Understanding transport phenomena—how ions, molecules, and charges move through materials—is essential to many fields in engineering. Yet the concepts can be difficult to grasp. In “A Teacher’s Guide to Classroom Demonstrations in Transport Phenomena,” David Leighton, professor of chemical and biomolecular engineering at the University of Notre Dame, provides 36 hands-on experiments designed to spark critical thinking about transport and the mathematical principles that drive it.
“When you see some of these demonstrations, there’s certainly a gee-whiz response, but I want students to also ask: why is this doing what it’s doing—how could I describe it quantitatively?” said Leighton.
Most of the demonstrations in Leighton’s book use equipment readily found in college laboratories—some require only household items. Each is designed to take 10 to 15 minutes of class time. These experiments complement Leighton’s undergraduate courses on mass, momentum and energy transport by clarifying complex concepts.
While most of the experiments are suitable for college-level instruction, some—such as those illustrating the Magnus lift and the Coandă effect—are also appropriate for advanced high school physics classes. These show how fast-moving objects in air or water can move unexpectedly sideways. A few, such as Moffatt eddies and Jeffery orbits, require an understanding of graduate-level mathematics for a quantitative description, but audiences at many levels find the visual effects engaging.
Involving students in classroom demonstrations is, according to Leighton, key to making transport courses effective, memorable and fun. He credits his own students with devising and carrying out many of the book’s experiments, noting that they are required to submit a one-page description of their planned demonstration to allow for a feasibility and safety check before proceeding.
An example of a demonstration first brought to Leighton’s classroom by his students involves antibubbles. While a regular soap bubble is a thin layer of liquid surrounding a pocket of air, an antibubble is a droplet of liquid surrounded by a thin layer of air.
Some demonstrations reveal unexpected forces at work. In one experiment, a red Skittle is placed in water. As the red coating dissolves, students assume it’s diffusion—but it’s actually gravity-driven flow, Leighton explains.
“Most of these demonstrations aren’t really original—but rather are repackaged in a way that could be used in a classroom with an analysis that is different or more complete,” said Leighton. “Really, the novelty of the book is that it makes it relatively easy for faculty to do effective classroom demonstrations. Live demos are always a little tricky, and this book makes the process more reliable.”
Leighton’s book is available on Amazon in black-and-white hardcover and paperback, as well as Kindle editions in color. A PDF is available upon request from the publisher, diffusivepress.org, reflecting the author’s intent to make educational materials available at little or no cost.
—Karla Cruise, Notre Dame Engineering