Engines of Our Ingenuity

No. 2164:
HELE-SHAW

by John H. Lienhard

Today, a remarkable engineer from another century. The University of Houston's College of Engineering presents this series about the machines that make our civilization run, and the people whose ingenuity created them.

Years ago I studied fluid mechanics at Berkeley, and I learned about Hele-Shaw flows. You drive fluid past an obstacle mounted between two sheets of glass, a millimeter or so apart. Against all intuition, the flow behaves as though it had no viscosity. At the time, I imagined separate discoveries of this remarkable oddity by a European named Hele, and a Brit named Shaw. Now I find a 1909 book on automobile mechanics that displays a Hele-Shaw clutch. How very odd to find those names associated with both embryonic automobiles, and arcane fluid dynamics.

It turns out that Henry Selby Hele Shaw was only one person, not two. Born East of London in 1854, he apprenticed in an engineering firm at seventeen while he went to night school. When it came time for his national graduation exams he showed up deathly ill, and wrapped in blankets. Still, he came away with the top score.

Hele was his mother's maiden name. About the time he finished school, he hyphenated it to his surname, Shaw. During the next 28 years, Hele-Shaw worked as an academic, founding three new engineering schools, two in England and one in South Africa. Then he left academia to pursue his first love -- invention.

He'd begun inventing after the collapse of a new bridge over the River Tay. He was just out of school when gale winds tore the bridge apart killing 75 people and sending shock-waves across Great Britain. Hele-Shaw responded by inventing an integrating anemometer to give better data about wind loads on structures.

He did a lot with early calculation machinery -- planimeters and other mechanical integrators. But a fluid flow subtext flowed through his inventions. As he became interested in fluids flowing around objects, he developed a thin cell, with liquid flowing through it, that he could slip into a slide projector for his lectures.

That led to the Hele-Shaw flow idea, and to an early description of a boundary layer -- where moving fluid adheres to a body, causing drag. He even suggested reducing drag by altering that layer, they way the skin of a swimming shark or porpoise does.

So what about that Hele-Shaw clutch? Well, it seems he also took a very early interest in automobiles. He owned an original Benz car in an age when he was still required by law to have a man with red flag running ahead of him.

The connection of a car's motor to its drive was a huge early problem, and many clutches were invented. Hele-Shaw's was, for a season, the most widely used. Several disks with V-shaped groove rings floated in oil. To engage the engine, the disks were pressed together, quietly establishing a frictional connection.

So I come away from these revelations about Hele-Shaw wondering: Was he one more uncommon genius. Or was this an uncommon age -- one in which a single person could still do so many things.

I'm John Lienhard, at the University of Houston, where we're interested in the way inventive minds work.

(Theme music)


T. H. Russell, Automobile Motors and Mechanism. (Chicago: The Charles C. Thompson Co., 1909).

H. L. Guy, H. S. Hele-Shaw. 1854-1941. Obituary Notices of Fellows of the Royal Society, Vol. 3, No. 10, Dec., 1941, pp. 790-811.

H. Schlichting, Boundary-Layer Theory. (New York: McGraw-Hill, Inc., 1968/1955) pp. 114-116.


Hele-Shaw clutch

Hele-Shaw flow
A Hele-Shaw flow (Schlichting, pg. 116.). Here we see ink-marked streamlines of a flow that is very thin in the direction perpendicular to the page. The pattern is that of a frictionless or inviscid flow -- a so-called "potential flow" -- except at the furthermost point aft of the cylinder (on the right) where the representation breaks down.


The Engines of Our Ingenuity is Copyright © 1988-2006 by John H. Lienhard.