Trying to organize

docs/source/FluidEquations.rst

+Here we describe the fluid variables, the governing equations, and the time discretization
+of the fluid evolution.
+
 Fluid Variables
 ===============
 
@@ -33,3 +36,11 @@ Conservation of fluid volume:
 
 .. math:: \frac{\partial \varepsilon_g}{\partial t} + \nabla \cdot (\varepsilon_g  U_g)  = 0
 
+Time Discretization
+===============
+
+In the absence of reactions, we assume that the fluid density is unchanged.
+
+We compute the fluid volume fraction directly from the particle locations.
+
+Thus here we focus on the discretization of the momentum equation

docs/source/Fluids.rst

+.. _Chap:Fluids
+
+Solving the Fluid Equations
+===========================
+
+.. toctree::
+   :maxdepth: 1
+
+   FluidEquations
+

docs/source/Particles.rst

+.. _Chap:Particles
+
 Particles
 =========
 
@@ -22,7 +24,7 @@ particle-particle, particle-fluid, and particle-wall interactions.
    :caption: Contents:
 
    ParticleBasics
-   ParticleFuild
+   ParticleFluid
    ParticleWalls
 
 

docs/source/index.rst

@@ -17,16 +17,13 @@ active development in the develop branch. Changes are merged into
 the master branch at the beginning of each month.
 
 .. toctree::
-   :maxdepth: 2
+   :maxdepth: 1
    :caption: Contents:
 
    Introduction
    GettingStarted
-   FluidEquations
+   Fluids
    Particles
-   ParticleBasics
-   ParticleFluid
-   ParticleWalls
 
 Notice
 ------