## THE VELOCITY FIELD

The animation of the velocity vector field confirms what has been shown in the stream function animation.

When circulation is zero, the uniform stream approaching from the right divides into two symmetric flows, one going over the cylinder, the other flowing under it. The two flows connect again downstream of the cylinder. The flow field is symmetric with respect to the x axis. Two fluid particles immediately above and below the upstream stagnation point travel the same distance around the cylinder and then meet again at the downstream stagnation point.

When circulation is increased, the stagnation points move towards the lower half of the cylinder so that the two companion fluid particles follow different routes to reach the downstream stagnation point.

In particular the fluid particle that travels above the cylinder makes a longer route with respect to its companion, but it travels fast enough to arrive at the same time at the downstream stagnation point.