Eckert number
Encyclopedia
The Eckert number is a dimentionless number used in fluid dynamics
. It expresses the relationship between a flow's kinetic energy
and enthalpy
, and is used to characterize dissipation
. It is named after Ernst R. G. Eckert
.
It is defined as
where
Fluid dynamics
In physics, fluid dynamics is a sub-discipline of fluid mechanics that deals with fluid flow—the natural science of fluids in motion. It has several subdisciplines itself, including aerodynamics and hydrodynamics...
. It expresses the relationship between a flow's kinetic energy
Kinetic energy
The kinetic energy of an object is the energy which it possesses due to its motion.It is defined as the work needed to accelerate a body of a given mass from rest to its stated velocity. Having gained this energy during its acceleration, the body maintains this kinetic energy unless its speed changes...
and enthalpy
Enthalpy
Enthalpy is a measure of the total energy of a thermodynamic system. It includes the internal energy, which is the energy required to create a system, and the amount of energy required to make room for it by displacing its environment and establishing its volume and pressure.Enthalpy is a...
, and is used to characterize dissipation
Dissipation
In physics, dissipation embodies the concept of a dynamical system where important mechanical models, such as waves or oscillations, lose energy over time, typically from friction or turbulence. The lost energy converts into heat, which raises the temperature of the system. Such systems are called...
. It is named after Ernst R. G. Eckert
Ernst R. G. Eckert
Dr Ernst R. G. Eckert was a scientist who advanced the film cooling technique for aeronautical engines. Eckert worked as a rocket and jet engine scientist at the Aeronautical Research Institute in Braunschweig, Germany, then via Operation Paperclip, began jet propulsion research in 1945 at...
.
It is defined as
where
-
is a characteristic velocity of the flow. -
is the constant-pressure specific heat of the flow. -
is a characteristic temperature difference of the flow.