Bejan number
There are two different Bejan numbers (Be) named after Duke University professor Adrian Bejan which are used in the scientific domains of thermodynamics and fluid mechanics.
In the context of thermodynamics, the Bejan number is the ratio of heat transfer irreversibility to total irreversibility due to heat transfer and fluid friction:
where
In the context of fluid mechanics. the Bejan number is the dimensionless pressure drop along a channel of length :
where
In the context of heat transfer. the Bejan number is the dimensionless pressure drop along a channel of length :
where
The Be number plays in forced convection the same role that the Rayleigh number plays in natural convection.
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