Lloyd MacGregor Trefethen (March 15, 1919 – November 6, 2001) was an American expert in

fluid dynamics In physics, physical chemistry and engineering, fluid dynamics is a subdiscipline of fluid mechanics that describes the flow of fluids – liquids and gases. It has several subdisciplines, including (the study of air and other gases in motion ...

known for his invention of the

heat pipe A heat pipe is a heat-transfer device that employs phase transition to transfer heat between two solid interfaces. At the hot interface of a heat pipe, a volatile liquid in contact with a thermally conductive solid surface turns into a vapor ...

and his research on the

Coriolis effect In physics, the Coriolis force is a pseudo force that acts on objects in motion within a frame of reference that rotates with respect to an inertial frame. In a reference frame with clockwise rotation, the force acts to the left of the moti ...

and card shuffling. He was for many years a professor of

mechanical engineering Mechanical engineering is the study of physical machines and mechanism (engineering), mechanisms that may involve force and movement. It is an engineering branch that combines engineering physics and engineering mathematics, mathematics principl ...

Tufts University Tufts University is a private research university in Medford and Somerville, Massachusetts, United States, with additional facilities in Boston and Grafton, as well as Talloires, France. Tufts also has several Doctor of Physical Therapy p ...

Early life and education

Trefethen was born on March 15, 1919, in

Waltham, Massachusetts Waltham ( ) is a city in Middlesex County, Massachusetts, United States, and was an early center for the labor movement as well as a major contributor to the Technological and industrial history of the United States, American Industrial Revoluti ...

. He graduated from the Webb Institute in 1940, and went to the

Massachusetts Institute of Technology The Massachusetts Institute of Technology (MIT) is a Private university, private research university in Cambridge, Massachusetts, United States. Established in 1861, MIT has played a significant role in the development of many areas of moder ...

for a master's degree in naval engineering. During World War II, poor eyesight made Trefethen ineligible for the Navy, so instead he signed up for the

United States Merchant Marine The United States Merchant Marine is an organization composed of United States civilian sailor, mariners and U.S. civilian and federally owned merchant vessels. Both the civilian mariners and the merchant vessels are managed by a combination of ...

. There he met Florence Newman, a Navy codebreaker who later became a professor of English at

. They married in 1944. Their son Lloyd N. Trefethen later became a notable mathematician; they also had an older daughter, quilter Gwyned Trefethen. In 1950, Trefethen completed a Ph.D. at the

University of Cambridge The University of Cambridge is a Public university, public collegiate university, collegiate research university in Cambridge, England. Founded in 1209, the University of Cambridge is the List of oldest universities in continuous operation, wo ...

. Although his initial plan of research was on cooling

turbine A turbine ( or ) (from the Greek , ''tyrbē'', or Latin ''turbo'', meaning vortex) is a rotary mechanical device that extracts energy from a fluid flow and converts it into useful work. The work produced can be used for generating electrical ...

blades, his eventual dissertation was ''Heat Transfer Properties of Liquid Metals'', and his work sparked an ongoing interest in

magnetohydrodynamics In physics and engineering, magnetohydrodynamics (MHD; also called magneto-fluid dynamics or hydromagnetics) is a model of electrically conducting fluids that treats all interpenetrating particle species together as a single Continuum ...

at Cambridge.

Career and later life

On returning to the US, Trefethen took a managerial position at the

National Science Foundation The U.S. National Science Foundation (NSF) is an Independent agencies of the United States government#Examples of independent agencies, independent agency of the Federal government of the United States, United States federal government that su ...

before joining

Harvard University Harvard University is a Private university, private Ivy League research university in Cambridge, Massachusetts, United States. Founded in 1636 and named for its first benefactor, the History of the Puritans in North America, Puritan clergyma ...

as an assistant professor of engineering in 1954. He moved to

in 1958, where he became a full professor and the chair of the mechanical engineering department. He retired in 1989. Trefethen died on November 6, 2001.

Contributions

Trefethen was known for his research on

surface tension Surface tension is the tendency of liquid surfaces at rest to shrink into the minimum surface area possible. Surface tension (physics), tension is what allows objects with a higher density than water such as razor blades and insects (e.g. Ge ...

in liquid droplets, and he became one of the independent inventors of the

. In 1963 he produced an award-winning educational film, ''Surface Tension in Fluid Mechanics'', for Encyclopædia Britannica Films. Trefethen's contributions to fluid mechanics also included widely reported experiments on the folklore claims that the

Coriolis force In physics, the Coriolis force is a pseudo force that acts on objects in motion within a frame of reference that rotates with respect to an inertial frame. In a reference frame with clockwise rotation, the force acts to the left of the motio ...

can cause the vortex in a drain to rotate in opposite directions in the northern and southern hemispheres. Beyond fluid dynamics, Trefethen's publications include a paper with his son Lloyd N. Trefethen on the Gilbert–Shannon–Reeds model, a mathematical model of

shuffling Shuffling is a technique used to randomize a deck of playing cards, introducing an element of chance into card games. Various shuffling methods exist, each with its own characteristics and potential for manipulation. One of the simplest shuf ...

playing cards. In contrast to earlier research suggesting that seven riffles are needed to remove any patterns from an unshuffled deck of cards, Trefethen and Trefethen showed that, in their model of the problem, five riffles are enough.

Recognition

Trefethen was a Fellow of the ASME. In 1999, a special issue of the ''Journal of Fluids Engineering'' was dedicated to Trefethen to honor his 80th birthday.

Selected publications

References

{{DEFAULTSORT:Trefethen, Lloyd M. 1919 births 2001 deaths People from Waltham, Massachusetts American mechanical engineers Webb Institute alumni MIT School of Engineering alumni Alumni of the University of Cambridge Harvard University faculty Tufts University faculty Fellows of the American Society of Mechanical Engineers Lloyd United States Merchant Mariners of World War II