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How to define a 3D geometry given the contour function f(x, y, z)?

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Hi,

I am trying to build a 3D lattice shown in the "geom.png" attachment. As seen, it is a binary composite lattice, where the grey volume is filled with material A, and the rest of the volume is filled with material B. Mathematically, this lattice is defined by the boundary function shown in the "func.png" attachment. When the function f(x, y, z) > 0, it is filled with material A, and material B, otherwise.

Up to now, my desired geometry should be clear (hopefully!). I have being trying to do this for the whole day, but no luck. I believe COMSOL definitely supports user-defined arbitrary geometry, as the built-in geometry primitives are just too limited.

I would appreciate if you could demonstrate how I can create such a geometry.

Thanks in advance!

Regards,
A. Wang


1 Reply Last Post 23.05.2014, 19:20 GMT-4
Robert Koslover Certified Consultant

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Posted: 1 decade ago 23.05.2014, 19:20 GMT-4
If you can express the surface (aka, boundary) between your materials as one or more parametric surfaces, you should be able to insert that surface (aka, boundary) into the geometry. Once those surfaces are there, you should be able specify material properties of the resulting domains in the usual way.

From the Comsol Reference Guide:
A parametric surface is a surface in 3D where you use two parameters to define the
coordinates of the surface... To create a parametric surface, right-click a 3D geometry and
select More Primitives>Parametric Surface( ). Then enter the properties of the parametric surface.."
If you can express the surface (aka, boundary) between your materials as one or more parametric surfaces, you should be able to insert that surface (aka, boundary) into the geometry. Once those surfaces are there, you should be able specify material properties of the resulting domains in the usual way. From the Comsol Reference Guide: A parametric surface is a surface in 3D where you use two parameters to define the coordinates of the surface... To create a parametric surface, right-click a 3D geometry and select More Primitives>Parametric Surface( ). Then enter the properties of the parametric surface.."

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