Understanding Non-Homogeneous Material

A non-homogeneous material is the association between a graded material file and a solid body using a coordinate system.

The goal is to define the index of refraction and/or absorption for specific locations in the material volume.

Graded Material

The Graded Material file describes the spectral variations of refractive index and/or absorption regarding the position in space.

Note: The data for the refractive index variation and the absorption variation generally come from Fluent.

As each wavelength propagates differently in a medium according to the refractive index and/or the absorption, you need for each wavelength:

  • a 3D table representing the refractive index variation in space (V list)
  • a 3D table representing the absorption variation in space (W list)
Each n in a table represents a 3D zone with its own refractive index. So, a wavelength propagates according to the refractive index of the 3D zone n. The same goes for absorption.

Non-Homogeneous Material Result Example

Figure 1. Interactive simulation showing the propagation inside a graded material
Figure 2. Direct simulation showing the propagation result at different location in the graded material

Maximum Number of Surface Interactions

Maximum number of surface interactions has a direct impact on the length of the propagation.

The minimum length of one 3D zone is considered for the propagation: 5% of this length is used to calculate the propagation step. It means that the status of the ray is checked every 5% of the minimum length of one 3D zone and its direction is changed according to the refractive index variation.

When the 3D table representing the variation has a high resolution, the Maximum number of surface interactions option must be high (otherwise rays are stopped) and it has a direct impact on the simulation time.

Maximum number of surface interactions = 100 Maximum number of surface interactions = 500 Maximum number of surface interactions = 5000