Defining the Absorption Coefficient Based on Wavelength in FLOEFD

When modeling radiation properties in FLOEFD, it is often necessary to define the absorption coefficient as a function of wavelength. This ensures accurate thermal and optical simulations, particularly in applications involving light interactions with materials. This article outlines the step-by-step workflow for setting up a user-defined solid material with wavelength-dependent absorption properties.

Setting Up a Material with a Wavelength-Dependent Absorption Coefficient

To define the absorption coefficient based on wavelength, follow these steps:

1. Create a New Solid Material

• In the project, navigate to "Solid Material."
• Click "Insert Solid Material," then select "Create/Edit."

2. Define a User-Defined Solid

• Open the "Solids" section.
• Create a "User Defined" solid material.

3. Enable Radiation Properties

• Activate the "Radiation Properties" option.
• This will allow the material to interact with radiation in the simulation.

4. Define the Absorption Coefficient

• Click on the "Tables and Curves" tab.
• From the dropdown menu, select "Absorption Coefficient."
• Use the table to input absorption values corresponding to different wavelengths.

By following this workflow, the material will be set up to absorb radiation differently across various wavelengths, enabling more precise thermal and optical analysis.

Understanding the Absorption Coefficient in FLOEFD

In FLOEFD, the absorption coefficient (α) is expressed in units of 1/mm. This unit represents the fraction of radiation absorbed per unit length as it propagates through the solid material. The absorbed radiant energy contributes to heat conduction calculations within the material.

Unlike some sources that may express absorption as a percentage, FLOEFD requires it in 1/mm. If the absorption coefficient is provided as a percentage, it is recommended to contact the source of the data for clarification. Once the methodology behind the percentage values is understood, they can be converted into the required units for FLOEFD.

Additional Resources

For further details, refer to the FLOEFD tutorial for LEDs, which provides additional guidance on defining radiation properties:
FLOEFD Tutorial – LED Radiation Properties

Conclusion

Defining a wavelength-dependent absorption coefficient in FLOEFD is essential for accurate radiation and heat transfer simulations. By creating a user-defined solid material, enabling radiation properties, and specifying absorption values through tables and curves, the required setup can be achieved. Understanding the correct unit (1/mm) for the absorption coefficient ensures proper implementation and reliable results.