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\begin{document}

Consider the compressible Navier--Stokes equations
\begin{align} 
\left.
\begin{aligned}
	\partial_t \rho + \nabla\cdot (\rho u) &= 0 \\
	\partial_t (\rho u) + \nabla\cdot(\rho u\otimes u) &= \Delta (\rho u)
\end{aligned}
\right\}&
& &\text{for } x\in\Omega,\ t>0 \label{eq:navier-stokes} \\
\left.
\begin{aligned}
	\rho(x,0) &= \rho_0(x) \\
	u(x,0) &= \frac{m_0(x)}{\rho_0(x)}
\end{aligned}
\right\}&
& &\text{for } x\in\Omega. \label{eq:initialdata}
\end{align}
\end{document}