# General Description

Omnisoot consists of six sub-models:
* {ref}`reactors` provide zero-dimensional approximate representations of complex reactive flows in the form of ODE equations that track the changes in the mass and energy of gas phase, mass fraction of individual gaseous species, elemental (carbon and hydrogen) mass of solid particles, and number density of agglomerates and primary particles of solid particles.

* {ref}`particle_dynamics` describe morphological features of solid particles in terms of agglomerate characteristic diameters and calculate collision rate of particles. Particle dyanmics models determine the contribution of inception, surface growth, oxidation and coagulation to tracked particle properties depending on the assumptions on particle size distribution.

* {ref}`pahgrowthmodels` calculate the rate of inception and surface growth via PAH adsorption from aromatic precursors.

* {ref}`surface_reactions` uses hydrogen-abstraction-acetylene($\mathrm{C}_2\mathrm{H}_2$)-addition formulation to compute the rate of surface growth by $\mathrm{C}_2\mathrm{H}_2$ and oxidation by $\mathrm{O_2}$ and $\mathrm{OH}$.

```{figure} ../assets/images/structure.png
:width: 90%
:align: center
:name: fig-structure

The structure of Omnisoot package and sub-models.
```