non_darcy_formulas_disturbed.tex

\documentclass[11pt,a4paper]{scrartcl}\usepackage{amssymb,bm}\usepackage{amsmath}
%\usepackage{color}
\usepackage{xcolor}
\begin{document}
%\begin{equation}\pi(1)=\frac{length}{height }\end{equation}
\begin{align}
%\pi(1) &= \frac{length}{height }
M \ddot{z} &= (P_{bag} - P_{atmo})A - Mg \\
\dot{P}_{bag} &= \frac{\gamma R T}{A (z+\textcolor{purple}{w_{height}})} (\dot{m}_{in} - \dot{m}_{escape} - \frac{P_{bag} A \dot{z}}{R T})\\[20pt]
\rho_{atmo} \frac{\partial P}{\partial x} &= \beta(\frac{\dot{m}_{escape}}{A_e})^2 + \mu(\frac{\dot{m}_{escape}}{A_e}) \\
A_{e} &= Per * (z+\textcolor{purple}{w_{height}}) + W*\textcolor{blue}{w_{gap}} \\
\frac{\partial P}{\partial x} &= \frac{P_{bag} - P_{atmo}}{\ell}
\end{align}

\end{document}