A tube of uniform diameter $D$ is immersed in a steady flowing inviscid liquid stream of velocity $V$, as shown in the figure. Gravitational acceleration is represented by $g$. The volume flow rate through the tube is __________________.

1. $\dfrac{\pi}{4}D^{2}V$
1. $\dfrac{\pi}{4}D^{2}\sqrt{2gh_{2}}$
1. $\dfrac{\pi}{4}D^{2}\sqrt{2g\left ( h_{1} + h_{2}\right )}$
1. $\dfrac{\pi}{4}D^{2}\sqrt{V^{2} - 2gh_{2}}$