Program running

General Discussion
1

Hello everyone
Good afternoon. I am new in freefem++, so I cannot run this in freefem++. Can anyone help to correct my program. Thanks in advance.

// Parameters
real r = 1; // Cylinder radius
real h = 2; // Cylinder height
int n = 32; // Number of segments (discretization along the circumference)
int m = 10; // Number of layers along the height

// Mesh generation
border b1(t=0, 2pi) { // Bottom circle
x = rcos(t);
y = r*sin(t);
}

border b2(t=0, 2pi) { // Top circle
x = rcos(t);
y = r*sin(t) + h;
}

// Creating the mesh from the borders
mesh Th = buildmesh(b1(n) + b2(n));

// Adding sides
// Add lateral surface based on the bottom and top borders
for(int i=0; i<n; i++) {
Th += triangle(b1[i], b1[(i+1)%n], b2[i]);
Th += triangle(b2[i], b1[(i+1)%n], b2[(i+1)%n]);
}

// Visualize the mesh
plot(Th);

2

Hello,
I do not understand the shape of the mesh you want to create. You have two disjoint circles, but then ? Do you want some kind of “stadium” ?

3

Hello,
Lines 8, 9, 13, 14 you miss a " * " (multiplication): ‘2 * pi’ and ‘r * cos(t)’
Lines 21-26 I don’t get the code. Have you defined a function triangle() somewhere else?

4

Thanks for your reply. Actually, I want to make a domain like cylinder by separating lower circle name and upper circle name. I want to use this domain for freefem++ simulation. I can make a cylinder domain but cannot by separating their circle names. Hope you understand. Thanks

NmrTdZms
NmrTdZms1536×2048 131 KB

5

Thanks for your reply. Actually, I want to make a domain like cylinder by separating lower circle name and upper circle name. I want to use this domain for freefem++ simulation. I can make a cylinder domain but cannot by separating their circle names. Hope you understand. Can you help me to find such domain? Thanks in advance.

NmrTdZms
NmrTdZms1536×2048 131 KB

6

to be sure of your code and avoid the copy/paste errors can you modify your initial post and put the code using the function “preformatted text” (ctrl+e) ?

7

Thanks for your reply. Actually, I want to make a domain like cylinder by separating lower circle name and upper circle name. I want to use this domain for freefem++ simulation. I can make a cylinder domain but cannot by separating their circle names. Hope you understand. Can you help me to find such domain? Thanks in advance.

8

Do you mean to make a cylinder in 3d ? or a 2d “stadium” like domain ?

9

Thanks. I want to make a cylinder in 3D. I want to name like as, the bottom circle (z = 0) will have label 1, the top circle (z = height) will have label 2, the curved surface of the cylinder will have label 3. But I cannot do that. Can you help me to make such domain? Thanks in advance.

10 
load "msh3"

// Parameters
real r = 1.; // Cylinder radius
real h = 2.; // Cylinder height
int n = 32; // Number of segments (discretization along the circumference)
int m = 10; // Number of layers along the height

// Mesh generation
border b1(t=0.,2.*pi){x = r*cos(t);y = r*sin(t);};
mesh disc=buildmesh(b1(n));

int[int] rdown=[0,1],rup=[0,2],rmid=[1,3];
mesh3 Th=buildlayers(disc,m,zbound=[0.,h],labeldown=rdown,labelup=rup,labelmid=rmid);

plot(Th);
11

Thanks for your reply and sorry for late reply. I understand your code. But how can I rename the boundary of surfaces. I want to rename as lower circle boundary ‘a’, upper circle boundary ‘b’ and cylinder surface ‘c’.
I can rename the lower boundary as follows,
border b1(t=0.,2.pi){x = rcos(t);y = r*sin(t); label=1;};
But I cannot rename the other boundary.
Can you help me to do this?

12

The labeling of the three boundaries is done as
int[int] rdown=[0,a],rup=[0,b],rmid=[1,c];
with a,b,c as you asked for.
The 0 refers to the interior of the disc, and the 1 refers to the boundary of the disc.

13

Thanks for your reply. I understand very clearly dear prof. Thanks for your clarification.