\begin{table}%T1
%\centering
\par
\caption{This table shows the critical flow value for which below this value the flow is absolutely unstable and above this value it is convectively unstable, in the three cases studied in the previous sections.}
\label{summary}
\begin{tabular}{ll}\hline \hline
& $U_{\rm c}$ \\
\hline
Incompressible & $0.38$ \\
Compressible & $0.37$ \\
Viscous & $0.31$ \\
\hline
\end{tabular}
\par
\end{table}