What are equivalent shape methods?
A regular body can be specified by a few geometric parameters related to size (e.g., sphere diameter or side length of cube). A typical method for quantifying regular shapes is from the simple relationship between dimensions and geometric properties such as volume and surface area.
For irregularly-shaped particles, shape is usually defined using equivalent shape methods. Developing an equivalent-shape model is requires establishing and equating geometrical properties of the irregular shape to the known geometrical properties of the regular shape. The regular shape is referred to as the “equivalent regular shape” particle with the same selected geo-properties as the irregular-shaped particle. One-parameter equivalent shapes are defined by only one geometrically, two-parameter models by two properties, etc. A popular one-parameter models is an equivalent volume sphere where diameter is determined by equating the volume of the irregular particle to the sphere.