
but...
this goes to explain the behaviour that 'maxh' has no effect if 'curvaturesafety' has already refined smaller, but only if is being applied first. i would have expected 'maxh' to be applied first then 'curvaturesafety' as a safety-net after, can these be applied the other way round? or am i misunderstand completely.
from what i can tell, and from its name, 'curvaturesafety' operates to 'switch on' extra refinement when/where some curve-edge fit error is above a threshold.
but...
this goes to explain the behaviour that 'maxh' has no effect if 'curvaturesafety' has already refined smaller, but only if is being applied first. i would have expected 'maxh' to be applied first then 'curvaturesafety' as a safety-net after, can these be applied the other way round? or am i misunderstand completely.
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