Vortex

Today in Fluid Mechanics I learned that when streamlines are circular this signifies the presence of a vortex. Our professor wanted to show us the miracle of the vortex, as if we haven't already seen one, you know, all the time, so he stopped lecture to go to his office and find the classic dual coke bottle 'hour glass' filled partially with water. This silliness coming from the professor who has absolute disgust for any questions posed during his lecture; any sort of interruption clearly irritates this man, and off he disappears for roughly five minutes to find said instructional prop. When he returns, he shows us how the vortex forms and explains the fluid mechanics behind the phenomenon, which is amazing, I suppose, if you're in fourth grade. He then tells us that the particles nearer to the vortex move with a greater velocity than those farther away. And in order to more clearly illustrate the velocity gradient to the class, he said he should add some other distinct particles to the apparatus. Luckily, he had a jar of black pepper in his pants pocket. As soon as he pulled it out, I asked him (you must know how I love pepper), "Oh, you too carry around black pepper all the time?" He said to me, "Well, you're never know when you're going to need it." Truly, I say, a man after my own heart.