Creating Concentric spheres

[Jagir Hussan]

Hi,

     I wanted to created a volume mesh of three concentric spheres, since they intersect my naive attempt (below) did not work. Could you let me know how I could create such a mesh?

Thanks

Jagir

[no1,fc1]=meshasphere([0 0 0], 10, 1);

[no2,fc2]=meshasphere([0 0 0], 7, 1);

[no3,fc3]=meshasphere([0 0 0], 5, 1);

% combine 3 spheres and clean the surface

[no,fc]=surfboolean(no1,fc1,'union',no2,fc2,'union',no3,fc3);

[no_f,fc_f]=meshcheckrepair(no,fc(:,1:3),'meshfix');

plotmesh(no_f,fc_f,'y>0');

 

[Qianqian Fang]

On 09/10/2014 12:16 AM, Jagir Hussan wrote:

Hi,

     I wanted to created a volume mesh of three concentric spheres, since they intersect my naive attempt (below) did not work. Could you let me know how I could create such a mesh?

Thanks

Jagir

[no1,fc1]=meshasphere([0 0 0], 10, 1);

[no2,fc2]=meshasphere([0 0 0], 7, 1);

[no3,fc3]=meshasphere([0 0 0], 5, 1);

% combine 3 spheres and clean the surface

[no,fc]=surfboolean(no1,fc1,'union',no2,fc2,'union',no3,fc3);

hi Jagir

your spherical shells are not intersecting to each other.
the message from the surfboolean function (using libgts
in the backend) was erroneous.

the surfboolean feature is still experimental. apparently,
it (i.e. libgts) has problems even handling your simple
spherical meshes. In this case, I would roll back to the
simple mesh concatenation function, i.e. mergemesh(), by

[no,fc]=mergemesh(no1,fc1,no2,fc2,no3,fc3);

with the following command, I was able to get a good
3D multi-layered mesh from your example:

[node,elem]=surf2mesh(no,fc,[],[],1,2,[0 0 0;0 6 0;0 8 0]);
plotmesh(node,elem,'y>0')

mergemesh does not check for surface intersection,
so it is only safe to use when you know this is true.

Qianqian

[no_f,fc_f]=meshcheckrepair(no,fc(:,1:3),'meshfix');

plotmesh(no_f,fc_f,'y>0');

 

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[Jagir Hussan]

Hi Qianqian,

    Many thanks for the prompt response. The snippet you provided does what I need. 

Regards

Jagir