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May 10, 2001 Vatistas explores Homer's vortex





Georgios Vatistas

Georgios Vatistas

Photo by Andrew Dobrowolskyj


by Sylvain Comeau

Professor Georgios H. Vatistas is an expert on vortices—think of whirlpools—and one vortex that especially interests him comes out of ancient literature: Charybdis, the terrible sea monster that terrified the sailors in Homer’s Odyssey, written 800 years before the Christian era.

Not a suitable subject for scientific study? Vatistas says that vortices exist on every scale, from the very small (quantum mechanics) to the ordinary (classical mechanics) and the very large (relativistic mechanics).

A mythological creature does not exactly register in any of those disciplines. But in his latest paper, Escaping Charybdis’ Wrath, the professor of mechanical engineering examines whether there was a strong, sober dose of empirical scientific observation in mythological accounts of tidal whirlpools. Vatistas presented the paper at a recent symposium organized by the Department of Mechanical Engineering, and is submitting it to consumer science magazines.
“No one else in my field has looked at mythological accounts of vortices, as far as I know. Of course, this is not engineering, but the descriptions of the vortex are right on the money, in terms of the physics involved.”

For example, in The Odyssey, which Vatistas read in the original ancient Greek version, Charybdis has both sucking and belching phases every day. Odysseus, the protagonist, crossed the whirlpool during the sucking phase. As Vatistas points out in his paper, this is an early explanation of why ships can be sucked in, then reappear “in a disintegrated form.”

Vatistas also examined a short story by Edgar Allen Poe, A Descent into a Maelstrom, about a fisherman’s terrifying experiences inside a Norwegian whirlpool.

Vatistas points out that Homer and Poe must have been using empirical evidence, sometimes enhanced by their imaginations, most likely through accounts by sailors of the time. Poe correctly notes, for example, that “the larger the bodies, the more rapid their descent;” it is now known that gravity drives a boat down into a whirlpool, so heavier objects are the first to go.

Vatistas concludes his paper by wryly suggesting that the observations and experiences of fishermen and explorers of that time trump scientific observation in some ways.
“In spite of approximately 3,000 years of development in science, we find ourselves in the awkward position of not being able to suggest to Odysseus a substantially better navigational plan [around Charybdis].”

Mythology in science

Vatistas says that it is fitting to ferret out the science in mythology, since there is a fair amount of mythology in science.

“We take a lot of scientific axioms on faith; for example, ‘energy cannot be created or destroyed,’ which is a fundamental belief in physics.

“We accept it because it hasn’t been disproven. But it hasn’t been proven either; if that’s not mythology, what is? Often, we accept a set of rules based on our experiences, then we construct a theory that explains it. And if we learn that an axiom doesn’t explain everything, we come up with a better axiom. ”

His examination of Homer and Poe was essentially a change of pace from the work he usually does in fluid dynamics, which is the study of the forces involved in the flow of gases and liquids. Vortex research has been the focus of the bulk of his research in that field, from mathematical models to industrial applications.

Vatistas first made his mark in his PhD thesis, which he completed here at Concordia in 1984, in which he introduced what is now known as the Vatistas Vortex Model, a mathematical model for computer simulations of the velocity of any vortex, on any scale. He recently expanded on the original paper with one on a family of models in 1999.

In a recent project for Pratt and Whitney, Vatistas helped improve wind-tunnel testing for gas turbine engines. In a more surprising application of his mathematical models, Vatistas recently collaborated with medical researchers at the Royal Victoria Hospital’s Department of Cardiovascular Surgery.

He helped confirm a theory about the development of arteriosclerosis (hardening of the arteries) in the abdominal aorta, a major artery leading to the heart.

Vatistas and his team conducted a simulation of blood flow in the abdominal aorta, using the numerical models they developed. “The equations are the same; we just adjusted them for the geometry in the aorta,” he explained.

“We tested a theory which states that areas in arteries exposed to sheer stress are more prone to arteriosclerosis. Areas where arteries branch out undergo more stress, which can cause an injury. The scab then catches cholesterol. Medical studies had suggested that this was a risk factor, but we were able to confirm it.”

Part of Vatistas’s research is sponsored by NSERC.