Solid waste shape description and generation based on spherical harmonics and probability density function.

Area of Science:

• Engineering
• Materials Science
• Computational Science

Background:

• Accurate modeling of solid waste transport and separation using discrete element methods (DEM) necessitates precise particle shape characterization.
• Current methods for acquiring morphological data are laborious and require numerous realistic samples, highlighting a need for efficient alternatives.

Purpose of the Study:

• To propose a novel, frequency-based method utilizing spherical harmonics (SHs) for describing solid waste particle shapes.
• To introduce a new shape generation technique that creates variations of a particle's shape based on its SH description and a probability density function.

Main Methods:

• A frequency-based shape description method using spherical harmonics (SHs).
• A shape generation method employing a probability density function controlled by a dimensionless factor (η) to create shape variations from a single particle's SH description.

Main Results:

• The proposed SH method adequately describes complex metal and plastic scrap shapes with 15° expansion and minimal divergence (within 0.1 mm).
• Testing with five values of η demonstrated the generation of shapes with distributions matching the original particle, with increasing η leading to greater morphological variation.

Conclusions:

• The developed spherical harmonics-based shape description and generation methods offer an efficient and accurate alternative to existing techniques.
• These advancements significantly improve the fidelity of discrete element modeling for solid waste transportation and separation processes.