[Gmsh] Extruded spline surfaces show mesh artifacts near edges.

[Mark Starnes]

Hi again everyone,

Further to my last question, I'm finding that
using a spline with a single internal point
results in the bump transfinite line algorithm 
being affected by the position of the internal
point.  Is this expected behaviour?  I may have
changed my default settings.....

Example:

Point(1) = {0,0,0};
Point(2) = {0,0.5,0}; // internal point.  This is ok with bump.
// Point(2) = {0,0.9,0}; // internal point.  This affects bump.
Point(3) = {0,1,0};
Spline(4) = {1,2,3};

Transfinite Line{4} = 20 Using Bump 0.05;
Extrude {1, 0, 0} {Line{4}; Recombine;
Layers{10};}

Any comments would be appreciated.

Best regards,

Mark.


On Thu, Dec 01, 2011 at 03:47:26PM +0000, Mark Starnes wrote:
> Hi everyone,
> 
> I'm using an extruded spline to define a surface.
> On meshing, most of the surface is fine but there
> is behaviour I don't understand near the internal
> point of the spline.  This example shows something
> similar:
> 
> lc=0.001;
> Point(1) = {0,0,0,lc};
> Point(2) = {0.05,0,0,lc};
> Point(3) = {0.05-0.001,0.005,0,lc};
> Spline(5) = {2, 3, 1};
> Extrude {{0, 1, 0}, {0, 0, 0}, Pi/4} {Line{5};}
> 
> ... the elements near the internal spline point
> have edges that have left the surface and jumped
> across.  To be honest, this example is extreme;
> my real case merely shows a mesh of density that
> changes near my internal spline points.  
> 
> Am I doing something wrong?
> 
> Thanks for this great software.
> 
> Best regards,
> 
> Mark.
> 
> 
> 
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