Consider the flow field generated by two sources, both with strength $"$m$",$ located at the points $($x$,$y$)=(0,$a$),$ as shown in the figure. What is the volume flow in this flow field through an arc with its center at the origin, extending from the point $($x$,$y$)=(2$a$,$a$)$ to the point $($x$,$y$)=(2$a$,$a$)?$

According to the solution, the answer should be Q$=$ m$/4$ but please explain how to arrive at this and why, step by step.

The subject of fluid mechanics