Jean Léonard Marie Poiseuille (; 22 April 1797
– 26 December 1869) was a French
physicist
A physicist is a scientist who specializes in the field of physics, which encompasses the interactions of matter and energy at all length and time scales in the physical universe.
Physicists generally are interested in the root or ultimate cau ...
and
physiologist.
Poiseuille was born in
Paris
Paris () is the Capital city, capital and List of communes in France with over 20,000 inhabitants, most populous city of France, with an estimated population of 2,165,423 residents in 2019 in an area of more than 105 km² (41 sq mi), ma ...
,
France
France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of overseas regions and territories in the Americas and the Atlantic, Pacific and Indian Oceans. Its metropolitan area ...
, and he died there on 26 December 1869.
Fluid flow
From 1815 to 1816 he studied at the
École Polytechnique
École may refer to:
* an elementary school in the French educational stages normally followed by secondary education establishments (collège and lycée)
* École (river), a tributary of the Seine flowing in région Île-de-France
* École, Savoi ...
in Paris. He was trained in
physics
Physics is the natural science that studies matter, its fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. "Physical science is that department of knowledge which r ...
and
mathematics. In 1828 he earned his
D.Sc. degree with a dissertation entitled ''Recherches sur la force du coeur aortique''. He was interested in the flow of
human
Humans (''Homo sapiens'') are the most abundant and widespread species of primate, characterized by bipedalism and exceptional cognitive skills due to a large and complex brain. This has enabled the development of advanced tools, cultu ...
blood
Blood is a body fluid in the circulatory system of humans and other vertebrates that delivers necessary substances such as nutrients and oxygen to the cells, and transports metabolic waste products away from those same cells. Blood in the cir ...
in narrow tubes.
In 1838 he experimentally derived, and in 1840 and 1846 formulated and published, Poiseuille's law (now commonly known as the
Hagen–Poiseuille equation, crediting
Gotthilf Hagen
Gotthilf Heinrich Ludwig Hagen (3 March 1797 – 3 February 1884) was a German civil engineer who made important contributions to fluid dynamics, hydraulic engineering and probability theory.
Life and work
Hagen was born in Königsberg, East Prus ...
as well), which applies to
laminar flow, that is, non-turbulent flow of liquids through pipes of uniform section, such as blood flow in
capillaries
A capillary is a small blood vessel from 5 to 10 micrometres (μm) in diameter. Capillaries are composed of only the tunica intima, consisting of a thin wall of simple squamous endothelial cells. They are the smallest blood vessels in the body: ...
and
veins. His original formulation for water of 1846
little resembles the present-day formulation and is given as:
:
However it can be transformed in a more amenable form. Rewritting in more modern fashion using SI units gives:
:
Using the density of water as
and
and then solving for the pressure difference results in:
:
The term in parentheses, the constant and the temperature correction, are a function of viscosity. Finally using the viscosity of water at
,
, allows for viscosity of different fluids to be taken into account resulting in:
:
The equation in standard fluid dynamics notation is
:
or
:
or
:
where:
:
is the pressure loss,
:
is the length of pipe,
:
is the
dynamic viscosity,
:
is the
volumetric flow rate,
:
is the
radius
In classical geometry, a radius ( : radii) of a circle or sphere is any of the line segments from its center to its perimeter, and in more modern usage, it is also their length. The name comes from the latin ''radius'', meaning ray but also the ...
,
:
is the
diameter
In geometry, a diameter of a circle is any straight line segment that passes through the center of the circle and whose endpoints lie on the circle. It can also be defined as the longest chord of the circle. Both definitions are also valid fo ...
,
:
is the mathematical constant
π,
:
is the average
velocity
Velocity is the directional speed of an object in motion as an indication of its rate of change in position as observed from a particular frame of reference and as measured by a particular standard of time (e.g. northbound). Velocity i ...
.
The
poise, the unit of
viscosity
The viscosity of a fluid is a measure of its resistance to deformation at a given rate. For liquids, it corresponds to the informal concept of "thickness": for example, syrup has a higher viscosity than water.
Viscosity quantifies the inte ...
in the
CGS system, was named after him. Attempts to introduce "
poiseuille" as the name of the
SI unit
Pa·
s were unsuccessful.
Notes
References
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External links
*
{{DEFAULTSORT:Poiseuille, Jean Leonard Marie
1799 births
1869 deaths
19th-century French physicians
Fluid dynamicists
French physiologists