Composite object in Gmsh
 

Hello,
I am new to Gmsh. I want to create a sphere inside a sphere.
Sphere1 = (0,0,0,rad = 1)
Sphere2 = (0,0,0,rad = 0.25)

The mesh should have continuity. I mean it is a composite object with a spherical inclusion inside a bigger sphere. Also I want a more denser meshing for the inner sphere.

Can some one tell me how to do it?

Thanks