Fluid Mechanics, Heat Transfer and Mass Transfer
In the context of fluid mechanics. the Bejan number is the dimensionless pressure drop along a channel of length :
where
- is the dynamic viscosity
- is the momentum diffusivity
In the context of heat transfer. the Bejan number is the dimensionless pressure drop along a channel of length :
where
- is the dynamic viscosity
- is the thermal diffusivity
The Be number plays in forced convection the same role that the Rayleigh number plays in natural convection.
In the context of mass transfer. the Bejan number is the dimensionless pressure drop along a channel of length :
where
- is the dynamic viscosity
- is the mass diffusivity
For the case of Reynolds analogy (Le = Pr = Sc = 1), it is clear that all three definitions of Bejan number are the same.
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