# [Gmsh] making internal points part of the mesh

J Wheeler jwheeler at dmu.ac.uk
Fri May 10 18:14:34 CEST 2002

```Hello,

I have an electical impedance problem to solve which consists of several
electrodes suspended in a cyclindrical container of saline solution. I have
defined the electrode positions and the boundaries of the cylinder, but I
can't find a way of making the final mesh structure attach itself to the
electrode points. Is there a simple way of doing this?

The geometry file is as follows:

lc = 7;

Point(1) = {0, 0, 0, lc};                   // earth electrode
Point(2) = {8, 0, 12, lc};
Point(3) = {0, 8, 12, lc};
Point(4) = {-8, 0, 12, lc};
Point(5) = {0, -8, 12, lc};
Point(6) = {18, 0, 16, lc};
Point(7) = {12.728, 12.728, 16, lc};
Point(8) = {0, 18, 16, lc};
Point(9) = {-12.728, 12.728, 16, lc};
Point(10) = {-18, 0, 16, lc};
Point(11) = {-12.728, -12.728, 16, lc};
Point(12) = {0, -18, 16, lc};
Point(13) = {12.728, -12.728, 16, lc};
Point(14) = {28, 0, 27, lc};
Point(15) = {24.249, 14.000, 27, lc};
Point(16) = {14.000, 24.249, 27, lc};
Point(17) = {0, 28, 27, lc};
Point(18) = {-14.000, 24.249, 27, lc};
Point(19) = {-24.249, 14.000, 27, lc};
Point(20) = {-28, 0, 27, lc};
Point(21) = {-24.249, -14.000, 27, lc};
Point(22) = {-14.000, -24.249, 27, lc};
Point(23) = {0, -28, 27, lc};
Point(24) = {14.000, -24.249, 27, lc};
Point(25) = {24.249, -14.000, 27, lc};
Point(26) = {38, 0, 50, lc};
Point(27) = {35.107, 14.542, 50, lc};
Point(28) = {26.870, 26.870, 50, lc};
Point(29) = {14.542, 35.107, 50, lc};
Point(30) = {0, 38, 50, lc};
Point(31) = {-14.542, 35.107, 50, lc};
Point(32) = {-26.870, 26.870, 50, lc};
Point(33) = {-35.107, 14.542, 50, lc};
Point(34) = {-38, 0, 50, lc};
Point(35) = {-35.107, -14.542, 50, lc};
Point(36) = {-26.870, -26.870, 50, lc};
Point(37) = {-14.542, -35.107, 50, lc};
Point(38) = {0, -38, 50, lc};
Point(39) = {14.542, -35.107, 50, lc};
Point(40) = {26.870, -26.870, 50, lc};
Point(41) = {35.107, -14.542, 50, lc};
Point(42) = {20, 0, 175, lc};               // fixed electrode 1
Point(43) = {-20, 0, 175, lc};              // fixed electrode 2

Point(44) = {50, 0, 0, lc};                      // define base of phantom
Circle(1) = {44,1,44};
Line Loop(1) = {1};
Plane Surface(1) = {1};

Extrude Surface {1, {0,0,175}, {0,0,1}, {0,0,0}, Pi/2}
{
Layers {Floor(175/lc),100,1};
};

Surface Loop(1) = {1};
Volume(1) = {1};

Physical Point(1) = {1:44};

I hope you can help

Best regards

James Wheeler

======================
PhD Student
3D & Bio Medical imaging
SERCentre
De Montfort University
Leicester
UK
(0116) 255 1551 ext 8065
======================

```