[Gmsh] 2D meshing problem; extrude; 360 rotation; revolution solid.

Gustavo Charles Peixoto de Oliveira gustavo.oliveira at uerj.br
Thu Mar 26 21:05:16 CET 2015




Thank you Prof. Geuzaine!
I didn't think on it!
;)
Regards,
On Thu, March 26, 2015 15:14, Christophe
Geuzaine wrote:

>

>> On 26 Mar 2015, at 05:49, Gustavo Charles Peixoto de Oliveira

>> <gustavo.oliveira at uerj.br> wrote:

>>

>>

>>

>>

>> Dear Gmshers,

>>

>> I'm trying to generate a revolution solid from a cosine function
profile

>> and sequential 2D surface meshing. Although I could get to the
surface

>> after a rotation around the x-axis with the 'Extrude' command,
Gmsh

>> returns an error if I try to mesh this "apparently
closed" resulting

>> solid.

>>

>> My insight is that there's a problem with overlapped entities
after the

>> 2*pi rotation, however I can't get rid of the error. I tried a
full

>> rotation of 2*pi and 4 partial rotations of pi/2 with the same
profile,

>> but both the strategies haven't work, while non-overlapping
angles ( <

>> 2*pi) have produced the expected mesh.

>>

>> Could someone help me to understand what's going wrong and how
can I

>> have the mesh working? Or maybe an alternative way. The .geo is
like

>> below.

>>

>> Thankfully,

>>

>

> Extrude in 2 steps:

>

> /* Defaults */

> Geometry.Surfaces = 1; //

>

> /* Settings */

> x0 = 0.0;

> y0 = 0.0;

> z0 = 0.0;

> c1 = 0.05;

> amp = 0.05;

> r1 = 0.5*amp;

> t0 = 2.0;

> R0 = 0.5;

> lambda = 2*R0;

> L = lambda;

>

> /* Discretization */

> np = 10;

> nt = 10;

> dx = L/(np - 1);

> Geometry.ExtrudeSplinePoints = nt;

>

> // initial point

> X[0] = x0 - lambda/2;

> Y[0] = y0 + r1;

> P0 = newp;

> P[0] = P0;

> Point(P0) = {X[0],Y[0],z0,c1};

>

> // 'revolution' profile

> For p In {1:np-1}

> X[p] = X[0] + p*dx;

> Y[p] = Y[0] + amp*Sinh(t0)*(1.0 + Cos(2*Pi*X[p]/lambda) );

> Pp = newp;

> Point(Pp) = {X[p],Y[p],z0,c1};

> P[p] = Pp;

> L = newl;

> Line(L) = {P[p-1],P[p]};

> extr[] = Extrude{ {0,0,0}, {1,0,0}, {0,0,0}, Pi }{ Line{L};};

> extr2[] = Extrude{ {0,0,0}, {1,0,0}, {0,0,0}, Pi }{
Line{extr[0]};};

> EndFor

>

>

>

> --

> Prof. Christophe Geuzaine

> University of Liege, Electrical Engineering and Computer Science

> http://www.montefiore.ulg.ac.be/~geuzaine

>

>

>

>





--

Gustavo PEIXOTO DE OLIVEIRA, Dr.

State University of Rio de Janeiro 

 
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