# Theory

Below are paper and notes that explain the theory behind this package.

## Waves in multi-species

A summary on the equations to calculate effective wavenumbers in 2D and 3D acoustics in medium filled with many different types of randomly placed particles. These notes assume only whole-correction for the pair-correlation.

## Low frequency limit for multi-species

These notes deduce the effective properties and reflection coefficient for a plane wave in the limit of low frequency.

## Percus-Yevick hard spheres

These notes show how to efficiently calculate the Percus-Yevick pair-correlation for 2D hard spheres. That is, sphere which do not attract of repel each other.