Resumen de Vortex Apparatus and Demonstrations
Vortex flow, from millimeter to kilometer in scale, is important in many scientific and technological areas.1Examples are seen in water strider locomotion, from industrial pipe flow wastewater treatment to air traffic control safe distance between aircrafts on a runway ready for takeoff to atmospheric studies.2�5In this paper, we focus on a particular vortex known as bathtub vortex BTV. It occurs when water is drained from a hole at the bottom of a container such as a bathtub or a sink under the action of gravity. The vortex has a funnel shape with a central air core, resembling a tornado. We have designed a portable apparatus to demonstrate bathtub vortex on a continual basis. The apparatus consists of a clear cylinder supported by a frame over a water reservoir and a submersible pump. Young and old have been equally amazed by watching the demonstrations at various public presentations held at the University of the Pacific recently. With material cost of less than $100, the apparatus can be easily fabricated and used at other universities. With a short setup time, it is an ideal device for promoting science to the general public, and it can be used to enhance lectures in physics courses as well.
