\begin{align}
\mathbf{u}=(u(x,y,t),v(x,y,t))
\end{align}
then general form of Euler equation can be defined as
\begin{align*}
\rho\bigg(\frac{\partial}{\partial t}+\mathbf{u} \cdot \nabla\bigg)\mathbf{u}+\nabla p=0, \\
\nabla\cdot\mathbf{u}=0.
\end{align*}
Hi
I want to align all my equations ...