In
fluid mechanics
Fluid mechanics is the branch of physics concerned with the mechanics of fluids (liquids, gases, and plasma (physics), plasmas) and the forces on them.
Originally applied to water (hydromechanics), it found applications in a wide range of discipl ...
, a homentropic flow has uniform and constant
entropy
Entropy is a scientific concept, most commonly associated with states of disorder, randomness, or uncertainty. The term and the concept are used in diverse fields, from classical thermodynamics, where it was first recognized, to the micros ...
. It distinguishes itself from an
isentropic or particle isentropic flow, where the entropy level of each fluid particle does not change with time, but may vary from particle to particle. This means that a homentropic flow is necessarily isentropic, but an isentropic flow need not be homentropic.
A homentropic and
perfect gas
In physics, engineering, and physical chemistry, a perfect gas is a theoretical gas model that differs from real gases in specific ways that makes certain calculations easier to handle. In all perfect gas models, intermolecular forces are neglecte ...
is an example of a
barotropic fluid
In fluid dynamics, a barotropic fluid is a fluid whose density is a function of pressure only. The barotropic fluid is a useful model of fluid behavior in a wide variety of scientific fields, from meteorology to astrophysics.
The density of most ...
where the pressure and density are related by
where
is a constant.
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