# [Gmsh] Swiss cheese with filled cavities

Achille Pluplu mail.plutus at gmail.com
Thu Mar 30 18:44:14 CEST 2017

```Dear all,

I'm quite new to GMSH so, please, be patient.
I need to create a 3D mesh of a cube that include some inclusions
(spheres) of a different material.

I could find the following script that generates a cube with 5
cavities, but how can I mesh also the inclusions? In particular I need
two well separated meshes, one for the "cheese" the other for the
inclusions

Thanks a lot for helping!

Function CheeseHole

// In the following commands we use the reserved variable name
// `newp', which automatically selects a new point number. This
// number is chosen as the highest current point number, plus
// one. (Note that, analogously to `newp', the variables `newc',
// `news', `newv' and `newreg' select the highest number amongst
// currently defined curves, surfaces, volumes and `any entities
// other than points', respectively.)

p1 = newp; Point(p1) = {x,  y,  z,  lcar3} ;
p2 = newp; Point(p2) = {x+r,y,  z,  lcar3} ;
p3 = newp; Point(p3) = {x,  y+r,z,  lcar3} ;
p4 = newp; Point(p4) = {x,  y,  z+r,lcar3} ;
p5 = newp; Point(p5) = {x-r,y,  z,  lcar3} ;
p6 = newp; Point(p6) = {x,  y-r,z,  lcar3} ;
p7 = newp; Point(p7) = {x,  y,  z-r,lcar3} ;

c1 = newreg; Circle(c1) = {p2,p1,p7};
c2 = newreg; Circle(c2) = {p7,p1,p5};
c3 = newreg; Circle(c3) = {p5,p1,p4};
c4 = newreg; Circle(c4) = {p4,p1,p2};
c5 = newreg; Circle(c5) = {p2,p1,p3};
c6 = newreg; Circle(c6) = {p3,p1,p5};
c7 = newreg; Circle(c7) = {p5,p1,p6};
c8 = newreg; Circle(c8) = {p6,p1,p2};
c9 = newreg; Circle(c9) = {p7,p1,p3};
c10 = newreg; Circle(c10) = {p3,p1,p4};
c11 = newreg; Circle(c11) = {p4,p1,p6};
c12 = newreg; Circle(c12) = {p6,p1,p7};

// We need non-plane surfaces to define the spherical holes. Here we
// use ruled surfaces, which can have 3 or 4 sides:

l1 = newreg; Line Loop(l1) = {c5,c10,c4};   Ruled Surface(newreg) = {l1};
l2 = newreg; Line Loop(l2) = {c9,-c5,c1};   Ruled Surface(newreg) = {l2};
l3 = newreg; Line Loop(l3) = {c12,-c8,-c1}; Ruled Surface(newreg) = {l3};
l4 = newreg; Line Loop(l4) = {c8,-c4,c11};  Ruled Surface(newreg) = {l4};
l5 = newreg; Line Loop(l5) = {-c10,c6,c3};  Ruled Surface(newreg) = {l5};
l6 = newreg; Line Loop(l6) = {-c11,-c3,c7}; Ruled Surface(newreg) = {l6};
l7 = newreg; Line Loop(l7) = {-c2,-c7,-c12};Ruled Surface(newreg) = {l7};
l8 = newreg; Line Loop(l8) = {-c6,-c9,c2};  Ruled Surface(newreg) = {l8};

// We then store the surface loops identification numbers in a list
// for later reference (we will need these to define the final
// volume):

theloops[t] = newreg ;

Surface Loop(theloops[t]) = {l8+1,l5+1,l1+1,l2+1,l3+1,l7+1,l6+1,l4+1};

thehole = newreg ;
Volume(thehole) = theloops[t] ;

Return

lcar3 = .055;

hloc = 0.1;
Point(1) = {0, 0, 0, hloc};
Point(2) = {1, 0, 0, hloc};
Point(3) = {1, 1, 0, hloc};
Point(4) = {0, 1, 0, hloc};

Point(5) = {0, 0, 1, hloc};
Point(6) = {1, 0, 1, hloc};
Point(7) = {1, 1, 1, hloc};
Point(8) = {0, 1, 1, hloc};

Line(1) = {1,2};
Line(2) = {2,3};
Line(3) = {3,4};
Line(4) = {4,1};

Line(5) = {5,6};
Line(6) = {6,7};
Line(7) = {7,8};
Line(8) = {8,5};

Line(9)  = {1,5};
Line(10) = {2,6};
Line(11) = {3,7};
Line(12) = {4,8};

// bottom
Line Loop(21) = {-1,-4,-3,-2};
Plane Surface(31) = {21} ;

// top
Line Loop(22) = {5,6,7,8};
Plane Surface(32) = {22} ;

// left
Line Loop(23) = {1,10,-5,-9};
Plane Surface(33) = {23} ;

// right
Line Loop(24) = {12,-7,-11,3};
Plane Surface(34) = {24} ;

// front
Line Loop(25) = {2,11,-6,-10};
Plane Surface(35) = {25} ;

// back
Line Loop(26) = {9,-8,-12,4};
Plane Surface(36) = {26} ;

// We can use a `For' loop to generate five holes in the cube:

x = 0 ; y = 0.75 ; z = 0 ; r = 0.09 ;

For t In {1:5}

x += 0.166 ;
z += 0.166 ;

// We call the `CheeseHole' function:

Call CheeseHole ;

// We define a physical volume for each hole:

Physical Volume (t) = thehole ;

// We also print some variables on the terminal (note that, since
// all variables are treated internally as floating point numbers,
// the format string should only contain valid floating point format
// specifiers like `%g', `%f', '%e', etc.):

Printf("Hole %g (center = {%g,%g,%g}, radius = %g) has number %g!",
t, x, y, z, r, thehole) ;

EndFor

theloops = newreg ;

Surface Loop(theloops) = {31,32,33,34,35,36};

Volume(100) = {theloops[]};

Physical Volume (10) = 100 ;

```